A Guide. Wireless Network Library Bluetooth

Transcription

1 A Guide to the Wireless Network Library Conforming to Standard v1.1

2 SystemView by ELANIX Copyright , Eagleware Corporation All rights reserved. Eagleware-Elanix Corporation 3585 Engineering Drive, Suite 150 Norcross, GA USA Phone: +1 (678) , Fax: +1 (678) Support Web: Unpublished work. All rights reserved under the U.S. Copyright Act. Restricted Rights Apply. This document may not, in whole or in part, be copied, photocopied, reproduced, translated, or reduced to any electronic medium or machine-readable form without the prior written consent of Eagleware Corporation. This document and the associated software are proprietary to Eagleware Corporation. SystemView by ELANIX, and ELANIX are registered trademarks of Eagleware Corporation. MetaSystem is a trademark of Eagleware Corporation. Windows is a trademark of Microsoft Corporation. Other trademarks or registered trademarks used in this document are the property of their respective owners. Document created by Elanix, Inc and: Ryan Menezes Manoj Ananthapadmanabhan Electrical and Computer Engineering University of Wisconsin-Madison Document Number SVU-BLU1001 Printed in the United States of America. ii

3 Table of Contents INTRODUCTION... V TRANSMITTER...1 TRANS...1 RECEIVER...7 RECV...7 BLUETOOTH CLOCK...9 CLOCK_N...9 FREQUENCY HOP SELECTOR...10 FH...10 ACCESS CODE CORRELATOR...12 ACC_CORR /3 FEC ENCODER...13 R1/3 E /3 FEC DECODER...14 R1/3 D /3 FEC ENCODER...15 R2/3E /3 FEC DECODER...16 R2/3D...16 HEC ENCODER...17 HEC_ENC...17 HEC DECODER...18 HEC_DEC...18 CRC ENCODER...19 CRC_ENC...19 CRC DECODER...20 CRC_DEC...20 DATA WHITENER...21 WHITENER...21 iii

4 LIST OF ACRONYMS AM_ADDR ARQ BD_ADDR CAC CRC DAC DIAC DV FEC FH FHS GIAC HEC HV IAC ISM L_CH L2CAP LAP NAP PM_ADDR SAP SAR SEQN TDD UAP Active Member Address Automatic Repeat request Device Address Channel Access Code Cyclic Redundancy Check Device Access Code Dedicated Inquiry Access Code Data Voice Forward Error Correction code Frequency Hopping Frequency Hop Synchronization General Inquiry Access Code Header-Error-Check High-quality Voice Inquiry Access Code Industrial, Scientific, Medical Logical Channel Logical Link Control & Adaption Protocol Lower Address Part Non-significant Address Part Parked Member Address Service Access Points Segmentation and Reassembly Sequential Numbering Scheme Time-Division Duplex Upper Address Part iv

5 Introduction is a Wireless Personal Area Network (WPAN) protocol designed as a cable-replacement technology - low cost, modest speed, and short range (<10 meters). It operates in the 2.4GHz ISM band and facilitates ad-hoc connections for stationary and mobile communication environments. makes a clear distinction between voice and data communications. Voice packets can be transmitted with less overhead and limited reliability while data packets are transmitted with high reliability and have error detecting/correcting mechanisms. The physical (or PHY) layer uses the frequency-hopping spread spectrum (FHSS) technique. Spectrum spreading is accomplished by frequency hopping, with 79 hops spaced by 1 MHz, between GHz and GHz. hops at a rate of 1600 hops/sec. It uses Gaussian frequency shift keying (GFSK) modulation with modulation index 0.28 to 0.35 i.e. frequency deviation of 140KHz to 175KHz. The channel is divided into time slots, each 625 µsecs in length where each slot corresponds to an RF hop frequency. thus uses frequency hopping and Time Division Duplex scheme to combat interference and fading for full duplex transmissions. Owing to tradeoff between hardware complexity and receiver performance the existing system does not use channel distortion compensation uses Forward Error Correction (FEC) with 2/3 shortened Hamming code and rate 1/3 bit repeat. A low-power radio interface was chosen, operating on the globally available 2.45 GHz band. The radio air interface features nominal antenna power of 0 dbm and complies with FCC rules for the ISM band, and the nominal radio link range is upto 10 meters, although range can be extended up to 100 meters by increasing the transmission power to 20dBm. can support a maximum of three synchronous-connectionoriented (SCO) links. SCO links are voice-oriented and designed to v

