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Next Generation Wireless LANs, Second Edition

Book Description

If you've been searching for a way to get up to speed on IEEE 802.11n and 802.11ac WLAN standards without having to wade through the entire specification, then look no further. This comprehensive overview describes the underlying principles, implementation details and key enhancing features of 802.11n and 802.11ac. For many of these features the authors outline the motivation and history behind their adoption into the standard. A detailed discussion of key throughput, robustness, and reliability enhancing features (such as MIMO, multi-user MIMO, 40/80/160 MHz channels, transmit beamforming and packet aggregation) is given, plus clear summaries of issues surrounding legacy interoperability and coexistence. Now updated and significantly revised, this 2nd edition contains new material on 802.11ac throughput, including revised chapters on MAC and interoperability, plus new chapters on 802.11ac PHY and multi-user MIMO. An ideal reference for designers of WLAN equipment, network managers, and researchers in the field of wireless communications.

Table of Contents

  1. Coverpage
  2. Next Generation Wireless LANs
  3. Title page
  4. Copyright page
  5. Dedication
  6. Contents
  7. Foreword by Dr. Andrew Myles
  8. Preface to the first edition
  9. Preface to the second edition
  10. List of abbreviations
  11. Chapter 1 Introduction
    1. 1.1 An overview of IEEE 802.11
      1. 1.1.1 The 802.11 MAC
      2. 1.1.2 The 802.11 PHYs
      3. 1.1.3 The 802.11 network architecture
      4. 1.1.4 Wi-Fi Direct
    2. 1.2 History of high throughput and 802.11n
      1. 1.2.1 The High Throughput Study Group
      2. 1.2.2 Formation of the High Throughput Task Group (TGn)
      3. 1.2.3 Call for proposals
      4. 1.2.4 Handheld devices
      5. 1.2.5 Merging of proposals
      6. 1.2.6 802.11n amendment drafts
    3. 1.3 Environments and applications for 802.11n
    4. 1.4 Major features of 802.11n
    5. 1.5 History of Very High Throughput and 802.11ac
    6. 1.6 Outline of chapters
    7. References
  12. Part I Physical layer
    1. Chapter 2 Orthogonal frequency division multiplexing
      1. 2.1 Background
      2. 2.2 Comparison to single carrier modulation
      3. References
    2. Chapter 3 MIMO/SDM basics
      1. 3.1 SISO (802.11a/g) background
      2. 3.2 MIMO basics
      3. 3.3 SDM basics
      4. 3.4 MIMO environment
      5. 3.5 802.11n and 802.11ac propagation model
        1. 3.5.1 Impulse response
        2. 3.5.2 Antenna correlation
        3. 3.5.3 802.11n Doppler model
        4. 3.5.4 802.11ac Doppler model
        5. 3.5.5 Physical layer impairments
        6. 3.5.6 Path loss
      6. 3.6 Linear receiver design
      7. 3.7 Maximum likelihood estimation
      8. References
      9. Appendix 3.1 802.11n channel models
    3. Chapter 4 PHY interoperability with 11a/g legacy OFDM devices
      1. 4.1 11a packet structure review
        1. 4.1.1 Short Training field
        2. 4.1.2 Long Training field
        3. 4.1.3 Signal field
        4. 4.1.4 Data field
        5. 4.1.5 Packet encoding process
        6. 4.1.6 Receive procedure
      2. 4.2 Mixed format high throughput packet structure
        1. 4.2.1 Non-HT portion of the MF preamble
        2. 4.2.2 HT portion of the MF preamble
        3. 4.2.3 Data field
        4. 4.2.4 HT MF receive procedure
      3. References
      4. Appendix 4.1 20 MHz basic MCS tables
    4. Chapter 5 High throughput
      1. 5.1 40 MHz channel
        1. 5.1.1 40 MHz subcarrier design and spectral mask
        2. 5.1.2 40 MHz channel design
        3. 5.1.3 40 MHz mixed format preamble
        4. 5.1.4 40 MHz data encoding
        5. 5.1.5 MCS 32: high throughput duplicate format
        6. 5.1.6 20/40 MHz coexistence with legacy in the PHY
        7. 5.1.7 Performance improvement with 40 MHz
      2. 5.2 20 MHz enhancements: additional data subcarriers
      3. 5.3 MCS enhancements: spatial streams and code rate
      4. 5.4 Greenfield (GF) preamble
        1. 5.4.1 Format of the GF preamble
        2. 5.4.2 PHY efficiency
        3. 5.4.3 Issues with GF
        4. 5.4.4 Preamble auto-detection
      5. 5.5 Short guard interval
      6. References
      7. Appendix 5.1 Channel allocation
      8. Appendix 5.2 40 MHz basic MCS tables
