CDMA. Fundamentals of Wireless Communications & CDMA. Student Guide CDMA X6 January 24, 2000

Transcription

1 Fundamentals of Wireless Communications & CDMA Student Guide CDMA-050 January 24, 2000

2 Material Use Restrictions These written materials are to be used only in conjunction with the associated instructor-led class. They are not intended to be used solely as reference material. No part of these written materials may be used or reproduced in any manner whatsoever without the written permission of QUALCOMM Incorporated. Copyright 2000 QUALCOMM Incorporated. All rights reserved. Printed in the United States of America. QUALCOMM Incorporated 5775 Morehouse Drive San Diego, CA U.S.A.

3 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Background Section 1 Background QUALCOMM Proprietary 1-1

4 Background CDMA-050 Fundamentals of Wireless Communicaions & CDMA Section Introduction Communications History Cellular Telephony Industry Overview Analog & Digital Communications Figure 1-1 Section Introduction 1-2 QUALCOMM Proprietary

5 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Background Section Introduction In this section the following topics will be discussed: Communications History Cellular Telephony Industry Overview Analog & Digital Communications QUALCOMM Proprietary 1-3

6 Background CDMA-050 Fundamentals of Wireless Communicaions & CDMA Section Objectives Describe communication systems. List major milestones in the history of telecommunications. Describe the FCC standard for cellular and PCS spectrum. Describe analog and digital communications. Figure 1-2 Section Objectives 1-4 QUALCOMM Proprietary

7 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Background Section Objectives The objectives of the this section are to: Describe the parts of a communication system. List the major milestones in the history of telecommunications. Describe the FCC standard for the cellular and PCS spectrum. Describe analog and digital communications. QUALCOMM Proprietary 1-5

8 Background CDMA-050 Fundamentals of Wireless Communicaions & CDMA Communication Systems Deliver as much information as possible from the source to the destination (capacity issues). Deliver information in shortest time (delay issues). Reduce errors in delivery of information (error detection/correction issues). Figure 1-3 Purpose of a Communication System Yagi, Uda Figure 1-4 Voice Communications 1-6 QUALCOMM Proprietary

9 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Background Communication Systems Voice communications is the simplest mode of communications. People also use facial expressions and body language to communicate with each other. Purpose of a Communication System Deliver as much information as possible from the source to the destination (capacity issues). Information maybe of different natures, such as voice, video, or data produced by a computer. Deliver information in shortest time (delay issues). Reduce errors in delivery of information (error detection/correction issues). Basic Communications System Elements Transmitter Receiver Medium: terrestrial (e.g. cable, coax, wire, etc.), and x-terrestrial (e.g. radio transmission) QUALCOMM Proprietary 1-7

10 Background CDMA-050 Fundamentals of Wireless Communicaions & CDMA Long Distance Communications Figure 1-5 Telecommunications 1-8 QUALCOMM Proprietary

11 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Background Long Distance Communications Tele is greek for at a distance or far off, and Communicare is latin for to make common. Telecommunication is the process of long distance communications. Early telecommunications involved smoke, flags, drums, and other such methods to relay messages and information. QUALCOMM Proprietary 1-9

12 Background CDMA-050 Fundamentals of Wireless Communicaions & CDMA Telegraph Figure 1-6 Morse Code 1-10 QUALCOMM Proprietary

13 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Background Telegraph The first wireline communications was the telegraph. Invented in the mid 19th century, it opened a new era in long-distance telecommunication. The letters in the alphabet were encoded into patterns of short or long pulses. This technique is known as Morse Code. The electric pulses were transmitted over telegraph lines. This type of communication required the two parties to know the code. It also needed an actual physical connection between the transmitter and the receiver by wire (cables). Lack of any two elements would have made the communication impossible. QUALCOMM Proprietary 1-11

14 Background CDMA-050 Fundamentals of Wireless Communicaions & CDMA Telephone Figure 1-7 Invention of the Telephone 1-12 QUALCOMM Proprietary

15 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Background Telephone When we talk over the telephone, our voice is converted to a electronic signal by the microphone in the handset. This signal is then transmitted over telephone wires. A telephone is a device that is capable of transmitting and receiving at the same time. Devices that can transmit and receive at the same time are called full duplex devices. QUALCOMM Proprietary 1-13

16 Background CDMA-050 Fundamentals of Wireless Communicaions & CDMA Telephone Networks PSTN Figure 1-8 Switching and Telephone Networks 1-14 QUALCOMM Proprietary

17 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Background Telephone Networks Early Switching Devices Switches are devices that cause a connection between two transmitting/receiving devices. The earliest switching devices were manually operated patch panels. In the late 19th century the electronic switch was developed. Modern Switching Devices Today many different types of automated switches are used which make it possible for fast placement of calls. A system, using DSS7 switching for instance, can make a connection between any two landline phones, in the country, in about 1 second. QUALCOMM Proprietary 1-15

18 Background CDMA-050 Fundamentals of Wireless Communicaions & CDMA Wireless Telecommunications Figure 1-9 First Wireless Telecommunications 1-16 QUALCOMM Proprietary

19 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Background Wireless Telecommunications With the invention of the radio, expensive cabling requirements were eliminated and transoceanic wireless communication became possible. Radio was invented by Marconi an Italian scientist in In radio communication the information signal is converted into an electromagnetic wave form and is broadcast in space using radiating devices known as antennas. QUALCOMM Proprietary 1-17

20 Background CDMA-050 Fundamentals of Wireless Communicaions & CDMA Terminology Kilo (K) = 1,000 Mega (M) = 1,000,000 Giga (G) = 1,000,000,000 milli (m) = micro (µ) = nano (n) = Figure 1-10 Terminology 1-18 QUALCOMM Proprietary

21 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Background Terminology Kilo (K) means 1,000 and is equal to 1x10 3. Mega (M) means1,000,000 and is equal to 1x10 6 Giga (G) means 1,000,000,000 and is equal to 1x10 9. milli (m) means and is equal to 1x10-3. micro (µ) means and is equal to 1x10-6. nano (n) means and is equal to 1x10-9. QUALCOMM Proprietary 1-19

22 Background CDMA-050 Fundamentals of Wireless Communicaions & CDMA Analog and Digital Signals Figure 1-11 Analog Signals C D M A Figure 1-12 Digital Signals 1-20 QUALCOMM Proprietary

23 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Background Analog and Digital Signals Analog Signals Analog signals, such as voice, have frequency and amplitude components. These two components define the characteristics of the signal A woman s voices is much higher in frequency than a man s. Amplitude is how loud a person talks. A analog communication system employs a continuous transmission that varies in frequency and amplitude. Digital Signals A digital signal is a series discrete values. In binary digital systems there are only two distinct values which generally are represented by 0 and 1. Each 0 or 1 is designated as a bit or digit. A digital communication system can use discontinuous transmission that may vary in frequency, amplitude, phase, or polarity. QUALCOMM Proprietary 1-21

24 Background CDMA-050 Fundamentals of Wireless Communicaions & CDMA Digital and Telecommunications Figure 1-13 Data Communications 1-22 QUALCOMM Proprietary

25 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Background Digital and Telecommunications With the development of digital technology signals could be digitized and processed very fast, using fast digital machines such as micro-processor (computers). The marriage of computers and computer controlled devices paved the way for digital technology. This new capability provides higher-quality and more reliable methods for audio, video and data transmission. QUALCOMM Proprietary 1-23

26 Background CDMA-050 Fundamentals of Wireless Communicaions & CDMA Mobile Telephones PSTN Figure 1-14 First Mobile Telephones 1-24 QUALCOMM Proprietary

27 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Background Mobile Telephones Mobile Telephones Unlike the traditional telephone, which requires wire connections between telephones, the mobile telephone broadcasts its signals through the air. The first wireless telephone system used a single transmission which covered a large area. Very powerful transmitters and very high antenna towers were required to cover a large area. Advantages of Mobile Telephone Not restricted by the location of a telephone wall jack. New market opportunities. Disadvantages of Mobile Telephone Phones and air time was expensive. Phones were big and bulky. Limited coverage, when the edge of the cell was reached you either stopped or dropped the call. Limited capacity, limited number of frequencies were available for use. No privacy. QUALCOMM Proprietary 1-25

28 Background CDMA-050 Fundamentals of Wireless Communicaions & CDMA Cellular Telephones Figure 1-15 Analog Cellular Telephones 1-26 QUALCOMM Proprietary

29 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Background Cellular Telephones New Wireless Service Federal Communications Commission (FCC) provided new and more frequencies for wireless services. Tests for cellular networks were conducted in Chicago in the early 1980 s. Commercial services started shortly after the testing. New methods of control were developed which allowed for better services. This paved the way for expanded services, more service providers, and greater mobility. Advantages Truly mobile communications - calls could be carried from one cell site to another. Full duplex operation. Greater capacity. Greater coverage. Greater service area. More service areas available. Disadvantages No privacy. QUALCOMM Proprietary 1-27