6 support real-time, isochronous applications such as cordless telephony or headsets. also supports asynchronous connection links (ACLs) used to exchange data in non-time-critical applications. Each voice channel supports a 64Kbps synchronous channel in each direction. The maximum user rate that can be obtained over asynchronous link is Kbps and a return link of 57.6 Kbps is supported. system supports both point-to-point connections and point-tomultipoint connections. In point-to-multipoint connection, the channel is shared among several devices. Two or more devices sharing the same channel form a piconet. There is one master device and up to seven active slave devices in a piconet. These devices can be in any of the states: active, sniff, hold and park. The latter three are low-power states with park being the lowest power state. Multiple piconets with overlapping coverage areas form a scatternet. vi

7 Token Name: Abbreviation: Transmitter Trans Synopsis: The Transmitter block performs the following functions Error Correcting and detecting at rate 1/3. Error Correcting and detecting at rate 2/3. Encodes a 10 bit block from a serial bit stream into 15 bits for each input block LSB first. Encoding scheme is a (15, 10) shortened Hamming code. Error Checking using CRC by appending parity bits to output. Error Checking is performed on all packet headers and ACL payloads to validate integrity of received data. (Scrambling) mixing a PN sequence with data to reduce dc bias. Access Code Generator generates the access code that is placed at the beginning of a packet. The access code is either 68 or 72 bits long. It is used for synchronization, identification, paging and inquiry procedures The packet Header consists of 10 bits before HEC. The packet is then passed through a 1/3 FEC to get 54 bits Multiplexes the access code, header and payload to generate the packet Specification References: Part B 5.1, 5.2, 4.3, 5.4, 7, 4.2, 13.2, 4.5, 4.4 See Also: Receiver Parameters: Parameter Symbol Definition LAP 24 bit Lower Address Part of device address UAP 8 bit Upper Address Part of device address NAP 16 bit Non-significant Part of device address State master/slave State of operation Hop System 23/79 hop system Pkt Type Packet Type AM_ADDR 3 bit Active member address

8 Flow ARQN SEQN Payload Length L_CH Flow (L2CAP) SR SP Device Class Scan Mode Page Substate Bit specifying flow Bit specifying Automatic Repeat Request Bit specifying Sequence Number Payload length Logical Channel Flow at L2CAP layer 2 bit Scan Repetition field 2 bit Scan Period field 24 bit device class 3 bit field indicating page scan mode A or B Train Token Inputs: Clock N. Token Outputs: Packet Header Payload Discussion: HEC The generator polynomial is D8+D7+D5+D2+D+1. For each block, the initial state of the generator is taken from the UAP/DCI parameter. The D7 position for the UAP/DCI is weighted at 128; D6 is half that and so on. CRC encodes bits of information by appending 16 parity bits to output. CRC The generator polynomial is D16+D12+D5+1. For each block, the initial state of the generator is taken from the UAP/DCI parameter. The D7 position for the UAP/DCI is weighted at 128; D6 is half that and so on. Whitener data whitener uses polynomial D7+D4+1. Initial value for bits 0-5 of the generator comes from bits 1-6 of the input CLK arriving at the first input bit with bit 6 of the generator set to 1. Access Code Generator If Packet Header follows, length is 72 bits, otherwise access code is 68 bits long. The CAC is 72 bits long. DAC, GIAC and DIAC are 72 bits long if used in conjunction with FHS packets, otherwise they are of length 68 bits. 2

9 Pseudo random noise (PN) sequence is generated using 1 + D + D 3 + D 4 + D 6 Structure of Access Code (68/72) Preamble(4) Sync Word(64) Trailer (4) Preamble-to detect the edges of received data, either 0101 or 1010 depending on 1 st bit of sync word being 0 or 1 Sync Word- formed from LAP using a predefined algorithm. Receiver does 64 point correlation with sync word Trailer- If a payload is following, the trailer is similar to preamble. If last bit of Sync word is 0 it is 1010 else 0101 Structure of Sync Word (64) BCH Parity(34) LAP(24) Barker(6) BCH Parity Word- has key part of sync word LAP-lower address part of 48 bit device MAC address Barker- 6 bits attached to make the last 7 bits a Barker code Header Structure of Header (18*3=54) AM_ADDR(3) Pkt Type(4) Flow(1) ARQN (1) SEQN(1) HEC(8) AM_ADDR active member address of upto 7 active slaves Packet Type- SCO,ACL,NULL or POLL and type of error correction for payload, number of slots for payload Flow- flag indicating device unable to receive data due to buffer field ARQN-for ARQ scheme SEQN- toggled each time a new packet is sent. Remains unchanged for retransmissions so that receiver can differentiate between packet copies HEC- CRC function performed on header and represented by a Generator Polynomial 647 in Octal. Initialized by Master or Slave UAP or DCI (Default Check Initialization= all zeros). If HEC fails, rest of Packet is ignored 3

