Partial MAC and PHY Proposal for 802.11n

1. Partial MAC and PHY Proposal for 802.11n Joseph Levy, Fatih M. Ozluturk, Eldad ZeiraInterDigital Communications Corporationjoseph.levy@interdigital.com This presentations summarizes the Partial Proposal:11-04-0933-00-000n_Partial_MAC_and_PHY_Proposal.doc J. Levy, et al; InterDigital Communications Corporation

2. Outline • MAC Proposal Highlights • MAC Characteristics • MAC Enhancements • Scheduled Resource Allocation Advantages • Flexible Resource Management • MAC Legacy Support • MAC Simulation Results • PHY Proposal Highlights • PHY Enhancement • MIMO System Overview • PHY Design • SFBC with Eigen-beamforming • PHY Simulation Results Summary • Conclusions J. Levy, et al; InterDigital Communications Corporation

3. MAC Proposal Highlights J. Levy, et al; InterDigital Communications Corporation

4. MAC Features and Advantages • Eliminates hidden node problem • Higher performance for non real time services: • Better stability and fairness towards AP • Higher performance for real time services while guaranteeing QoS: • Reduced STA power consumption and Higher MAC efficiency • Enhanced peer to peer direct transfer of data under control of the AP • Backward compatibility: • With 802.11 MAC - 802.11e - 802.11k • STA and AP • Support of efficient PHY operation • Multiplex of UL and/or DL users • Flexible design efficiently supports: • MIMO, FEC and H–ARQ • OFDMA support • Both 20MHz and 40MHz HT STA in the same superframe J. Levy, et al; InterDigital Communications Corporation

5. Proposed MAC Superframe new addition • Super frame structure with major legacy components: (1) Beacon (2) Contention Free Period (3) Contention Period • Introduced Reservation based allocation (scheduling) • Flexible Management Scheduled Resource Allocation (MSRA) • Scheduled Resource Allocation (SRA) • Open Resource Allocation (ORA) J. Levy, et al; InterDigital Communications Corporation

6. Advantages of Scheduling (SRA) • Significant improvement in battery life • Enables new devices • Efficient data management/processing • Allows simplified Radio Resource management (RRM) • Customization of devices to implement new features • High MAC efficiency for stringent latency, low data rate applications (VoIP, new applications) • Scheduled resource allocations allows for true QoS management J. Levy, et al; InterDigital Communications Corporation

7. Advantages of Flexible Management • Enables efficient NRT allocations • Higher MAC throughput • Eliminates hidden nodes • Common broadcast packet for all the allocation information within super frame (No 802.11 ACKs) • Consistent and predictable MAC operation • Removed 802.11 contention overhead • No Exponential Back off after every attempt • Small Request Packet for Contention in slotted Aloha • Flexible, fair and efficient management of resources • Driven by application and PHY characteristics J. Levy, et al; InterDigital Communications Corporation

8. Proposed MAC Builds on 802.11 • Resource Coordination Function (RCF) • RCF Management Channel Access (RMCA) for small packet transfers and schedule requests/reservations • RCF Scheduled Channel Access (RSCA) for contention free data transfer providing full QoS support J. Levy, et al; InterDigital Communications Corporation

9. MAC Elements Enable Flexibility… • EB (extended beacon) defines: • Higher data rate (then legacy beacon) is possible • The scheduled resource allocation for management (MSRA), user data (SRA) and open RA • MSRA • Slotted Aloha contention for request of BW, association or small data/control packets • Collective Response send after the MSRA period • SRA • Resource Allocated for RT and NRT services • Open RA • Resource (e.g. time) not allocated for MSRA and SRA in the extended Beacon • Used for quick allocations within the super frame or multicast or broadcast traffic. J. Levy, et al; InterDigital Communications Corporation

10. … and Flexibility Supports Multiple PHYs • Supports various PHY implementations • Resource allocations in Time, Frequency, and/or Spatial • 20 and 40 MHz • OFDMA and/or Spatial subchannel allocation J. Levy, et al; InterDigital Communications Corporation

11. Optional messages (3a and 3b) AP 1a 3a 2a 1b 3b 2b STA2 STA1 Extends Peer-to-Peer • Additional messaging enables RRM support at the AP • AP allowed to request teardown of P2P • Messaging for P2P channel characterization before DLP setup J. Levy, et al; InterDigital Communications Corporation

12. New Mac has Full Legacy Support • Legacy station access to the medium is controlled by the MAC • The proposed MAC support all current 802.11/11e MAC processes J. Levy, et al; InterDigital Communications Corporation

13. MAC NRT Simulation Results Summary • Higher stability at medium to high loads obtained at a cost of small and controlled delay • Increase in uplink throughput relative to 802.11e • ~ 15-45 % increase in the number of active users for 0-10% hidden nodes • ~ 30-60 % increase in the average user throughput for 10-30% hidden nodes Note: All the comparisons are against the efficient 802.11e MAC (3 packets per transmit opportunity) J. Levy, et al; InterDigital Communications Corporation