30 Background CDMA-050 Fundamentals of Wireless Communicaions & CDMA Cellular Network PSTN MTSO Forward Reverse Figure 1-16 Cellular Network Components 1-28 QUALCOMM Proprietary

31 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Background Cellular Network Cellular Service The service providers used a network of cells in a geographical area to provide service. This reduced the requirement for a high-powered transceiver and accommodated more users. With the advancement of newer technology, service, and reduced service cost the system and network capacity was quickly reached and new demands were placed on service providers. Network Components Cell site - transmitter and receiver for phone connection. Mobile telephone switching office (MTSO) - control and operational purposes. Public switched telephone network (PSTN) - connection to phones located in individual homes. QUALCOMM Proprietary 1-29

32 Background CDMA-050 Fundamentals of Wireless Communicaions & CDMA Coverage in a Market City MTSO PSTN Small Town Figure 1-17 Markets and Network Coverage 1-30 QUALCOMM Proprietary

33 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Background Coverage in a Market Cellular Markets Markets are a geographical area designated by the FCC where a service provider could deploy a network and provide service. One or more networks would be deployed, by a service provider, to provide adequate coverage and capacity in a market. QUALCOMM Proprietary 1-31

34 Background CDMA-050 Fundamentals of Wireless Communicaions & CDMA Cellular Carriers and Markets Frequency Band Carriers / Market No. of Channels Channel Width Rev / Fwd Link Separation 800 MHz A = 12.5 MHz B = 12.5 MHz A = 416 B = KHz 45 MHz Table 1-1 Cellular Spectrum A A B A B 1 MHz MHz 10 MHz 1.5 MHz MHz Figure 1-18 Cellular Carriers 1-32 QUALCOMM Proprietary

35 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Background Cellular Carriers and Markets Cellular Spectrum There is 50 MHz of band allocated for cellular operation in the 800 MHz band. There is 25 MHz used for reverse link transmission and the remaining 25 MHz is used for forward link transmission. Each link is divided into 832 channels. The separation between each channel is 30 KHz. The channels are used in pairs so for any given reverse link channel there will be a corresponding forward link channel. Cellular Carriers The FCC allocated 2 different service providers in a market. Each carrier is allocated 12.5 MHz on the reverse link and 12.5 MHz on the forward link. A market is called a cellular geographical service area (CGSA). Non-wireline service providers were designate as A carriers. The A carriers were companies that had no affiliation with companies providing phone service to homes in the market. Wireline service providers were designated B carriers. The companies were affiliated with companies providing phone service to homes in the market. QUALCOMM Proprietary 1-33

36 Background CDMA-050 Fundamentals of Wireless Communicaions & CDMA PCS Carriers and Markets Frequency Band Carriers / Market No. of Channels Channel Width Rev / Fwd Link Separation 1900 MHz A, B, & C = 15 MHz ea. D, E, & F = 5 MHz ea. A, B, & C = 300 ea D, E, & F = 100 ea 50 KHz 80 MHz Table 1-2 PCS Spectrum A D B E F C 15 MHz 5 MHz 15 MHz 5 MHz 5 MHz 15 MHz Figure 1-19 PCS Carriers 1-34 QUALCOMM Proprietary

37 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Background PCS Carriers and Markets In 1995 the FCC allocated and auctioned new frequency spectrum to service providers to use in deploying new wireless communications networks. The new spectrum was for use of personal communication services or PCS. The PCS spectrum is structured for digital wireless communications. PCS Spectrum There is 120 MHz of band allocated for PCS operation in the 1900 MHz band. There is 60 MHz used for reverse link transmission and the remaining 60 MHz is used for forward link transmission. The PCS spectrum is divided into 1200 frequencies designated as channels. The separation between each channel is 50 KHz. The channels are used in pairs so for any given reverse link channel there will be a corresponding forward link channel. PCS Carriers The FCC allocated 6 service providers in a market. Markets maybe called a major trading area (MTA) or a basic trading area (BTA). The A, B, and C carriers are each allocated 15 MHz of spectrum on the reverse link and 15 MHz on the forward link. The D, E, and F carriers are each allocated 5 MHz of spectrum on the reverse link and 5 MHz on the forward link. QUALCOMM Proprietary 1-35

38 Background CDMA-050 Fundamentals of Wireless Communicaions & CDMA Analog Speech Signals about 200 milliseconds Figure 1-20 Voice signal 1-36 QUALCOMM Proprietary

39 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Background Analog Speech Signals Voice is an analog signal. Analysis show that in an average two way conversation, a person is talking about 40% of the time. The remainder of the conversation is made of pauses in a speech and the time spent on listening to the other party. Most human speech is contained between 300 to 3.3 KHz while the human ear can hear frequencies up to 20 KHz. QUALCOMM Proprietary 1-37

40 Background CDMA-050 Fundamentals of Wireless Communicaions & CDMA Analog to Digital Conversion level T1 T2 T3 T4 T5 T6 time Time Interval: T1 T2 T3 T4 T5 T6 Digital Values: Figure 1-21 A/D Conversion 1-38 QUALCOMM Proprietary

41 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Background Analog to Digital Conversion Analog to Digital Conversion (A/D) Sampling - The amplitude of a voice signal is measured at regular time intervals. Quantization - A digital value is given to each discrete amplitudes level. Accuracy is dependent on the number of discrete levels and the number of samples. Pulse Code Modulation (PCM) PCM is the most common method used to convert a voice signal into a digital signal. This process is used by telephone service providers throughout the world. QUALCOMM Proprietary 1-39

42 Background CDMA-050 Fundamentals of Wireless Communicaions & CDMA Digital to Analog Conversion level Actual Waveform Reproduced Waveform T1 T2 T3 T4 T5 T6 time Time Interval: T1 T2 T3 T4 T5 T6 Digital Values: Figure 1-22 D/A Conversion 1-40 QUALCOMM Proprietary

43 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Background Digital to Analog Conversion Digital to Analog Conversion (D/A) The original analog signal can be reconstructed using the digital samples. The quality of the sound is dependent on the A/D conversion device used. QUALCOMM Proprietary 1-41

44 Background CDMA-050 Fundamentals of Wireless Communicaions & CDMA Transmission of Digital Signals Figure 1-23 Data Over the Air 1-42 QUALCOMM Proprietary

45 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Background Transmission of Digital Signals Digital information is not transmitted over the air. It must be converted to a signal that will carry the digital information. Radio Frequency signals (RF) are used to send the digital information. An RF signal may carry the information in either the phase or the frequency. Phase The digital information can be used to change the phase of the RF signal. A digital 1 is represented by one phase while a digital 0 is represented by another phase. Frequency The digital information can be used to change the frequency of the RF signal. A digital 1 is represented by one frequency while a digital 0 is represented by another frequency. QUALCOMM Proprietary 1-43

46 Background CDMA-050 Fundamentals of Wireless Communicaions & CDMA Advantages of Digital Noise Reduction Digital Signal Processing (DSP) Coding Capability Ease of Implementation Digital Duck Analog Artifact Figure 1-24 Digital Advantages 1-44 QUALCOMM Proprietary

47 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Background Advantages of Digital Noise Reduction Digital signals are more immune to noise than analog signals. DSP Techniques Digital signal processing (DSP) can be used to increase the speed of the information that is sent. The signal can be conditioned so the information can be less distorted during transmission. Coding Capability Signals can be encrypted for more privacy. Errors in a transmission can be detected and/or corrected. Ease of Implementation Digital components are smaller than analog devices. Digital devices are cheaper and easily designed. Digital signals can be easily stored and recovered upon demand. QUALCOMM Proprietary 1-45

48 Background CDMA-050 Fundamentals of Wireless Communicaions & CDMA Section Summary Communications History Cellular Telephony Industry Overview Analog & Digital Communications Figure 1-25 Section Summary 1-46 QUALCOMM Proprietary

49 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Background Section Summary Describe the parts of a communication system. List the major milestones in telecommunications history. Describe the FCC standard for the cellular and PCS spectrum. Describe analog and digital communications. QUALCOMM Proprietary 1-47

50 Background CDMA-050 Fundamentals of Wireless Communicaions & CDMA Comments/Notes 1-48 QUALCOMM Proprietary

51 Fundamentals of Wireless Communicaions & CDMA CDMA-050 The Cellular System Section 2 The Cellular System QUALCOMM Proprietary 2-1