10 Packet Types Supported Segment Packet Type Code No of Slots covered SCO link ACL link Payload Header (bytes) User Payload (bytes) FEC CRC or 2 ID 0 0 No No Control NULL No No No No Packets POLL No No No No FHS No 18 2/3 No Single Slot data packets 3 slot data packets DM /3 Yes DH No Yes HV1 - No 10 1/3 No HV2 - No 20 2/3 No HV3 - No 30 No No DV - (1) 10(0-9) (2/3) (Yes) AUX No No DM /3 Yes DH No Yes slot data DM /3 Yes packets DH No Yes Payload Generator Input/ Parameters: Packet Type,Data, PN Sequence for whitening, information bits ACL Packets Structure of ACL Payload (0-2774) Payload Header(8/16) Data(0-2712) CRC(16) 4

11 Payload Header SCO Packets Payload(240) Structure of ACL Payload Header (8/16) L_CH(3) Flow(1) Length(8) undefined(4) L_CH (Logical Channel field) indicates whether this packet is start or continuation of an L2CAPmessage (several ACL packets) or an LMP message Flow- controls data transfer at L2CAP level Length- length of payload in bytes Same access code as ACL, no ARQ,CRC and SEQ Fixed payload 30 bytes=240 bits representing source data of 10,20 or 30 bytes depending on FEC rate Mixed SCO/ACL (DV Packet) Voice Payload(80) Structure of DV packet (0-) Payload Data Header(8) Payload(0-72) Data CRC(16) Pad(4) DV Packets are special SCO packets. Voice field is HV1 10byte and not protected. Data field is protected by 2/3 rate FEC. Retransmission of data field is possible Special Packets ID only access code, used in pre-connection NUL access code + pkt header, used for ARQ POLL same structure as NULL, but has to be acknowledged FHS Frequency Hop synchronization Packet. Sent during enquiry process,page procedure and when a master takes over. It provides all information required by recipient to address sender in terms of timing, device address code 5

12 BCH Parity (34) LAP (24) Undef (2) SR (2) SP (2) Structure of FHS packet (0-) UAP NAP Class (2) (2) (16) AM_ADDR (3) CLK[27:2] (26) Page Mode (3) BCH Parity Word- has key part of sync word LAP-lower address part of 48 bit device MAC address UAP - upper address part of 48 bit device MAC address NAP-non significant address part of 48 bit device MAC address SR- page scan repetition SP- page scan period Page Mode-senders default page mode Class- class of device e.g printer, PDA,cell phone AM_ADDR- for slave if being sent by master. Equals 0 for enquiry scan CLK- native clock of sender Structure of Packet ( ) Access code(68/72) header(54) payload(0-2745) Header- control information associated with packet and link Payload- message information Example: bt_trn.svu 6

13 Token Name: Abbreviation: Receiver Recv Synopsis: The Receiver block does the following functions Error Correcting and detecting at rate 1/3. Decodes a 3 bit block from a serial soft bit stream by averaging the 3 input bits, then comparing the average with the threshold to output 1 hard bit Error Correcting and detecting at rate 2/3. Decodes a 15 bit block from a serial bit stream with lsb in first and serially outputs 10 bits for each input block. An error flag is output for each block indicating 2 or more errors were detected. FEC scheme is a (15, 10) shortened Hamming code. Error Checking by decoding 18 bits of header message and parity bits Decodes bits of header message and parity bits. (Unscrambling) Demultiplexes the packet Specification References: Part B 5.1, 5.2, 4.3.6, 5.4, 4.2 See Also: Transmitter Parameters: Parameter Symbol Definition Logic 0 Output value representing logical 0 Logic 1 Output value representing logical 1 Threshold The value that separates a logical 1 from a logical 0 State master/slave State of operation of device FEC decode soft/hard Whether soft or hard decoding is used for the 2/3 hamming code UapDci Upper Address Part or Default Check Initialization Payload Len Length of payload Hop System 23/79 Hop system KOffset Either 8 or 24 depending on control word. 7