      9. Appendix 5.3 Physical layer waveform parameters
    5. Chapter 6 Robust performance
      1. 6.1 Receive diversity
        1. 6.1.1 Maximal ratio combining basics
        2. 6.1.2 MIMO performance improvement with receive diversity
        3. 6.1.3 Selection diversity
      2. 6.2 Spatial expansion
      3. 6.3 Space-time block coding
        1. 6.3.1 Alamouti scheme background
        2. 6.3.2 Additional STBC antenna configurations
        3. 6.3.3 STBC receiver and equalization
        4. 6.3.4 Transmission and packet encoding process with STBC
      4. 6.4 Low density parity check codes
        1. 6.4.1 LDPC encoding process
        2. 6.4.2 Effective code rate
        3. 6.4.3 LDPC coding gain
      5. References
      6. Appendix 6.1 Parity check matrices
    6. Chapter 7 Very High Throughput PHY
      1. 7.1 Channelization
      2. 7.2 Single user (SU) VHT packet structure
      3. 7.3 VHT format preamble
        1. 7.3.1 Non-VHT portion of the VHT format preamble
        2. 7.3.2 VHT portion of the VHT format preamble
        3. 7.3.3 VHT data field
      4. 7.4 Modulation coding scheme
      5. References
  13. Part II Medium access control layer
    1. Chapter 8 Medium access control
      1. 8.1 Protocol layering
      2. 8.2 Finding, joining, and leaving a BSS
        1. 8.2.1 Beacons
        2. 8.2.2 Scanning
        3. 8.2.3 Authentication
        4. 8.2.4 Association
        5. 8.2.5 Reassociation
        6. 8.2.6 Disassociation
        7. 8.2.7 802.1X Authentication
        8. 8.2.8 Key distribution
      3. 8.3 Distributed channel access
        1. 8.3.1 Basic channel access timing
      4. 8.4 Data/ACK frame exchange
        1. 8.4.1 Fragmentation
        2. 8.4.2 Duplicate detection
        3. 8.4.3 Data/ACK sequence overhead and fairness
      5. 8.5 Hidden node problem
        1. 8.5.1 Network allocation vector (NAV)
        2. 8.5.2 EIFS
      6. 8.6 Enhanced distributed channel access
        1. 8.6.1 Transmit opportunity
        2. 8.6.2 Channel access timing with EDCA
        3. 8.6.3 EDCA access parameters
        4. 8.6.4 EIFS revisited
        5. 8.6.5 Collision detect
        6. 8.6.6 QoS Data frame
      7. 8.7 Block acknowledgement
        1. 8.7.1 Block data frame exchange
      8. 8.8 Power management
        1. 8.8.1 AP TIM transmissions
        2. 8.8.2 PS mode operation
        3. 8.8.3 WNM-Sleep
        4. 8.8.4 SM power save
        5. 8.8.5 Operating Mode Notification
      9. References
    2. Chapter 9 MAC throughput enhancements
      1. 9.1 Reasons for change
        1. 9.1.1 Throughput without MAC changes
        2. 9.1.2 MAC throughput enhancements
        3. 9.1.3 Throughput with MAC efficiency enhancements
      2. 9.2 Aggregation
        1. 9.2.1 Aggregate MSDU (A-MSDU)
        2. 9.2.2 Aggregate MPDU (A-MPDU)
        3. 9.2.3 Aggregate PSDU (A-PSDU)
        4. 9.2.4 A-MPDU in VHT PPDUs
        5. 9.2.5 VHT single MPDU
      3. 9.3 Block acknowledgement
        1. 9.3.1 Immediate and delayed block ack
        2. 9.3.2 Block ack session initiation
        3. 9.3.3 Block ack session data transfer
        4. 9.3.4 Block ack session tear down
        5. 9.3.5 Normal ack policy in a non-aggregate
        6. 9.3.6 Reorder buffer operation
      4. 9.4 HT-immediate block ack
        1. 9.4.1 Normal Ack policy in an aggregate
        2. 9.4.2 Compressed block ack
        3. 9.4.3 Full state and partial state block ack
        4. 9.4.4 HT-immediate block ack TXOP sequences
      5. 9.5 HT-delayed block ack
        1. 9.5.1 HT-delayed block ack TXOP sequences
      6. References
    3. Chapter 10 Advanced channel access techniques
      1. 10.1 PCF
        1. 10.1.1 Establishing the CFP
        2. 10.1.2 NAV during the CFP
        3. 10.1.3 Data transfer during the CFP
        4. 10.1.4 PCF limitations
      2. 10.2 HCCA
        1. 10.2.1 Traffic streams
        2. 10.2.2 Controlled access phases
        3. 10.2.3 Polled TXOP
        4. 10.2.4 TXOP requests
        5. 10.2.5 Use of RTS/CTS
        6. 10.2.6 HCCA limitations
      3. 10.3 Reverse direction protocol
        1. 10.3.1 Reverse direction frame exchange
        2. 10.3.2 Reverse direction rules
        3. 10.3.3 Error recovery
      4. 10.4 PSMP
        1. 10.4.1 PSMP recovery
        2. 10.4.2 PSMP burst
        3. 10.4.3 Resource allocation
        4. 10.4.4 Block ack usage under PSMP
      5. References
    4. Chapter 11 Interoperability and coexistence
      1. 11.1 Station capabilities and operation
        1. 11.1.1 HT station PHY capabilities
        2. 11.1.2 VHT station PHY capabilities
        3. 11.1.3 HT station MAC capabilities
        4. 11.1.4 VHT station MAC capabilities
        5. 11.1.5 Advanced capabilities
      2. 11.2 BSS operation
        1. 11.2.1 Beacon transmission
        2. 11.2.2 20 MHz BSS operation
        3. 11.2.3 20/40 MHz HT BSS operation
        4. 11.2.4 VHT BSS operation
        5. 11.2.5 OBSS scanning requirements
        6. 11.2.6 Signaling 40 MHz intolerance
        7. 11.2.7 Channel management at the AP
        8. 11.2.8 Establishing a VHT BSS in the 5 GHz band
      3. 11.3 A summary of fields controlling 40 MHz operation
      4. 11.4 Channel access in wider channels
        1. 11.4.1 Overlapping BSSs
        2. 11.4.2 Wide channel access using RTS/CTS
        3. 11.4.3 TXOP rules for wide channel access
        4. 11.4.4 Clear channel assessment
        5. 11.4.5 NAV assertion in an HT and VHT BSS
      5. 11.5 Protection
        1. 11.5.1 Protection with 802.11b stations present
        2. 11.5.2 Protection with 802.11g or 802.11a stations present
        3. 11.5.3 Protection for OBSS legacy stations
        4. 11.5.4 RIFS burst protection
        5. 11.5.5 HT Greenfield format protection
        6. 11.5.6 RTS/CTS protection
        7. 11.5.7 CTS-to-Self protection
        8. 11.5.8 Protection using a non-HT, HT mixed, or VHT PPDU with non-HT response
        9. 11.5.9 Non-HT station deferral with HT mixed and VHT format PPDUs
        10. 11.5.10 L-SIG TXOP protection
      6. 11.6 Phased coexistence operation (PCO)
        1. 11.6.1 Basic operation
        2. 11.6.2 Minimizing real-time disruption
      7. References
    5. Chapter 12 MAC frame formats
      1. 12.1 General frame format
        1. 12.1.1 Frame Control field
        2. 12.1.2 Duration/ID field
        3. 12.1.3 Address fields
        4. 12.1.4 Sequence Control field
        5. 12.1.5 QoS Control field
        6. 12.1.6 HT Control field
        7. 12.1.7 Frame Body field
        8. 12.1.8 FCS field
      2. 12.2 Format of individual frame types
        1. 12.2.1 Control frames
        2. 12.2.2 Data frames
        3. 12.2.3 Management frames
      3. 12.3 Management frame fields
        1. 12.3.1 Fields that are not information elements
        2. 12.3.2 Information elements
      4. References
  14. Part III Transmit beamforming, multi-user MIMO, and fast link adaptation
    1. Chapter 13 Transmit beamforming
      1. 13.1 Singular value decomposition
      2. 13.2 Transmit beamforming with SVD
      3. 13.3 Eigenvalue analysis
      4. 13.4 Unequal MCS
      5. 13.5 Receiver design
      6. 13.6 Channel sounding
      7. 13.7 Channel state information feedback
        1. 13.7.1 Implicit feedback
        2. 13.7.2 Explicit feedback
      8. 13.8 Improved performance with transmit beamforming
      9. 13.9 Degradations
      10. 13.10 MAC considerations
        1. 13.10.1 Sounding PPDUs
        2. 13.10.2 Implicit feedback beamforming
        3. 13.10.3 Explicit feedback beamforming
      11. 13.11 Comparison between implicit and explicit
      12. 13.12 Transmit beamforming in 802.11ac
        1. 13.12.1 VHT sounding protocol
      13. References
      14. Appendix 13.1 Unequal MCS for 802.11n
        1. Unequal MCS for 20 MHz
        2. Unequal MCS for 40 MHz
    2. Chapter 14 Multi-user MIMO
      1. 14.1 MU-MIMO pre-coding
      2. 14.2 Receiver design
      3. 14.3 PHY considerations
        1. 14.3.1 VHT MU preamble
        2. 14.3.2 VHT MU data field
        3. 14.3.3 Compressed beamforming matrices
      4. 14.4 Group ID
        1. 14.4.1 Receive operation
        2. 14.4.2 Group ID management
      5. 14.5 MAC support for MU-MIMO
        1. 14.5.1 MU aggregation
        2. 14.5.2 MU acknowledgements
        3. 14.5.3 EDCA TXOPs for MU sequences
        4. 14.5.4 TXOP sharing
      6. 14.6 VHT sounding protocol for MU-MIMO
        1. 14.6.1 The basic sounding exchange
        2. 14.6.2 Support for fragmentation
      7. References
    3. Chapter 15 Fast link adaption
      1. 15.1 MCS feedback
      2. 15.2 MCS feedback mechanisms
      3. 15.3 MCS feedback using the HT variant HT Control field
      4. 15.4 MCS feedback using the VHT variant HT Control field
  15. Index