52 The Cellular System CDMA-050 Fundamentals of Wireless Communicaions & CDMA Section Introduction Cellular Architecture CDMA Equipment Types of Calls Figure 2-1 Section Introduction 2-2 QUALCOMM Proprietary

53 Fundamentals of Wireless Communicaions & CDMA CDMA-050 The Cellular System Section Introduction In this section the following topics will be discussed: Cellular Architecture CDMA Equipment Types of Calls QUALCOMM Proprietary 2-3

54 The Cellular System CDMA-050 Fundamentals of Wireless Communicaions & CDMA Section Objectives List the components of a cellular network. List the CDMA infrasturcture hardware. Describe the types of calls in a cellular system. Figure 2-2 Section Objectives 2-4 QUALCOMM Proprietary

55 Fundamentals of Wireless Communicaions & CDMA CDMA-050 The Cellular System Section Objectives The objectives of the this section are to: List the components of a cellular network. List the CDMA infrastructure hardware. Describe the types of calls in a cellular system. QUALCOMM Proprietary 2-5

56 The Cellular System CDMA-050 Fundamentals of Wireless Communicaions & CDMA Network Components BTS PSTN BTS BSC BTS Figure 2-3 Basic Digital Architecture 2-6 QUALCOMM Proprietary

57 Fundamentals of Wireless Communicaions & CDMA CDMA-050 The Cellular System Network Components A digital wireless system has 4 basic components: Mobile phones (personal station (PS), mobile station (MS), portable, subscriber, user terminal (UT), handheld, or mobile) Base Station Transceiver Subsystem (BTS), Base Station (BS), or cell site. Base Station Controller (BSC), Mobile Switching Center (MSC), Mobile Telephone Switching Office (MTSO), or switch. Public switched telephone network (PSTN). QUALCOMM Proprietary 2-7

58 The Cellular System CDMA-050 Fundamentals of Wireless Communicaions & CDMA Network Interconnects BSC Alpha Sector PSTN Gamma Sector BTS Beta Sector Reverse Link Forward Link Figure 2-4 Network Interconnects 2-8 QUALCOMM Proprietary

59 Fundamentals of Wireless Communicaions & CDMA CDMA-050 The Cellular System Cellular Network Interconnects There are 3 types of connections for connecting the network components: Mobile to BTS: air links (forward & reverse links) BTS to BSC: backhaul (T1/E1) BSC to PSTN: POTS (plain old telephone service) (T1/E1) QUALCOMM Proprietary 2-9

60 The Cellular System CDMA-050 Fundamentals of Wireless Communicaions & CDMA Infrastructure Equipment BSC Indoor BTS Outdoor BTS Typical Rack Digital Rack RF Rack Figure 2-5 QUALCOMM Infrastructure 2-10 QUALCOMM Proprietary

61 Fundamentals of Wireless Communicaions & CDMA CDMA-050 The Cellular System Infrastructure Equipment Base Station Controller (BSC) BSC functions: Call control processes. Database of subscribers. Record calls for billing. Switch the calls to the PSTN. Vocoding of the voice signal. Base Station Transceiver System BTS functions are: CDMA processing of all signals. Transmitting and receiving of all RF signals. There are 2 types of BTS one for indoor installation and the other for outdoor installation. BTS Sectorization A BTS may have up to 9 sectors. Each sector operates like an independent BTS but only additional hardware is required. In CDMA the addition of sectors in a BTS further increases the capacity. QUALCOMM Proprietary 2-11

62 The Cellular System CDMA-050 Fundamentals of Wireless Communicaions & CDMA Subscriber Units QCT-1000/1200 QCP-800/1900 Q Phone Figure 2-6 QUALCOMM Subscriber 2-12 QUALCOMM Proprietary

63 Fundamentals of Wireless Communicaions & CDMA CDMA-050 The Cellular System Subscriber Units Names For A Phone A wireless phone may have many names such as personal station (PS), mobile station (MS), portable, subscriber, user terminal (UT), handheld, or mobile. Cellular or PCS Applications Home (wireless local loop) Office (wireless private branch exchange (WPBX)) Portable QUALCOMM Proprietary 2-13

64 The Cellular System CDMA-050 Fundamentals of Wireless Communicaions & CDMA Types of Calls PSTN BSC #1 BSC #2 Figure 2-7 Call Types 2-14 QUALCOMM Proprietary

65 Fundamentals of Wireless Communicaions & CDMA CDMA-050 The Cellular System Types of Calls Defined by point of origin and point of destination. Mobile-to-Land (MTL) Mobile phone -> BTS -> BSC -> PSTN -> land line phone. Land-to-Mobile (LTM) Land line phone -> PSTN -> BSC -> BTS -> mobile phone. Mobile-to-Mobile (MTM) Mobile phone -> BTS -> BSC -> BTS -> mobile phone. This is for a call to an individual in the same network. Mobile phone -> BTS -> BSC #1 -> PSTN -> BSC #2 -> BTS -> mobile phone. This is for a call to an individual in a separate network with the same service provider or a different service provider. Who pays? Currently the owner of a wireless phone will always pay for air time. Long distance charges apply only when the call is placed from a wireless phone. QUALCOMM Proprietary 2-15

66 The Cellular System CDMA-050 Fundamentals of Wireless Communicaions & CDMA Section Summary Cellular Architecture CDMA Equipment Types of Calls Figure 2-8 Section Summary 2-16 QUALCOMM Proprietary

67 Fundamentals of Wireless Communicaions & CDMA CDMA-050 The Cellular System Section Summary List the components of a cellular network. List the CDMA infrastructure hardware. Describe the types of calls in a cellular system. QUALCOMM Proprietary 2-17

68 The Cellular System CDMA-050 Fundamentals of Wireless Communicaions & CDMA Comments/Notes 2-18 QUALCOMM Proprietary

69 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Multiple Access Systems Section 3 Multiple Access Systems QUALCOMM Proprietary 3-1

70 Multiple Access Systems CDMA-050 Fundamentals of Wireless Communicaions & CDMA Section Introduction Multiple Access Systems CDMA Channel Generation CDMA Channels Figure 3-1 Section Introduction 3-2 QUALCOMM Proprietary

71 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Multiple Access Systems Section Introduction In this section the following topics will be discussed: Multiple Access Systems CDMA Channel Generation CDMA Channels QUALCOMM Proprietary 3-3

72 Multiple Access Systems CDMA-050 Fundamentals of Wireless Communicaions & CDMA Section Objectives List the techniques used in multiple access systems. Describe the 5 steps to generate a CDMA signal. List the pourpose for each channel in a CDMA system. Figure 3-2 Section Objectives 3-4 QUALCOMM Proprietary

73 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Multiple Access Systems Section Objectives The objectives of the this section are to: List the techniques used in multiple access systems. Describe the 5 steps to generate a CDMA signal. List the purpose for each channel in a CDMA system. QUALCOMM Proprietary 3-5

74 Multiple Access Systems CDMA-050 Fundamentals of Wireless Communicaions & CDMA Wireless Interference Figure 3-3 Interference to a Mobile 3-6 QUALCOMM Proprietary

75 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Multiple Access Systems Wireless Interference Wireless communication systems use E&M waves to transmit signals through the air. When subscribers share the same frequency they will create interference. The amount of interference depends on what technic is used to reduce the interference. The resource: frequency The problem: interference The solutions: multiple access techniques QUALCOMM Proprietary 3-7

76 Multiple Access Systems CDMA-050 Fundamentals of Wireless Communicaions & CDMA Frequency Division Multiple Access Figure 3-4 FDMA (Analog) Cocktail Party HI I H HI GO Frequency Channel 1 O G GO Frequency Channel 2 Figure 3-5 How It Works 3-8 QUALCOMM Proprietary

77 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Multiple Access Systems Frequency Division Multiple Access Frequency Division Each Frequency Division Multiple Access (FDMA) subscriber is using the same medium (air) for communicating, but they are assigned a specific frequency channel. While they are using the frequency channel, no one else in that cell or neighboring cell can use the frequency channel. FDMA Cocktail Party (analogy) Two users have continuous access to the room. But, no one else can use the room while they are in it. QUALCOMM Proprietary 3-9

78 Multiple Access Systems CDMA-050 Fundamentals of Wireless Communicaions & CDMA Time Division Multiple Access Figure 3-6 TDMA Cocktail Party HI HI user 2 user 1 user 2 user 1 I O H G GO GO Figure 3-7 How it Works 3-10 QUALCOMM Proprietary

79 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Multiple Access Systems Time Division Multiple Access Time Division Time Division Multiple Access (TDMA) subscribers share a common frequency channel, but use the channel only for a short time. They are each given a time slot and allowed to transmit during that time slot only. When all of the available time slots in a given frequency are used the next user must be assigned to a time slot on another frequency. TDMA Cocktail Party (analogy) Subscribers have access to the same room, but only a pair of them can use the room for a short time. Then they must leave and another couple enters. Throughout the evening, the subscribers rotate usage of the room. QUALCOMM Proprietary 3-11

80 Multiple Access Systems CDMA-050 Fundamentals of Wireless Communicaions & CDMA Code Division Multiple Access (CDMA) Hello Bonjour Buenos Dias Guten Tag Shalom MMT Ac.eps Figure 3-8 CDMA Cocktail Party HI HI red code G O H I red code GO GO green code green code Figure 3-9 How it works 3-12 QUALCOMM Proprietary

81 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Multiple Access Systems Code Division Multiple Access Code Division Code Division Multiple Access subscribers share a common channel (frequency). All users are on the same frequency at the same time, they are divided however by codes. CDMA Cocktail Party (analogy) All subscribers are in the same room together. They can be all talking at the same time. They can be grouped together or standing across the room from each other. Unlike the other two multiple access systems, they do not have to leave the room! QUALCOMM Proprietary 3-13

82 Multiple Access Systems CDMA-050 Fundamentals of Wireless Communicaions & CDMA Technology Overview Channel Bandwidth Cellular Band Users / Sector / Channel Standard Channel Bandwidth Table 3-1 Wireless Technologies PCS Band Users / Sector / Channel Standard CDMA 1.25 MHz 22 / 14 IS-95A 1.25 MHz 22 / 14 ANSI J-STD-008 FDMA 30 KHz 1 IS-41 N/A N/A N/A (Analog) TDMA 30 KHz 3 IS KHz 3 IS-136 N. American 200 KHz 8 GSM 3-14 QUALCOMM Proprietary

83 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Multiple Access Systems Technology Overview The technique used to separate users in a channel will determine the channel capacity. Technologies FDMA (AMPS, DAMPS) TDMA (IS-54, IS-136, GSM) CDMA (IS-95, ANSI J-STD-008) Bands Not all technologies are used in the cellular band in the USA. This is due to the structure of the channel and requirements established by the FCC. QUALCOMM Proprietary 3-15

84 Multiple Access Systems CDMA-050 Fundamentals of Wireless Communicaions & CDMA CDMA System Block Diagram Antenna Voice A/D Converter Vocoder Encoder & Interleaver Spreader D/A RF Code Generator Figure 3-10 CDMA Block Diagram 3-16 QUALCOMM Proprietary

85 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Multiple Access Systems CDMA System Block Diagram Steps in Generating a CDMA Signal 1. Voice is digitized (PSTN). 2. Digitized voice is vocoded (BSC). 3. Digital signal is encoded and interleaver (BTS). 4. Encoded signals are spread (channelized) (BTS). 5. The digital signal converted and transmitted as a radio signal (BTS). QUALCOMM Proprietary 3-17

86 Multiple Access Systems CDMA-050 Fundamentals of Wireless Communicaions & CDMA Vocoder (Voice Compression) about 200 milliseconds Figure 3-11 Speech Activity A/D Pulse Coded Modulation (PCM) Vocoded Voice VOCODER Figure 3-12 Vocoder Operation 3-18 QUALCOMM Proprietary

87 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Multiple Access Systems Vocoder (Voice Compression) When we talk, we pause between syllables and words. CDMA takes advantage of these pauses in speech activity. Analog to digital conversion The voice signal is converted to a digital signal using PCM. Variable rate vocoder The vocoder (Voice Coder) is used to compress the digital signal from the Codec (Code/Decode). The vocoder, used in a CDMA system, compresses the voice signal into various data rates. The data rate is dynamically determined by the users speech activity. The vocoders are located at the BSC and in the phone. Vocoder rates The voice is compressed in the vocoder into either one of four rates (Full, 1/2, 1/4, or 1/8 rate). CDMA systems can use either an 8 kbps or 13 kbps vocoder. QUALCOMM Proprietary 3-19

88 Multiple Access Systems CDMA-050 Fundamentals of Wireless Communicaions & CDMA Encoding / Interleaving A B C D Bit Pattern A A A B B B C C C D D D Encoded Symbols A A A B???? C D D D Burst Errors A?? D Decoded Bits Figure 3-13 Encoding Example 3-20 QUALCOMM Proprietary

89 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Multiple Access Systems Encoding / Interleaving Purpose: The purpose of the encoder is to build redundancy into the signal. Example: A simple coding scheme is shown in this example. The digital message consists of four bits (A,B,C,D) of vocoded data. Each of the bits is repeated (encoded) 3 times. These encoded bits are called symbols. The encoder is located at the BTS and in the phone. Decoding: Decoding at the receiver uses a majority logic rule (two out of three wins). If an error occurs the redundancy can help recover the lost information. QUALCOMM Proprietary 3-21

90 Multiple Access Systems CDMA-050 Fundamentals of Wireless Communicaions & CDMA Encoding / Interleaving A B C D A A A B B B C C C D D D A B C D A B C D A B C D Bit Pattern Encoded Symbols Interleaved symbols A B C D???? A B C D Burst Errors A? A B? B C? C D? D De-interleaves Symbols A B C D Decoded Bits Figure 3-14 Interleaving Example 3-22 QUALCOMM Proprietary

91 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Multiple Access Systems Encoding / Interleaving Purpose: Interleaving is a simple, but powerful, method of reducing the effects of burst errors and recovering bits when burst errors occur. Example: In this example the symbols from each group are interleaved in a pattern that the receiver knows. The interleaver is located at the BTS and in the phone. Deinterleaving: Deinterleaving at the receiver will spread any burst errors that occur during transmission and make it simpler to decode. QUALCOMM Proprietary 3-23

92 Multiple Access Systems CDMA-050 Fundamentals of Wireless Communicaions & CDMA Coding and Spreading Tx Rx User 1 Data: 01 User 2 Data: 10 BTS Mobile User 1 Data: 01 User 1 Code: 0101 User 1 Code: 0101 User 2 Code: 0110 Figure 3-15 Spreading and Channelization 3-24 QUALCOMM Proprietary

93 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Multiple Access Systems Coding and Spreading Coding & spreading The encoded voice data is encoded using a code that will separate it from other encoded voice data. This process, known as channelization, will spread the encoded symbols over the entire bandwidth of the CDMA channel. Transmission The channelized data from all calls will be combined into a one signal that is transmitted is converted to an analog RF signal which is transmitted over the air. Receiver Decoding / Despreading The code used to channelize and spread the encoded voice data is known to the receiver. The receiver will use the code to despread/decode the signal and recover the encoded voice data. Codes used in CDMA Orthogonal (Walsh) codes are used on the forward link to channelize users. Pseudorandom noise (PN) code is used on the reverse link to channelize users. QUALCOMM Proprietary 3-25

94 Multiple Access Systems CDMA-050 Fundamentals of Wireless Communicaions & CDMA Digital to Analog Conversion Vocoded Voice Pulse Coded Demodulation (PCM) VOCODER A/D Figure 3-16 Voice Recovery 3-26 QUALCOMM Proprietary

95 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Multiple Access Systems Digital to Analog Conversion Deinterleaving and Decoding After the signal is despread the receiver will deinterleave and decode the signal into the original vocoded voice. The deinterleaving and decoding is done at the BTS and in the phone. Voice Decompression The decompression of the voice signal is done at the BSC and then sent to the PSTN. Voice Recovery The receiver converts the vocoded voice into an analog voice signal. The D/A conversion is done at the PSTN. QUALCOMM Proprietary 3-27

96 Multiple Access Systems CDMA-050 Fundamentals of Wireless Communicaions & CDMA Forward Link Channels Pilot Σ Sync Paging Traffic... Traffic Figure 3-17 Forward Link Channels 3-28 QUALCOMM Proprietary

97 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Multiple Access Systems Forward Link Channels Code Channels A channel is a stream of data designated for a specific use or person and is separated by a code. A channel may be voice data or overhead control data. Forward Link Channels On the forward link there are 4 channels used to transmit control and voice data to the mobile. These code channels are: Pilot Sync Paging Traffic QUALCOMM Proprietary 3-29

98 Multiple Access Systems CDMA-050 Fundamentals of Wireless Communicaions & CDMA Forward Link Channels Pilot Σ Sync Paging Traffic... Traffic Figure 3-18 Pilot Channel Pilot Σ Sync Paging Traffic... Traffic Figure 3-19 Sync Channel 3-30 QUALCOMM Proprietary

99 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Multiple Access Systems Forward Link Channels Pilot Channel The pilot channel is constantly transmitted. The mobile uses the pilot signal to acquire the system. After the mobile has acquired the system the pilot is used for signal strength measurement. The strength of the pilot is used to determine the power required for mobile transmit. The pilot contains no information but the it is the strongest signal on the forward link, containing at least 20% of the total power on the forward link. Sync Channel The sync channel is constantly transmitted providing critical timing information to the mobile. The mobile will decode the sync channel message during the power up sequence. Once the mobile is synchronized with the base station the sync channel is ignored. QUALCOMM Proprietary 3-31

100 Multiple Access Systems CDMA-050 Fundamentals of Wireless Communicaions & CDMA Forward Link Channels Pilot Σ Sync Paging Traffic.. Traffic. Figure 3-20 Paging Channel Pilot Σ Sync Paging Traffic. Traffic.. Figure 3-21 Forward Traffic Channel 3-32 QUALCOMM Proprietary

101 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Multiple Access Systems Forward Link Channels Paging Channel The paging channel is used to transmit overhead information (i.e. commands and pages) to the mobile. When a call is being set up the commands and traffic channel assignment are sent on the paging channel. Once a traffic channel is established the paging channel is ignored by the mobile. Forward Traffic Channel The forward traffic channel is used when there is a call. Voice data and control overhead information, normally sent on the paging channel, are transmitted to the mobile on the traffic channel. QUALCOMM Proprietary 3-33

102 Multiple Access Systems CDMA-050 Fundamentals of Wireless Communicaions & CDMA Reverse Link Channels Traffic Traffic Traffic Access Figure 3-22 Reverse Link Channels 3-34 QUALCOMM Proprietary

103 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Multiple Access Systems Reverse Link Channels On the reverse link there are 2 types of channels used to transmit control and voice data to the mobile. These channels are: Access Traffic QUALCOMM Proprietary 3-35

104 Multiple Access Systems CDMA-050 Fundamentals of Wireless Communicaions & CDMA Reverse Link Channels Figure 3-23 Access & Traffic Channel 3-36 QUALCOMM Proprietary

105 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Multiple Access Systems Reverse Link Code Channels Access Channel The access channel is used by the mobile when not assigned to a traffic channel. The access channel is used by the mobile to register with the network, originate calls, respond to pages and commands from the base station, and transmit overhead messages to the base station. Reverse Traffic Channel The reverse traffic channel is used when there is a call. Voice data and control overhead information, normally sent on the access channel, are transmitted to the base station on this channel. QUALCOMM Proprietary 3-37

106 Multiple Access Systems CDMA-050 Fundamentals of Wireless Communicaions & CDMA Call Processing Initialization Idle Mode Access Mode Traffic Mode Figure 3-24 Call Processing 3-38 QUALCOMM Proprietary

107 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Multiple Access Systems Call Processing Initialization Mode Mobile acquires system via Pilot code channel. Mobile synchronizes with system via Sync code channel. Idle Mode Mobile and base station communicate over Access and Paging code channels when NOT involved in a call. Mobile obtains overhead information via the Paging code channel. Access Mode Mobile accesses the network via the Access code channel Traffic Mode Land to mobile call When a call for a mobile is placed the mobile will receive a page on the Paging channel. The mobile responds on the Access channel and Traffic channels are established. Mobile to land call When a call is placed from a mobile the call is placed using the Access channel. The base station responds on the Paging channel and Traffic channels are established. QUALCOMM Proprietary 3-39

108 Multiple Access Systems CDMA-050 Fundamentals of Wireless Communicaions & CDMA Roaming Figure 3-25 Roaming 3-40 QUALCOMM Proprietary

109 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Multiple Access Systems Roaming Definition Wireless phones are programmed to operate in a specific system, called the home system. A phone operating in a non-home system is said to be a roamer. Roaming charges A user may be charged an additional fee for accessing the network. The fees are established by the service providers and any agreement they may have between them. QUALCOMM Proprietary 3-41

110 Multiple Access Systems CDMA-050 Fundamentals of Wireless Communicaions & CDMA Section Summary Multiple Access Systems CDMA Channel Generation CDMA Channels Figure 3-26 Section Summary 3-42 QUALCOMM Proprietary

111 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Multiple Access Systems Section Summary List the techniques used in multiple access systems. Describe the 5 steps to generate a CDMA signal. List the purpose for each channel in a CDMA system. QUALCOMM Proprietary 3-43

112 Multiple Access Systems CDMA-050 Fundamentals of Wireless Communicaions & CDMA Comments/Notes 3-44 QUALCOMM Proprietary

113 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Features of CDMA Section 4 Features of CDMA QUALCOMM Proprietary 4-1

114 Features of CDMA CDMA-050 Fundamentals of Wireless Communicaions & CDMA Section Introduction Universal Frequency Reuse Power Control Soft Handoff Figure 4-1 Section Introduction 4-2 QUALCOMM Proprietary

115 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Features of CDMA Section Introduction In this section the following topics will be discussed: Universal Frequency Reuse Power Control Handoffs QUALCOMM Proprietary 4-3

116 Features of CDMA CDMA-050 Fundamentals of Wireless Communicaions & CDMA Section Objectives List the features of CDMA. Describe the purpose for frequency reuse. Describe the purpose for power control. Describe the type of handoffs in CDMA. Figure 4-2 Section Objectives 4-4 QUALCOMM Proprietary

117 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Features of CDMA Section Objectives The objectives of the this section are to: List the features of CDMA. Describe the purpose of Frequency reuse. Describe the purpose for power control. Describe the type of handoffs in CDMA. QUALCOMM Proprietary 4-5

118 Features of CDMA CDMA-050 Fundamentals of Wireless Communicaions & CDMA Frequency Planning Requirement B C A Figure 4-3 Cell Interference 4-6 QUALCOMM Proprietary

119 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Features of CDMA Frequency Planning Requirement Cell Interference If cell A and B were on the same frequency in a conventional cellular systems, area C would have a frequency conflict and interference. With the deployment of a FDMA network channel (frequency) reuse is required. In the FDMA system there is a conflict when adjacent cells use the same channel (frequency). QUALCOMM Proprietary 4-7

120 Features of CDMA CDMA-050 Fundamentals of Wireless Communicaions & CDMA FDMA & TDMA Frequency Planning E F D C B E F G C B D A G C F D A B E F D C B E A G C B Figure 4-4 Frequency Reuse of QUALCOMM Proprietary

121 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Features of CDMA FDMA & TDMA Frequency Planning Frequency Reuse of 7 To avoid conflict between cells, FDMA and TDMA systems use a reuse factor of seven (six cells surrounding each cell cannot use the same frequency). Adjacent cells will be assigned to separate channels (frequencies). As capacity requirements increase additional cells will be added to the network creating a reworking of the frequency plan in the network. Cell Separation A channel (frequency) can be used again within the network but cells using the same channel must be separated by an appropriate distance. QUALCOMM Proprietary 4-9

122 Features of CDMA CDMA-050 Fundamentals of Wireless Communicaions & CDMA CDMA Frequency Planning A A A A A A A A A A A A A A A A A A A A A A A A A A A A Figure 4-5 Universal Frequency Reuse 4-10 QUALCOMM Proprietary

123 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Features of CDMA CDMA Frequency Planning CDMA Universal Frequency Reuse CDMA has a frequency reuse of one. Each BTS in the network uses the same frequency eliminating the need for frequency planning. QUALCOMM Proprietary 4-11

124 Features of CDMA CDMA-050 Fundamentals of Wireless Communicaions & CDMA Problems in a CDMA Channel Figure 4-6 CDMA Channel Issues 4-12 QUALCOMM Proprietary

125 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Features of CDMA Problems in a CDMA Channel Near-Far Problem If all mobiles transmitted at the same power level, signals received by the base station from mobiles further away would be weaker than those signals received from mobiles which were closer to the cell. This issue reduces, if not resolved, the capacity of a CDMA system. Path Loss The more distance between the cell and a phone the weaker the signal becomes. Fading Fading occurs when more than two signals from the same transmitter are received due to multipath. QUALCOMM Proprietary 4-13

126 Features of CDMA CDMA-050 Fundamentals of Wireless Communicaions & CDMA Reverse Link Power Control Figure 4-7 Mobile Power Control 4-14 QUALCOMM Proprietary

127 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Features of CDMA Reverse Link Power Control Power Control The objective of power control is to ensure that signals from all mobiles are received at the Base Station with the same received power. The CDMA network independently controls the power of each mobile. Open Loop Open loop is a estimate of what power the phone should use to transmit. The estimate is determined based on the strength of the mean signal power received by the mobile. Fast Closed Loop Fast closed loop is used when there is a call. The network will send a command to the mobile to either increase or decrease power. The command is determined on the quality of the information received at the BTS. QUALCOMM Proprietary 4-15

128 Features of CDMA CDMA-050 Fundamentals of Wireless Communicaions & CDMA Forward Link Power Control PSTN BSC BTS BTS Figure 4-8 Base Station Power Control 4-16 QUALCOMM Proprietary

129 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Features of CDMA Forward Link Power Control The BTS independently adjusts the power for each forward traffic channel based on information received from the mobile. QUALCOMM Proprietary 4-17

130 Features of CDMA CDMA-050 Fundamentals of Wireless Communicaions & CDMA Multipath BSC Figure 4-9 CDMA and Multipath 4-18 QUALCOMM Proprietary

131 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Features of CDMA Multipath What is multipath? Signals sent over the air can take a direct path to the mobile, bounce off objects, and arrive at the mobile s antenna at different times. These different paths are referred to as multi-paths. Effects of multipath signals Multipath signals in a narrow band signal, such as FDMA and TDMA, may cause a loss of the signal through cancellation. Multipaths in CDMA can be used to increase the quality of the signal. This is possible because CDMA is a wideband signal. CDMA advantage Better voice quality. Reduces power requirement to maintain link. QUALCOMM Proprietary 4-19

132 Features of CDMA CDMA-050 Fundamentals of Wireless Communicaions & CDMA CDMA Receiver Figure 4-10 Rake Receiver 4-20 QUALCOMM Proprietary

133 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Features of CDMA CDMA Receiver Rake Receiver The rake receiver is multiple receivers in one. There is a rake receiver at both the mobile and BTS. Each receiver may assigned to a received signal. QUALCOMM Proprietary 4-21

134 Features of CDMA CDMA-050 Fundamentals of Wireless Communicaions & CDMA What is a Handoff? Cell Cell Figure 4-11 Handoff 4-22 QUALCOMM Proprietary

135 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Features of CDMA What is a Handoff? Why Handoff? Handoffs are necessary to continue the call as the phone travels. Handoff describes the process of transferring a call from one cell to another. Handoff Overview As the phone moves through a network the system controller transfers the call from one cell to another, this process is called handoff. Handoffs maybe done with the assistance of the mobile or the system controller will control the process by itself. QUALCOMM Proprietary 4-23

136 Features of CDMA CDMA-050 Fundamentals of Wireless Communicaions & CDMA Handoffs Cell B Cell A Cell B Cell A Figure 4-12 Handoff Process 4-24 QUALCOMM Proprietary

137 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Features of CDMA Handoffs Break-Before-Make In a hard handoff, the mobile must disconnect (or break) its connection before connecting to the new cell. As the mobile moves from one coverage area to another, the mobile will be instructed to change to the new network. Advantages of Hard Handoff Continue the call beyond the current network. Provide expanded service. Reduce dropped calls. Overlay and integration of new CDMA networks with the existing networks. QUALCOMM Proprietary 4-25

138 Features of CDMA CDMA-050 Fundamentals of Wireless Communicaions & CDMA Types of CDMA Handoff PSTN BSC BTS BTS PSTN MTSO BSC Figure 4-13 CDMA Handoffs 4-26 QUALCOMM Proprietary

139 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Features of CDMA Types of CDMA Handoff Soft Handoffs Soft handoffs occur when the mobile is involved in a call. CDMA uses the mobile to assist the network in the handoff. The term soft handoff is used to describe the make-before-break process which takes place during the handoff. Soft handoffs occur between cells, sectors in a cell, or combination of cells and sectors. Hard Handoffs Hard handoffs occur when the mobile is involved in a call. During a hard handoff a CDMA phone is not able to assist the network in the handoff. The term hard handoff is used to describe the break-before-make process that occurs during the handoff. Hard handoffs occur between CDMA to Analog systems. Idle Handoff Idle handoffs occur when the mobile is NOT involved in a call. The idle handoff does not require any interaction between the phone and the base station. Used in CDMA mode only. QUALCOMM Proprietary 4-27

140 Features of CDMA CDMA-050 Fundamentals of Wireless Communicaions & CDMA Soft Handoff Cell B Cell A Cell B Cell A Cell B Cell A Figure 4-14 Soft Handoff 4-28 QUALCOMM Proprietary

141 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Features of CDMA Soft Handoff Make-Before-Break A new connection can be made prior to breaking the old connection. This is possible because CDMA cells use the same frequency and the mobile uses a rake receiver. In a CDMA system, while a call is in progress, the mobile assists the network in making a new connection before breaking the old connection. As the mobile moves from one coverage area to another, the mobile detects a new pilot and the base station establishes a new connection for the mobile. A communications link is established with new BTS while the old link is maintained. Advantages of Soft Handoff Reduces interference. Increases capacity. No dropped calls. Improves voice quality. QUALCOMM Proprietary 4-29

142 Features of CDMA CDMA-050 Fundamentals of Wireless Communicaions & CDMA Softer Handoff BSC one voice frame Backhaul BTS Decoded & Combined Figure 4-15 Softer Handoff 4-30 QUALCOMM Proprietary

143 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Features of CDMA Softer Handoff Softer Handoff Involves 2 sectors from the same BTS. The BTS will decode and combines the voice signal received from each sector and forward the combined voice frame to the selector at the BSC. Soft-Softer Handoff A soft-softer handoff is a combination of multiple cells and multiple sectors in one cell. QUALCOMM Proprietary 4-31

144 Features of CDMA CDMA-050 Fundamentals of Wireless Communicaions & CDMA CDMA Hard Handoff FDMA (Analog) MTSO CDMA BSC Figure 4-16 CDMA to Analog Hard Handoff 4-32 QUALCOMM Proprietary

145 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Features of CDMA CDMA to Analog Hard Handoff CDMA to Analog A mobile using CDMA in a cellular system can also handoff to a FDMA (analog) system. Pilot Beacon Units (PBU) can be placed at the analog cell site. The PBU is used to alert the phone that the edge of CDMA coverage has been reached and to conduct a hard handoff. Following a call where a hard handoff has occurred the phone will attempt to acquire a CDMA network. If none is available the phone will switch to analog mode. This type of handoff is only available in the cellular band. Analog to CDMA This option is not available. QUALCOMM Proprietary 4-33

146 Features of CDMA CDMA-050 Fundamentals of Wireless Communicaions & CDMA Idle Handoff BTS Access Pilot Paging Pilot BTS Figure 4-17 Idle Handoff 4-34 QUALCOMM Proprietary

147 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Features of CDMA Idle Handoff Idle Handoffs The mobile monitors the pilot of a BTS while searching for the pilots from the neighboring BTSs. When the mobile detects a pilot that is stronger than the current pilot an idle handoff is performed without the assistance of the base station. QUALCOMM Proprietary 4-35

148 Features of CDMA CDMA-050 Fundamentals of Wireless Communicaions & CDMA Section Summary Universal Frequency Reuse Power Control Soft Handoff Figure 4-18 Section Summary 4-36 QUALCOMM Proprietary

149 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Features of CDMA List the features of CDMA. Section Summary Describe the purpose of Frequency reuse. Describe the purpose for power control. Describe the type of handoffs in CDMA. QUALCOMM Proprietary 4-37

150 Features of CDMA CDMA-050 Fundamentals of Wireless Communicaions & CDMA Comments/Notes 4-38 QUALCOMM Proprietary

151 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Advantages of CDMA Section 5 Advantages of CDMA QUALCOMM Proprietary 5-1

152 Advantages of CDMA CDMA-050 Fundamentals of Wireless Communicaions & CDMA Section Introduction Coverage Capacity Clarity Cost Compatibility Customer Satisfaction Figure 5-1 Section Introduction 5-2 QUALCOMM Proprietary

153 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Advantages of CDMA Section Introduction In this section the following topics will be discussed: Coverage Capacity Clarity Cost Compatibility Customer Satisfaction QUALCOMM Proprietary 5-3

154 Advantages of CDMA CDMA-050 Fundamentals of Wireless Communicaions & CDMA Section Objectives List the advantages CDMA has over other technologies. Describe the advantages CDMA has over other technologies. Figure 5-2 Section Objectives 5-4 QUALCOMM Proprietary

155 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Advantages of CDMA Section Objectives The objectives of the this section are to: List the advantages CDMA has over other technologies. Describe the advantages CDMA has over other technologies. QUALCOMM Proprietary 5-5

156 Advantages of CDMA CDMA-050 Fundamentals of Wireless Communicaions & CDMA FDMA / TDMA / CDMA Coverage FDMA TDMA CDMA Figure 5-3 Coverage 5-6 QUALCOMM Proprietary

157 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Advantages of CDMA Coverage Coverage Issues Providing adequate coverage is a basic requirement of a wireless system. Coverage of a BTS or network is impacted by the capacity requirements of the system, terrain of the area, and power of the base station and mobiles. CDMA Advantage Forward and reverse link power control helps a CDMA network dynamically expand the coverage area. The coding and interleaving techniques used in CDMA provide the ability to cover a larger area for the same amount of available power used in other systems. Under line of sight conditions CDMA has a 1.7 to 3 times more coverage than TDMA. QUALCOMM Proprietary 5-7