14 Token Inputs: Clock N Encoded bit stream from Access code correlator Access code flag Token Outputs: Header Error flag (HEC) Payload Error flag (CRC) Discussion: HEC The generator polynomial is D8+D7+D5+D2+D+1. For each block, the initial state of the generator is taken from the UAP/DCI parameter. The D7 position for the UAP/DCI is weighted at 128, D6 is half that and so on. CRC decodes bits of header message and parity bits. The generator polynomial is D16+D12+D5+1. For each block, the initial state of the generator is taken from the UAP/DCI parameter. The D7 position for the UAP/DCI is weighted at 128, D6 is half that and so on. Whitener data whitener uses polynomial D7+D4+1. Initial value for bits 0-5 of the generator comes from bits 1-6 of the input CLK arriving at the first input bit with bit 6 of the generator set to 1. Example: bt.svu 8

15 Token Name: Abbreviation: Clock Clock_N Synopsis: native clock (counter) is nominally driven by a 3200 Hz pulse train. This clock runs open loop and is never adjusted. Specification References: Part B 10.3 See Also: Frequency Hop Generator Parameters: Parameter Symbol Definition Threshold The value that separates a logical 1 from a logical 0 CLK Offset Offset from base clock Token Inputs: Pulse train at 3200Hz Token Outputs: CLKN CLK0 CLK1 CLK2 CLK12 Discussion: Example: bt_clock.svu 9

16 Token Name: Abbreviation: Frequency Hop Selector fh Synopsis: frequency hop generator. Specification References: Part B 11 See Also: Clock Parameters: Parameter Symbol Definition Hop System 79/23 hop systems State Page/Inquiry; Page Scan/Inquiry Scan; Master Page Response; Slave Page Response; Connection UAP/LAP Upper Address Part consists of an 8 bit field whereas Lower Address part is a 24 bit field of the device address. K Offset Either 8 or 24 depending on control word. Token Inputs: Clock Token Outputs: X A Add1 B XOR1 C Y1 XOR2 D PERM5 E F Y2 ADDR2 FHop 10

17 Discussion: Substates determine hopping sequence 1. Page scan 32 unique frequencies, period length = Page response 32 frequencies, one-one correspondence with page scan 3. Inquiry scan 32 unique frequencies, period length = Inquiry response 32 frequencies, one-one correspondence with page scan 5. Connection 79 frequencies, very long period length Example: bt_fh.svu 11

18 Token Name: Abbreviation: Access Code Correlator ACC_Corr Synopsis: Access code correlator Specification References: Part B 4.2 See Also: Parameters: Parameter Symbol Definition Threshold The value that separates a logical 1 from a logical 0 LAP 24 bit lower address part of device address Access code size Size of code 68/72 depending on packet type/ Logic1 Output value representing logical 1 Logic0 Output value representing logical 0 Acc Code threshold Threshold for firing of Access code correlator in number of bits < 64. Token Inputs: Demodulated Signal -Packet Token Outputs: Packet Access code flag Discussion: Performs a sliding correlation of an input signal with an oversampled sequence and outputs a 1 on the control bit if the threshold is crossed. If the number of errors in correlation is below the threshold, the packet is assumed intended/addressed for this device. Example: bt_acc_corr.svu 12

19 Token Name: Abbreviation: 1/3 FEC Encoder R1/3 E Synopsis: Error Correcting and detecting. Rate 1/3 -(repetition thrice). Encodes 1 bit by copying itself three times Specification References: Part B 5.1 See Also: 1/3 FEC Decoder Parameters: Parameter Symbol Definition Logic 0 (v) Output logic zero Logic 1 (v) Output logic one Threshold (v) Input logic threshold level Token Inputs: Bit stream Token Outputs: Encoded bit stream Discussion: Example: bt_r1o3.svu 13

20 Token Name: Abbreviation: 1/3 FEC Decoder R1/3 D Synopsis: Error Correcting and detecting. Rate 1/3 -(repetition thrice). Decodes a 3 bit block from a serial soft bit stream by averaging the 3 input bits, then comparing the average with the threshold to output 1 hard bit. Specification References: Part B 5.1 See Also: 1/3 FEC Encoder Parameters: Parameter Symbol Definition Logic 0(v) Output logic zero Logic 1(v) Output logic one Threshold (v) Input logic threshold level Soft(0/1) Token Inputs: Bit stream Token Outputs: Decoded bit stream Discussion: Example: bt_r1o3.svu 14

21 Token Name: Abbreviation: 2/3 FEC Encoder R2/3E Synopsis: The token encodes a 10 bit block from a serial bit stream with LSB in first and serially outputs 15 bits for each input block. LSB is output first. Error correcting scheme is a (15,10) shortened Hamming code. Specification References: Part B 5.2 See Also: 2/3 FEC Decoder Parameters: Parameter Symbol Definition Logic 0(v) Output logic zero Logic 1(v) Output logic one Threshold (v) Input logic threshold level Token Inputs: Bit stream Token Outputs: Encoded bit stream Discussion: Example: bt_r2o3.svu 15