14. Substantially Higher Number of Active Users NRT Uplink Throughput vs. Number of Active Users J. Levy, et al; InterDigital Communications Corporation

15. Stable Delay for High Number of Users Uplink Delay vs. Number of Active Users for NRT J. Levy, et al; InterDigital Communications Corporation

16. Substantial Improvement in Per-User Throughput NRT Uplink Throughput vs. Application Data Rate (8 users) J. Levy, et al; InterDigital Communications Corporation

17. Stable Delay as User Throughput Increases Uplink Delay vs. Application Data Rate (8 users) for NRT J. Levy, et al; InterDigital Communications Corporation

18. MAC Conclusions • Proposed MAC builds on 802.11 and 802.11e • MAC architecture enables • Elimination of hidden nodes • Prolonged battery life • Higher throughput • Radio Resource Management • Support of multiple PHYs • Performance improvements have been demonstrated J. Levy, et al; InterDigital Communications Corporation

19. PHY Proposal Highlights J. Levy, et al; InterDigital Communications Corporation

20. PHY Features and Advantages • Robust performance in all channel conditions, with or without channel state information • Low complexity at both transmitter and receiver • Scalable solution: data rate, throughput • Accommodates any antenna configuration • Flexible PHY that supports both backward compatibility and enhanced MIMO capability • Backward compatible with 802.11a/g • High throughput by leveraging OFDM MIMO J. Levy, et al; InterDigital Communications Corporation

21. Motivation • Maintain backward compatibility while supporting high throughput • Find the best compromise between diversity gain and spatial multiplexing gain • Simplified operational modes • Open loop : Initial acquisition, support of legacy equipment • Closed loop : High throughput capability • Simple scalable architecture J. Levy, et al; InterDigital Communications Corporation

22. Complexity Minimized Through Judicious Use of Diversity and Multiplexing Techniques • Space Frequency Block Coding • Enhances Diversity Gain • Eigen-Beamforming • Enhances multiplexing gain • Channel decomposition • SVD used to diagonalize channel at both Tx and Rcv • Channel Coding • This proposal is compatible with existing channel coding methods (e.g. FEC, interleaving, etc.) • Compatible with other transmitter or receiver elements J. Levy, et al; InterDigital Communications Corporation

23. High Throughput Using Closed Loop Eigen Beamforming Mode (CL-EBM) • Space-frequency coding (SFC) followed by eigen-beamforming (EBM) • Eigen-beamforming is based on Singular Value Decomposition (SVD) decomposition • Eigen-beamforming provides spatial multiplexing (high throughput) at a reasonable complexity • SVD splits the processing between the receiver and the transmitter • Channel is orthogonalized into eigenbeams that assure effective spatial-multiplexing • Does not require complicated receiver processing (no MMSE, SIC, etc) • Relaxed latency and feedback rates due to frequency non-selectivity of eigen-values • SFC provides diversity gain • Robust link maintained with closed loop operation, Channel State Information (CSI) through feedback or reciprocity J. Levy, et al; InterDigital Communications Corporation

24. Open-Loop Spatial Spreading Mode (OL-SSM) • Enables closed loop initiation, transparent support of closed loop operation • Provides legacy support • Space-frequency block code for diversity with a spatial spreading beam forming network Backward Compatibility • OL-SSM can support legacy 802.11a/g STAs or APs • OFDM packet structure compatible with legacy 802.11a/g • Same spectral mask and allocation of subcarriers as the existing 802.11a/g J. Levy, et al; InterDigital Communications Corporation

25. MIMO Block Diagram Transmitter Space Frequency Diversity Beamforming Receiver J. Levy, et al; InterDigital Communications Corporation

26. Power and bit loading is incorporated • Power loading algorithm runs during the closed loop operation using CSI • Eigen-values are ranked per sub-carrier • Eigen-beams are created for each pair of same ranking eigen-values • Alamouti space frequency code applied to each pair • The average SNR per pair of eigen-modes used to create an index into a CQI table J. Levy, et al; InterDigital Communications Corporation

27. Open Loop Spatial Spreading Mode • Spatial spreading supported by reconfiguration of BFN • Antenna beams randomly steered to enhance diversity • Feedback of CSI not required • Legacy support is maintained by removing the SFBC operation J. Levy, et al; InterDigital Communications Corporation

28. PHY Conclusion • Robustness through Space-Frequency Coding • Spatial-multiplexing efficiency through eigen-beamforming • Low implementation complexity is distributed between the transmitter and the receiver • Backward compatible with 802.11a/g • Scalable to various antenna configurations J. Levy, et al; InterDigital Communications Corporation

29. Proposal Conclusions • