Wireless Networked Systems

Wireless Networked Systems CS 795/895 - Spring 2013 Lec #7: Medium Access Control WPAN, Bluetooth, ZigBee Tamer Nadeem Dept. of Computer Science

Bluetooth Page 2 Spring 2013 CS 795/895 - Wireless Networked Systems

Overview Bluetooth is a specification for the use of low power wireless communications over short distance. Although Bluetooth standard utilizes the same 2.4 GHz range of Wi-Fi Compared to Wi-Fi, Bluetooth networking is slower, a bit more limited in range, and supports many fewer devices Page 3 Spring 2013 CS 795/895 - Wireless Networked Systems

History In 1994 need for low power consumption wireless devices to substitute for cable Ericsson driving force behind Bluetooth Pre-Cell phone 1998, Ericsson, Nokia, IBM, Toshiba, Intel formed the Bluetooth Special Interest Group (SIG) 1999 Release of Bluetooth protocol 2002 IEEE adopted Bluetooth standard, 802.15 working group Connections will be done seamlessly without need for installations and software drivers Devices can discover other Bluetooth-enabled devices Determine its capabilities and applications, and establish connections for data exchange Page 4 Spring 2013 CS 795/895 - Wireless Networked Systems

Bluetooth Usages Landline Cable Replacement Data/Voice Access Points Personal Ad-hoc Networks Page 5 Spring 2013 CS 795/895 - Wireless Networked Systems

Piconets / Scatternet Whenever there is a connection between two Bluetooth devices, a piconet is formed Always 1 master and up to 7 active slaves Any Bluetooth device can be either a master or a slave Can be a master of one piconet and a slave of another piconet at the same time (scatternet) Piconet uses centralized Time Division Multiplexing. All devices have the same timing and frequency hopping sequence Every Bluetooth device has its own clock and can be uniquely identified by its Bluetooth device address Slaves in a piconet use master's Bluetooth device address and clock to determine the frequency hopping sequence No time or frequency synchronization between piconets Page 6 Spring 2013 CS 795/895 - Wireless Networked Systems

Bluetooth Communication Bluetooth operates in unlicensed Industrial Scientific Medical (ISM) band at 2.4 GHz Band is divided into 79 channels with 1 MHz each Bluetooth devices use a Time-Division Duplex (TDD) scheme Channel is divided into consecutive slots (each 625 µs) One packet can be transmitted per slot Subsequent slots are alternatively used for transmitting and receiving Master can send only in EVEN slots while Slave can send only in ODD slots Page 7 Spring 2013 CS 795/895 - Wireless Networked Systems

Frequency Hopping Spread Spectrum (FHSS) Reduce interference, Bluetooth uses Frequency Hopping Spread Spectrum (FHSS) technology During a connection, radio transceivers hop from one channel to another 1600 hops per second through 79 1MHz channels One packet is sent on a channel, two devices then retune their frequencies (hop) to send the next packet on a different channel. So, if one frequency channel is blocked, limited disturbance to the Bluetooth communication Allows several Bluetooth networks to run concurrently without interrupting one other Link rate: 1 Mbps, but with overhead, this reduces to 721 kbps Typical range for Bluetooth is 10m, can reach up to 100m depending on the power class of the device Page 8 Spring 2013 CS 795/895 - Wireless Networked Systems

Bluetooth Protocol Stack The Baseband layer is responsible for channel coding and decoding Digitizes signals received by the radio for passing up the stack and it formats the data it receives from the Link Controller for transmission over the channel Host Controller Interface (HCI) defines uniform methods for accessing and controlling lower layers of the protocol stack, namely baseband and the link manager Link Manager Protocol (LMP) handles piconet management and link configuration. It also includes link security The Radio is the interface between the on-air channel medium and the Baseband The Link Controller is responsible for establishing and maintaining links between Bluetooth units Page 9 Spring 2013 CS 795/895 - Wireless Networked Systems

Bluetooth Protocol Stack Object Exchange Protocol (OBEX) is for object data exchange over infrared (IR) links Telephony Control Protocol Specification (TCS) defines call control signaling for establishing speech and data calls between Bluetooth devices, provides them with telephony services RFCOMM protocol defines a transport protocol for emulating RS-232 serial ports. Wireless Application Protocol (WAP) includes interoperability requirements for Bluetooth Service Discovery Protocol (SDP) defines procedures for discovering services of other devices as well as determining the characteristics of those services. Logical Link Control and Adaptation Protocol (L2CAP) provides connection-oriented and connectionless data services to the other higher level protocol layers Page 10 Spring 2013 CS 795/895 - Wireless Networked Systems