22 Token Name: Abbreviation: 2/3 FEC Decoder R2/3D Synopsis: This token decodes a 15 bit block from a serial bit stream with LSB in first and serially outputs 10 bits for each input block LSB first on output 0. An error flag is output for each block on output 1 indicating 2 or more errors were detected. FEC scheme is a (15,10) shortened Hamming code. Specification References: Part B 5.2 See Also: 2/3 FEC Encoder Parameters: Parameter Symbol Definition Logic 0(v) Output logic zero Logic 1(v) Output logic one Threshold (v) Input logic threshold level Token Inputs: Bit stream Token Outputs: Decoded bit stream Discussion: Example: bt_r2o3.svu 16

23 Token Name: Abbreviation: HEC Encoder HEC_Enc Synopsis: Error Checking. Encodes 10 bits of header information by appending 8 parity bits to output Specification References: Part B 4.3.6, 5.4 See Also: HEC Decoder Parameters: Parameter Symbol Definition Logic 0(v) Output logic zero Logic 1(v) Output logic one Threshold (v) Input logic threshold level UAP/DCI(0-255) Token Inputs: Bit stream Token Outputs: Encoded bit stream Discussion: The generator polynomial is D8+D7+D5+D2+D+1. For each block, the initial state of the generator is taken from the UAP/DCI parameter. The D7 position for the UAP/DCI is weighted at 128, D6 is half that and so on. Example: bt_hec.svu 17

24 Token Name: Abbreviation: HEC Decoder HEC_Dec Synopsis: Error Checking. Decodes 18 bits of header message and parity bits Specification References: Part B 4.3.6, 5.4 See Also: HEC Encoder Parameters: Parameter Symbol Definition Logic 0(v) Output logic zero Logic 1(v) Output logic one Threshold (v) Input logic threshold level UAP/DCI(0-255) Token Inputs: Bit stream Token Outputs: Decoded bit stream Discussion: The generator polynomial is D8+D7+D5+D2+D+1. For each block, the initial state of the generator is taken from the UAP/DCI parameter. The D7 position for the UAP/DCI is weighted at 128, D6 is half that and so on. Example: bt_hec.svu 18

25 Token Name: Abbreviation: CRC Encoder CRC_Enc Synopsis: Error Checking performed on all packet headers and ACL payloads to validate integrity of received data. Specification References: Part B 5.4 See Also: CRC Decoder Parameters: Parameter Symbol Definition Logic 0(v) Output logic zero Logic 1(v) Output logic one Threshold (v) Input logic threshold level UAP/DCI(0-255) Token Inputs: Bit stream Token Outputs: Encoded bit stream Discussion: Encodes bits of information by appending 16 parity bits to output. The generator polynomial is D16+D12+D5+1. For each block, the initial state of the generator is taken from the UAP/DCI parameter. The D7 position for the UAP/DCI is weighted at 128, D6 is half that and so on. Example: bt_crc.svu 19

26 Token Name: Abbreviation: CRC Decoder CRC_Dec Synopsis: Decodes bits of header message and parity bits. Specification References: Part B 5.4 See Also: CRC Encoder Parameters: Parameter Symbol Definition Logic 0(v) Output logic zero Logic 1(v) Output logic one Threshold (v) Input logic threshold level UAP/DCI(0-255) Token Inputs: Bit stream Token Outputs: Encoded bit stream Discussion: Decodes bits of header message and parity bits. The generator polynomial is D16+D12+D5+1. For each block, the initial state of the generator is taken from the UAP/DCI parameter. The D7 position for the UAP/DCI is weighted at 128, D6 is half that and so on. Example: bt_crc.svu 20

27 Token Name: Abbreviation: Data Whitener Whitener Synopsis: (Scrambling) mixing a PN sequence with data to reduce dc bias Specification References: Part B 7 See Also: Parameters: Parameter Symbol Definition Logic 0(v) Output logic zero Logic 1(v) Output logic one Threshold (v) Input logic threshold level Token Inputs: Bit stream Token Outputs: Whitened bit stream Discussion: data whitener uses polynomial D7+D4+1. Initial value for bits 0-5 of the generator comes from bits 1-6 of the input CLK arriving at the first input bit with bit 6 of the generator set to 1. Example: bt_whitener.svu 21

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