158 Advantages of CDMA CDMA-050 Fundamentals of Wireless Communicaions & CDMA Capacity CDMA TDMA Analog Figure 5-4 CDMA Capacity 5-8 QUALCOMM Proprietary

159 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Advantages of CDMA Capacity CDMA Capacity with 8k Vocoder For cellular and PCS a CDMA system may have a capacity of 22 simultaneous calls per sector. When the BTS has 3 sectors 66 simultaneous calls can be accommodated on 1.25 MHz of spectrum. For wireless local loop a CDMA system may have a capacity of 45 simultaneous calls per sector. When the BTS has 3 sectors 135 simultaneous calls can be accommodated on 1.25 MHz of spectrum. CDMA Capacity with 13k Vocoder For cellular and PCS a CDMA system may have a capacity of 14 simultaneous calls per sector. When the BTS has 3 sectors 42 simultaneous calls can be accommodated. For wireless local loop a CDMA system may have a capacity of 30 simultaneous calls per sector. When the BTS has 3 sectors 90 simultaneous class can be accommodated. FDMA capacity An FDMA system can have only 6 calls for the same amount of spectrum used by one CDMA channel. TDMA capacity An IS-54 TDMA system can have only 18 calls for the same amount of spectrum used by one CDMA channel. QUALCOMM Proprietary 5-9

160 Advantages of CDMA CDMA-050 Fundamentals of Wireless Communicaions & CDMA Soft Handoff Hard handoff region Soft handoff region Figure 5-5 Soft Handoff 5-10 QUALCOMM Proprietary

161 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Advantages of CDMA Advantages of Soft Handoff Capacity of a system is reduced when more power is required to communicate with a mobile. The soft handoff and power control in CDMA reduces the power requirements of a call allowing more users in the system. Hard handoff boundary Typically occur farther away from the serving base station requiring more power. Soft handoff boundary Occurs closer to the previous base station which results in less power required to maintain the link. Advantage Greater capacity Better voice quality QUALCOMM Proprietary 5-11

162 Advantages of CDMA CDMA-050 Fundamentals of Wireless Communicaions & CDMA Clarity Variable Rate Vocoder Rake Receiver Power Control Soft Hand-off Wide Band Signal Encoding and Interleaving Figure 5-6 Clarity 5-12 QUALCOMM Proprietary

163 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Advantages of CDMA Clarity Rake Receiver Combines multipath and softer handoff signals to reduce errors and power requirements. Variable Rate Vocoder The dynamic rate of the vocoder reduces the amount of data transmitted for each person and reduces the interference. Soft Hand-off The soft hand off in CDMA reduces the interference and power requirements for maintaining the link. Multiple received signals can be combined to reduce the possibility of errors resulting from interference and fading. Power Control Dynamic power control reduces errors by keeping the power at an optimal level. Wideband Signal CDMA s wideband signals does not suffer from the same effects of fading experience in an FDMA or TDMA system. Encoding and Interleaving Strong encoding and interleaving reduces the effects of fading. QUALCOMM Proprietary 5-13

164 Advantages of CDMA CDMA-050 Fundamentals of Wireless Communicaions & CDMA USA Network Cost Cellular Infrastructure Cost / Subscriber $ Analog GSM/TDMA CDMA Year Table 5-1 Cellular Infrastructure Cost PCS Infrastructure Cost / Subscriber $ TDMA GSM CDMA Year Table 5-2 PCS Infrastructure Cost 5-14 QUALCOMM Proprietary

165 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Advantages of CDMA USA Network Cost Cell Coverage Because of increased coverage for each BTS in a wireless network fewer BTSs are required in the network to cover a given area. More subscribers CDMA can support more subscribers in a system, increasing the service providers revenue potential. QUALCOMM Proprietary 5-15

166 Advantages of CDMA CDMA-050 Fundamentals of Wireless Communicaions & CDMA Compatibility Data Transmission Dual Mode Phone Standard for Cellular Dual Band-Dual Mode Phone Digital Duck Figure 5-7 CDMA Compatibility 5-16 QUALCOMM Proprietary

167 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Advantages of CDMA Compatibility Data Transmission Data transmission is easier in CDMA because of the continual transmission capabilities. Dual Mode Phone Standard for Cellular The phones manufactured for CDMA are designed to work in the cellular analog mode as well as CDMA mode. Dual Band-Dual Mode Phones CDMA phones can be designed to work in both the cellular and the PCS bands since CDMA has been accepted for operation in both bands. QUALCOMM Proprietary 5-17

168 Advantages of CDMA CDMA-050 Fundamentals of Wireless Communicaions & CDMA Customer Satisfaction Voice Quality Battery Life No Cross-Talk Privacy Figure 5-8 Customer Satisfaction 5-18 QUALCOMM Proprietary

169 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Advantages of CDMA Customer Satisfaction Voice Quality Market reports state that voice quality will be the leading contribution to the increased popularity of CDMA (Wireless Communications Industry, Spring 1997; Donaldson, Lufkin & Jenrette). Battery Life Because of the reduced power requirements the battery in a CDMA portable will last longer. No Cross-Talk Because of the coding in a CDMA call the cross-talk is eliminated. Privacy CDMA coding tremendously reduces the possibility of obtaining phone data over the air while providing a more secure conversation. QUALCOMM Proprietary 5-19

170 Advantages of CDMA CDMA-050 Fundamentals of Wireless Communicaions & CDMA Section Summary Coverage Capacity Clarity Cost Compatibility Customer Satisfaction Figure 5-9 Section Summary 5-20 QUALCOMM Proprietary

171 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Advantages of CDMA Section Summary List the advantages CDMA has over other technologies. Describe the advantages CDMA has over other technologies. QUALCOMM Proprietary 5-21

172 Advantages of CDMA CDMA-050 Fundamentals of Wireless Communicaions & CDMA Comments/Notes 5-22 QUALCOMM Proprietary

173 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Future of Wireless Communication Section 6 Future Of Wireless Communication QUALCOMM Proprietary 6-1

174 Future of Wireless Communication CDMA-050 Fundamentals of Wireless Communicaions & CDMA Section Introduction Trends in the Wireless Markets Data Services Wireless Local Loop Globalstar Figure 6-1 Section Introduction 6-2 QUALCOMM Proprietary

175 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Future of Wireless Communication Section Introduction In this section the following topics will be discussed: Trends in the Wireless Markets Data Services Wireless Local Loop Globalstar QUALCOMM Proprietary 6-3

176 Future of Wireless Communication CDMA-050 Fundamentals of Wireless Communicaions & CDMA Section Objectives Describe the future of wireless. Describe the data services available in CDMA. Describe the application of CDMA to wireless local loop and Globalstar. Figure 6-2 Section Objectives 6-4 QUALCOMM Proprietary

177 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Future of Wireless Communication Section Objectives The objectives of the this section are to: Describe the future of wireless. Describe the data services available in CDMA. Describe the application of CDMA to wireless local loop and Globalstar. QUALCOMM Proprietary 6-5

178 Future of Wireless Communication CDMA-050 Fundamentals of Wireless Communicaions & CDMA CDMA Commercial / Deployments or Trials Figure 6-3 The World of CDMA CDG Home Page: QUALCOMM Proprietary

179 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Future of Wireless Communication CDMA Commercial / Deployments or Trials Cellular PCS WLL Trials Asia-Pacific: China; Europe-Russia: Germany, Poland, United Kingdom; Middle East: Israel; South America: Argentina, Brazil, Peru, Venezuela; South America: Chile; Asia-Pacific: China; South America: Brazil; Commercial / Deployments Africa: Congo, Zambia; Asia-Pacific: Hong Kong, Indonesia, Japan, Korea, Philippines, Thailand; Europe-Russia: Russia; North America: Canada, Domnican Republic; South America: Peru; United States: over 30 major markets; Asia-Pacific: Korea; North America: Canada United States: over 50 major markets; Table 6-1 CDMA Commercial / Deployments or Trails Africa: Nigeria; Middle East: Yemen; North America: Domnican Republic; QUALCOMM Proprietary 6-7

180 Future of Wireless Communication CDMA-050 Fundamentals of Wireless Communicaions & CDMA World Wireless Subscribers World Wireless Market 500, , ,000 No. of Subscribers in Thousand 350, , , , , ,000 Total 50, Year Figure 6-4 Wireless Subscribers 6-8 QUALCOMM Proprietary

181 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Future of Wireless Communication World Wireless Subscribers In 1997 there were over 150 million wireless subscribers, outside of the USA. In the next 4 years the growth of wireless subscribers, outside of the USA, is expected reach 500 million. In 1997, after two (2) years of CDMA deployments, 16% of subscribers outside of the USA were using CDMA. The growth of CDMA subscribers in the 3rd year of commercial services is expected to be 248% while GSM subscribers are expected to grow by 60%. The number of wireless subscriber in the USA, in 1997, was over 50 million. During the next 4 years the number of subscribers is expected to be over 95 million people. During the next decade it is expected that almost 50% of the people in America will own a wireless phone. Cellular The rate of growth for digital service will grow with the greatest growth being in CDMA. This growth is possible because of the ability to overlay CDMA on existing FDMA networks and migrate from FDMA to CDMA over time. PCS PCS service is rapidly growing as service providers deploy their networks. The deployments of CDMA networks will be expediential in comparison to other technologies. Following the PCS auctions in 1997, 37% of all licenses selected CDMA while 30% selected TDMA technologies such as GSM or TDMA (IS-136). The remaining 33% were not yet decided. Cellular vs. PCS It is expected that about 65% of all wireless customers, in the next decade, will subscribe to cellular service. QUALCOMM Proprietary 6-9

182 Future of Wireless Communication CDMA-050 Fundamentals of Wireless Communicaions & CDMA Wireless Data Services Figure 6-5 CDMA Data Services Modes CDMA digital, analog, and wireline Speed Land line 33.6 kbps Wireless upto 2 Mbps Protocol TCP/IP Voice and data mixed 6-10 QUALCOMM Proprietary

183 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Future of Wireless Communication Wireless Data Services By the year 2000 approximately 8 million users will be using data services. Current Wireless Data Services Currently there are two types of data services available: 1) Modems using ordinary voice cellular (most popular); 2) Custom cellular protocols (i.e. cellular digital packet data (CDPD) or GSM data). CDMA Data Services Modes The Data on the Go Fax/Modem Card senses the type of connection needed and automatically switches between CDMA digital and analog cellular service depending upon the operating mode of the phone. Wireline mode is enabled by simply connecting the standard telephone adapter cable (RJ-11) to the Data on the Go Fax/Modem Card. Speed Wireline: 33.6 Kbps. CDMA mobile: 144 Kbps CDMA walking: 384 Kbps CDMA WLL: 2 Mbps Protocol CDMA digital fax and data services are based on industry standard (TCP/IP) protocols. CDMA packet data-capable CDMA data services will grow to take advantage of future packet service features such as the ability to receive data while simultaneously talking on your phone. QUALCOMM Proprietary 6-11

184 Future of Wireless Communication CDMA-050 Fundamentals of Wireless Communicaions & CDMA Wireless Local Loop (WLL) BSC Wireless Local Loop BTS PSTN Local Loop Figure 6-6 Wireless Local Loop 6-12 QUALCOMM Proprietary

185 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Future of Wireless Communication Wireless Local Loop (WLL) Many countries throughout the world do not have an extensive telephone system. Wireless local loop system is a cost effective solution. Local Loop is the wireline connection between the PSTN and a phone. Wireless Local Loop has no wires connecting the phone to the PSTN. Telecom competition has created a need for alternatives to wireline local loop systems. Traditional wireline systems are expensive, inflexible and have limited capabilities. Alternatives to wireline systems must be able to meet subscriber and operator demands. Subscribers demand comparable quality and service levels as wireline. Operators demand flexible and cost-effective alternatives to wireline. CDMA wireless local loop is a viable and cost-effective alternative to wireline with the capability for rapid deployment, flexible capacity planning, and competitive economics. QUALCOMM Proprietary 6-13

186 Future of Wireless Communication CDMA-050 Fundamentals of Wireless Communicaions & CDMA QUALCOMM Wireless Local Loop Subscribers Figure 6-7 QCT-6000 / 6200 Figure 6-8 QCT-1000 / QUALCOMM Proprietary

187 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Future of Wireless Communication QUALCOMM Wireless Local Loop Subscribers QCT-6000: Cellular band / QCT-62000: PCS band Allows multiple wireline connections. Provides voice, fax, and data connections. Optional panel antenna that can be externally mounted. QCT-1000: cellular band / QCT-1200: PCS band Provides the ability for phone service in places landlines can t be installed -- like some business and residential areas, boats and RVs. Land line phone services. Optional panel antenna that can be externally mounted. QUALCOMM Proprietary 6-15

188 Future of Wireless Communication CDMA-050 Fundamentals of Wireless Communicaions & CDMA Wireless Local Loop Market Telephone lines per 100 inhabitants Figure 6-9 Telephone Lines per Population 6-16 QUALCOMM Proprietary

189 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Future of Wireless Communication Wireless Local Loop Market World Facts 4+ Billion people without phones. ~50 Million people on waiting lists for phones. Cost & time to provide wired service cannot support the needs of developing countries. Competition in the Local Loop The potential for alternative solutions to the wired local loop is enormous. Worldwide telephone penetration is less than 5% outside Europe and North America. There is a significant correlation between economic development and telecom development. Deregulation and liberalization of telecommunications are becoming the norm. The introduction of competition into mobile communication is relatively easy. The introduction of competition into fixed communications is less easy. QUALCOMM Proprietary 6-17

190 Future of Wireless Communication CDMA-050 Fundamentals of Wireless Communicaions & CDMA Wireless Local Loop Cost Comparison Figure 6-10 WLL Cost 6-18 QUALCOMM Proprietary

191 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Future of Wireless Communication Wireless Local Loop Cost Comparison The estimated cost per subscriber, for a WLL system, will be significantly lower than cellular or PCS. This is due to the increased capacity of a WLL system and the number of subscribers serviced. Higher capacity per carrier makes wireless local loop systems less expensive than PCS or cellular systems for equivalent usage. QUALCOMM Proprietary 6-19

192 Future of Wireless Communication CDMA-050 Fundamentals of Wireless Communicaions & CDMA Globalstar Figure 6-11 Globalstar Overview Globalstar home page: QUALCOMM Proprietary

193 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Future of Wireless Communication Globalstar Globalstar System and Services Globalstar system is a satellite-based, wireless telecommunications system designed to provide voice, data, fax, and other telecommunications services to users worldwide. Calls on the Globalstar System Users of Globalstar will make or receive calls using hand-held or vehicle mounted terminals similar to today s cellular phones. Calls will be relayed through the Globalstar satellite constellation, in a 1414 kilometer orbit above the Earth, to a ground station, and then through local terrestrial wireline and wireless systems to their end destinations. Services Cost Airtime is expected to cost about $0.50 to $0.60 per minute. Fixed Services Wireless local loop type applications. It is anticipated that 55% of its subscribers will be fixed services. Mobile Services Personal Services (hand held) The Globalstar/GSM Dual-mode User Terminal offers a global roaming solution for GSM cellular phone users. Globalstar enhances wireless service options by providing worldwide GSM cellular-like services in areas outside traditional cellular coverage. Inside the GSM service area subscriber may roam to other GSM cellular networks or switch to the Globalstar network. Inter-operability between Globalstar and GSM is assured and subscribers maintain a convenient single point for billing. QUALCOMM Proprietary 6-21

194 Future of Wireless Communication CDMA-050 Fundamentals of Wireless Communicaions & CDMA Globalstar Satellites Figure 6-12 Satellites Overview 6-22 QUALCOMM Proprietary

195 Fundamentals of Wireless Communicaions & CDMA CDMA-050 Future of Wireless Communication Globalstar Satellites The Globalstar satellite is a simple low cost satellite designed to minimize both satellite costs and launch costs. Globalstar satellites do not directly connect one Globalstar user to another. Rather, they relay communications between the user and a Gateway. The party being called will be connected with the Gateway through the Public Switch Telephone Network (thus maximizing the use of existing, low cost communications services) or back through a satellite if the party is another Globalstar user. 56 Globalstar satellites will be placed into low earth orbit, 48 of which will be operational, with eight orbital spares. The satellites will be placed in eight orbital planes of six satellites each with a 1,414 kilometer circular orbit inclined at 52 degrees. The satellite is three-axis stabilized and consists of a trapezoidal main body (configured to facilitate the launching of multiple satellites on one space launch vehicle), and two deployable solar arrays. The satellite mass is approximately 450 kilograms, and requires some 1,100 watts of power for normal operations. The satellites in the first-generation constellation are designed to operate at full performance for a minimum of 7 1/2 years. QUALCOMM Proprietary 6-23

196 Future of Wireless Communication CDMA-050 Fundamentals of Wireless Communicaions & CDMA Globalstar Gateway Figure 6-13 Gateway Overview 6-24 QUALCOMM Proprietary