Bluetooth Transport Protocol Group " Radio Frequency (RF) " Baseband " Sending and receiving modulated bit streams " Defines the timing, framing " Flow control on the link. " Link Manager " Managing the connection states. " Enforcing Fairness among slaves. " Power Management " Logical Link Control & Adaptation Protocol " Handles multiplexing of higher level protocols " Segmentation & reassembly of large packets " Device discovery & QoS Page 11 Spring 2013 Bluetooth CS 795/895-11 Wireless Networked Systems

Bluetooth Middleware Protocol Group " Service Discovery Protocol (SDP) " TCP/IP " Means for applications to discover device info, services and its characteristics. " Network Protocols for packet data communication, routing " RFCOMM " Cable replacement protocol, emulation of serial ports over wireless network Page 12 Spring 2013 Bluetooth CS 795/895-12 Wireless Networked Systems

Physical Link Types " Synchronous Connection Oriented (SCO) " Point to Point Full Duplex between Master & Slave " Established once by master & kept alive till released by Master " Typically used for Voice connection ( to guarantee continuity ) " Master reserves slots used for SCO link on the channel to preserve time sensitive information " Asynchronous Connection Link (ACL) " It is a momentary link between master and slave. " No slots are reserved. " It is a Point to Multipoint connection. " Symmetric & Asymmetric links possible Page 13 Spring 2013 Bluetooth CS 795/895-13 Wireless Networked Systems

Bluetooth State Machine Page 14 Spring 2013 CS 795/895 - Wireless Networked Systems

Bluetooth State Machine " Inquiry Scan " Inquiry " A device that wants to be discovered will periodically enter this mode and listen for inquiry packets. " Device sends an Inquiry packet addressed to GIAC or DIAC " Transmission is repeated on the inquiry hop sequence of frequencies. " Inquiry Response " When an inquiry message is received in the inquiry scan state, a response packet (FHS) containing the responding device address must be sent after a random number of slots. Page 15 Spring 2013 Bluetooth CS 795/895-15 Wireless Networked Systems

Bluetooth State Machine " Page " The master uses the clock information, about the slave to be paged, to determine where in the hop sequence, the slave might be listening in the page scan mode. " The master sends a page message " Page Scan " The page scan substate can be entered by the slave from the standby state or the connection state. It listens to packets addressed to its DAC. " Page Response " On receiving the page message, the slave enters the slave page response substate. It sends back a page response consisting of its ID packet which contains its DAC, at the frequency for the next slot from the one in which page message was received. Page 16 Spring 2013 CS 795/895 - Wireless Networked Systems

Power Control Modes " Sniff Mode " This is a low power mode in which the listening activity of the slave is reduced. " In the sniff mode, the slave listens for transmissions only at fixed intervals T sniff, at the offset slot D sniff for N sniff times. These parameters are given by the master when it issues the SNIFF command to the slave. " Hold Mode " Slave temporarily (for T hold sec) does not support ACL packets on the channel (possible SCO links will still be supported). " By this capacity can be made free to do other things like scanning, paging, inquiring, or attending another piconet. " The slave unit keeps its active member address (AM_ADDR). Page 17 Spring 2013 Bluetooth CS 795/895-17 Wireless Networked Systems

Power Control Modes " Park Mode " This is a very low power mode with very little activity. " The slave however, stays synchronized to the channel. " The parked slaves regularly listen for beacon signals at intervals decided by the beacon structure communicated to the slave during the start of parking. " The parked slave has to be informed about a transmission in a beacon channel which is supported by the master to keep parked slaves in synchronization and send them any other information. " Any message to be sent to a parked member are sent over the broadcast channel. " It also helps the master to have more than seven slaves. Page 18 Spring 2013 Bluetooth CS 795/895-18 Wireless Networked Systems

Functional Overview Standby Waiting to join a piconet Unconnected Standby Standby Inquire Ask about radios to connect to Page Connect to a specific radio Connected Connecting States Active States Detach Transmit data AMA Inquiry T typical=2s Connected AMA Page T typical=0.6s Actively on a piconet (master or slave) T typical=2 ms T typical=2 ms Park/Hold Low Power connected states Low Power States Releases AMA Address PARK PMA HOLD AMA Page 19 Spring 2013 CS 795/895 - Wireless Networked Systems

Functional Overview Devices not connected to a piconet are in STANDBY mode, using low power. A connection is made by either a PAGE command if the address is known or by the INQUIRY command followed by a PAGE When a radio sends an INQUIRE command, all the listening radios respond with their FHS packets, which tells the inquiring radio of all the radios in the area. All listening radios perform a page scan and/or an inquiry scan every 1.25 seconds. The master radio sends an FHS to the paged radio. Page 20 Spring 2013 CS 795/895 - Wireless Networked Systems

Functional Overview When a radio joins a piconet it is assigned a 3 bit Active Member Address(AMA). Once the piconet has eight radios, the master assigns puts a radio into the PARK mode. This is one of the low power states, in which the radio releases its AMA for a 8 bit PMA (Passive Member Address). The freed AMA can be assigned to another radio wishing to join the piconet. Though upto 256 radios can actively reside on a piconet, only 8 of them with AMA s can transfer data. Page 21 Spring 2013 CS 795/895 - Wireless Networked Systems

Ex: Bluetooth Connection with a Device with Dial-up Service First, Bluetooth device looks for devices that it might connect to Step 1 - the Inquiry Process. Inquiring device, A, sends out an inquiry packet or repeated inquiry packets and waits to receive responses back Discoverable devices in range respond to an inquiry by sending a Frequency Hop Synchronization (FHS) packet, which contains all the information device A needs to connect to the responding device, including the Bluetooth device's address, page scan modes, and clock offset All devices that respond to the inquiry are reported to the host controller of device A. List of all devices discovered is presented to the user - is applicationdependent Page 22 Spring 2013 CS 795/895 - Wireless Networked Systems

Ex: Bluetooth Connection with a Device with Dial-up Service At this point, A knows which devices are in range, but it doesn t know which devices support dial-up Step 2 - Using information retrieved from inquiry, A now attempts to connect to different devices that responded to its inquiry in order to find out what services they support Depending on the application, device A may either 1) Establish links to all devices that responded to its inquiry and get information about their services and later on reconnect with one that supports dial-up networking; or 2) Upon seeing that a device supports dial-up networking, directly proceed to setting up a connection with that device without finding out the services from the rest of the devices in the list. In following slide, second option is adopted. Page 23 Spring 2013 CS 795/895 - Wireless Networked Systems

Ex: Bluetooth Connection with a Device with Dial-up Service Step 2 continued Device A wants to find out services of a device, so, device A sends out paging packets Connectable device will respond and a baseband link can be established between the two devices Following that, a L2CAP connection will be established before they can exchange service information. Information exchange is handled by Service Discovery Protocol Device B responds, I have dial-up networking service RFCOMM connection can then be established across the already existing L2CAP link After this, a dial-up networking connection can then be established on top of the RFCOMM connection Laptop can then start using the cell phone to access the phone network without any cables being needed for connections Page 24 Spring 2013 CS 795/895 - Wireless Networked Systems

Ex: Bluetooth Connection with a Device with Dial-up Service Step 1 Step 2 Page 25 Spring 2013 CS 795/895 - Wireless Networked Systems

Bluetooth Inquiry Process Uses 32 inquire channels to send out inquiry messages Send out inquiry on 32 channels, broken up into 2 inquiry hop trains (16 different channels to transmit packets) A device periodically listens for inquiry packets at a single frequency chosen out of 16 frequencies Stays in the state long enough for a inquiring device to cover 16 frequencies Receiver does an inquire scan frequent enough so that it is guaranteed to wake up during a 16 channel train Devices that allow themselves to be discoverable issue an inquiry response Will re-enter inquiry scan state even after responding to an inquire O D J F E I H A K G C B Note that a device can be Undiscoverable M L P N Q Page 26 Spring 2013 CS 795/895 - Wireless Networked Systems

Bluetooth Inquiry Process Each full scan of a 16 channel train takes about 1.28 seconds 16 channels * 625us * 128 trains = 1.28 seconds One full 16 channel train takes 10ms. Receiver enters inquiry scan state at least once every 1.28 seconds, and stays in that state for 10ms. The 128 train scan is repeated up to 4 times for each train (10.24 seconds), after which the inquiring device should know everyone nearby Page 27 Spring 2013 CS 795/895 - Wireless Networked Systems

Bluetooth Paging Process Step 1: Device broadcasts a page message out to the device that it wants to set up a connection with Does this in a similar manner as inquire messages (on 2 frequency trains of 16 frequencies each) Once the device receives a page response, it will stop paging Step 2: In the page response, an acknowledgement is sent back to the master containing the slave ID Step 3: In the master response, the frequency hopping generator is stopped and the master issues an FHS packet to the slave Step 4: The slave issues a final slave response transmission that is aligned to the slave s native clock Using the data from the FHS packet, the slave calculates adopts the master s frequency hopping pattern and synchronizes to its clock Page 28 Spring 2013 CS 795/895 - Wireless Networked Systems

Bluetooth Paging Process Step 5: When the master receives the packet, it jumps back to its frequency hopping pattern and assigns the slave an Active Member Address (AMA) for the piconet Master sends out a poll packet to ensure that the slave is on its frequency hopping pattern Step 6: Once the slave receives the poll packet, the slave replies with any kind of packet to ensure that it is on the right channel The acknowledgement must be received by the Master within the timeout period At the conclusion of step 6, a new synchronized connection is established between the master and the slave Page 29 Spring 2013 CS 795/895 - Wireless Networked Systems

Bluetooth Profiles Bluetooth is different from most network protocols. Most network protocols focus defining how the channels are to be used and leave application designers to define what they will be used for. Bluetooth V 1.1 defines 13 specific profiles (applications) that will be supported along with the different protocol stacks for each of them. Generic access profile provides secure channels between the master and slave. Service discovery profile allows devices to discover what services are available from other devices. Serial port profile for applications that need a serial port communication 30 Page 30 Spring 2013 CS 795/895 - Wireless Networked Systems

Bluetooth Profiles Generic object exchange profile provide support for the client/server model. note that a slave can be a client or a server. LAN access profile is a direct competitor of 802.11. allows a Bluetooth device to connect to a fixed network. Dialup access profile Ericsson s original motivation allows a notebook computer to communicate to a mobile phone without wires Fax profile allows fax machines to connect to mobile phones wirelessly to send and receive faxes 31 Page 31 Spring 2013 CS 795/895 - Wireless Networked Systems

Bluetooth Profiles Cordless Telephony Profile connect a cordless telephone handset to a base station without wires. Intercom profile allows two telephones to connect like walkie-talkies Headset Profile good for hands free telephony I.E. while driving a car The last three profiles are for wireless devices to exchange a wide variety of data Object Push profile for simple objects File transfer profile - general file transfer Synchronization profile - was designed to facilitate the exchange of data in both directions between a P.C. and a P.D.A. 32 Page 32 Spring 2013 CS 795/895 - Wireless Networked Systems

Interoperability & Profiles Represents default solution for a usage model Vertical slice through the protocol stack Basis for interoperability and logo requirements Each Bluetooth device supports one or more profiles Protocols Applications Profiles Page 33 Spring 2013 CS 795/895 - Wireless Networked Systems

Packet Structure 72 bits 54 bits 0-2744 bits Access Code Header Payload Voice header Data CRC No CRC No retries FEC (optional) ARQ FEC (optional) Page 34 Spring 2013 Bluetooth CS 795/895-34 Wireless Networked Systems

Zigbee Page 35 Spring 2013 CS 795/895 - Wireless Networked Systems

The ZigBee Alliance Solution Targeted at home and building automation and controls, consumer electronics, PC peripherals, medical monitoring, and toys Industry standard through application profiles running over IEEE 802.15.4 radios Primary drivers are simplicity, long battery life, networking capabilities, reliability, and cost Alliance provides interoperability and certification testing Page 36 Spring 2013 CS 795/895 - Wireless Networked Systems

The Wireless Market SHORT < RANGE > LONG TEXT GRAPHICS INTERNET ZigBee HI-FI AUDIO Bluetooth 2 Bluetooth1 STREAMING VIDEO 802.11b DIGITAL VIDEO MULTI-CHANNEL VIDEO 802.11a/HL2 & 802.11g LAN PAN LOW < DATA RATE > HIGH Page 37 Spring 2013 CS 795/895 - Wireless Networked Systems

Applications security HVAC AMR lighting control access control BUILDING AUTOMATION CONSUMER ELECTRONICS TV VCR DVD/CD remote patient monitoring fitness monitoring PERSONAL HEALTH CARE ZigBee Wireless Control that Simply Works PC & PERIPHERALS mouse keyboard joystick asset mgt process control environmental energy mgt INDUSTRIAL CONTROL RESIDENTIAL/ LIGHT COMMERCIAL CONTROL security HVAC lighting control access control lawn & garden irrigation Page 38 Spring 2013 CS 795/895 - Wireless Networked Systems

IEEE 802.15.4 & ZigBee In Context Application Customer API Security 32- / 64- / 128-bit encryption Network Star / Mesh / Cluster-Tree MAC PHY 868MHz / 915MHz / 2.4GHz Silicon Stack App ZigBee Alliance IEEE 802.15.4 the software Network, Security & Application layers Brand management IEEE 802.15.4 the hardware Physical & Media Access Control layers Page 39 Spring 2013 CS 795/895 - Wireless Networked Systems

Development of the Standard APPLICATIONS APPLICATION INTERFACE SECURITY NETWORK LAYER Star/Cluster/Mesh MAC LAYER MAC LAYER PHY LAYER 2.4 GHz 915MHz 868 MHz Application ZigBee Stack Customer IEEE 802.15.4 ZigBee Alliance Silicon ZigBee Alliance 50+ companies: semiconductor mfrs, IP providers, OEMs, etc. Defining upper layers of protocol stack: from network to application, including application profiles First profiles published mid 2003 IEEE 802.15.4 Working Group Defining lower layers of protocol stack: MAC and PHY scheduled for release in April Page 40 Spring 2013 CS 795/895 - Wireless Networked Systems

Stack Reference Model End developer applications, designed using application profiles ZA1 ZA2 ZAn IA1 IAn Application interface designed using general profile API UDP Topology management, MAC management, routing, discovery protocol, security management Channel access, PAN maintenance, reliable data transport Transmission & reception on the physical radio channel ZigBee NWK IEEE 802.15.4 MAC (CPS) IEEE 802.15.4 PHY IP 802.2 LLC MAC (SSCS) Page 41 Spring 2013 CS 795/895 - Wireless Networked Systems

IEEE 802.15.4 Basics 802.15.4 is a simple packet data protocol for lightweight wireless networks Channel Access is via Carrier Sense Multiple Access with collision avoidance and optional time slotting Message acknowledgement and an optional beacon structure Multi-level security Three bands, 27 channels specified 2.4 GHz: 16 channels, 250 kbps 868.3 MHz : 1 channel, 20 kbps 902-928 MHz: 10 channels, 40 kbps Works well for Long battery life, selectable latency for controllers, sensors, remote monitoring and portable electronics Features of the MAC: Association/dissociation, ACK, frame delivery, channel access mechanism, frame validation, guaranteed time slot management, beacon management, channel scan Page 42 Spring 2013 CS 795/895 - Wireless Networked Systems

IEEE 802.15.4 MAC Overview Employs 64-bit IEEE & 16-bit short addresses Ultimate network size can reach 2 64 nodes (more than we ll probably need ) Using local addressing, simple networks of more than 65,000 (2^16) nodes can be configured, with reduced address overhead Three devices specified Network Coordinator Full Function Device (FFD) Reduced Function Device (RFD) Simple frame structure Reliable delivery of data Association/disassociation AES-128 security CSMA-CA channel access Optional superframe structure with beacons Page 43 Spring 2013 CS 795/895 - Wireless Networked Systems

ZigBee Network Topologies Supports multiple network topologies including Star, Cluster Tree and Mesh Mesh Star Cluster Tree PAN coordinator Full Function Device Reduced Function Device Page 44 Spring 2013 CS 795/895 - Wireless Networked Systems

IEEE 802.15.4 Device Types Three device types Network Coordinator Maintains overall network knowledge; most sophisticated of the three types; most memory and computing power Full Function Device Carries full 802.15.4 functionality and all features specified by the standard Additional memory, computing power make it ideal for a network router function Could also be used in network edge devices (where the network touches the real world) Reduced Function Device Carriers limited (as specified by the standard) functionality to control cost and complexity General usage will be in network edge devices All of these devices can be no more complicated than the transceiver, a simple 8-bit MCU and a pair of AAA batteries! Page 45 Spring 2013 CS 795/895 - Wireless Networked Systems

IEEE 802.15.4 MAC Layer Traffic Type Periodic data (e.g. sensors) Intermittent data (e.g. light switch) Repetitive low latency data (e.g. mouse) Frame Types Data Frame used for all transfers of data Beacon Frame used by a coordinator to transmit beacons Acknowledgment Frame used for confirming successful frame reception MAC Command Frame used for handling all MAC peer entity control transfers Page 46 Spring 2013 CS 795/895 - Wireless Networked Systems

MAC Options Two channel access mechanisms Non-beacon network Standard ALOHA CSMA-CA communications Positive acknowledgement for successfully received packets Beacon-enabled network Superframe structure For dedicated bandwidth and low latency Set up by network coordinator to transmit beacons at predetermined intervals 15ms to 252sec (15.38ms*2n where 0 n 14) 16 equal-width time slots between beacons Channel access in each time slot is contention free Three security levels specified None Access control lists Symmetric key employing AES-128 Page 47 Spring 2013 CS 795/895 - Wireless Networked Systems

PHY frame structure PHY packet fields Preamble (32 bits) synchronization Start of packet delimiter (8 bits) shall be formatted as 11100101 PHY header (8 bits) PSDU length PSDU (0 to 127 bytes) data field Sync Header Start of Preamble Packet Delimiter 4 Octets PHY Header Frame Length (7 bit) 1 Octets 1 Octets Reserve (1 bit) PHY Payload PHY Service Data Unit (PSDU) 0-127 Bytes Page 48 Spring 2013 CS 795/895 - Wireless Networked Systems

ZigBee and Bluetooth Optimized for different applications ZigBee Smaller packets over large network Mostly Static networks with many, infrequently used devices Home automation, toys, remote controls, etc. Bluetooth Larger packets over small network Ad-hoc networks File transfer Screen graphics, pictures, handsfree audio, Mobile phones, headsets, PDAs, etc. Page 49 Spring 2013 CS 795/895 - Wireless Networked Systems

Page 50 Spring 2013 CS 795/895 - Wireless Networked Systems Copyright 2002 The ZigBee and Bluetooth Air interface ZigBee DSSS- 11 chips/ symbol 62.5 K symbols/s 4 Bits/ symbol Peak Information Rate ~128 Kbit/second Bluetooth FHSS 1 M Symbol / second Peak Information Rate ~720 Kbit / second

ZigBee and Bluetooth Protocol Stack Comparison Silicon Application Application Interface Network Layer Data Link Layer MAC Layer MAC Layer PHY Layer ZigBee Stack Zigbee Application Voice Intercom Headset Cordless Group Call Telephony Control Protocol Silicon vcard User Interface vcal vnote OBEX vmessage Dial-up Networking RFCOMM (Serial Port) L2CAP Host Control Interface Link Manager Link Controller Baseband RF Bluetooth Stack Bluetooth Fax Service Discovery Protocol Applications Page 51 Spring 2013 CS 795/895 - Wireless Networked Systems

ZigBee and Bluetooth Timing Considerations ZigBee: Network join time = 30ms typically Sleeping slave changing to active = 15ms typically Active slave channel access time = 15ms typically Bluetooth: Network join time = >3s Sleeping slave changing to active = 3s typically Active slave channel access time = 2ms typically ZigBee protocol is optimized for timing critical applications Page 52 Spring 2013 CS 795/895 - Wireless Networked Systems

ZigBee and Bluetooth Comparison Overview Bluetooth ZigBee AIR INTERFACE FHSS DSSS PROTOCOL STACK 250 kb 28 kb BATTERY rechargeable non-rechargeable DEVICES/NETWORK 8 255 LINK RATE 1 Mbps 250 kbps RANGE ~10 meters (w/o pa) ~30 meters Page 53 Spring 2013 CS 795/895 - Wireless Networked Systems

Wireless Networking Standards Market Name Standard Application Focus System Resources Battery Life (days) Network Size Bandwidth (KB/s) Transmissio n Range (meters) Success Metrics GPRS/GSM 1xRTT/ CDMA Wide Area Voice & Data Wi-Fi 802.11b Web, Email, Video Bluetooth 802.15.1 Cable Replaceme nt 16MB+ 1MB+ 250KB+ 1-7.5-5 1-7 1 32 7 64-128+ ZigBee 802.15.4 Monitoring & Control 4KB - 32KB 100-1,000+ 255 / 65,000 11,000+ 720 20-250 1,000+ 1-100 1-10+ 1-100+ Reach, Quality Speed, Flexibility Cost, Convenien ce Reliability, Power, Cost Page 54 Spring 2013 CS 795/895 - Wireless Networked Systems

Questions Page 55 Spring 2013 CS 795/895 - Wireless Networked Systems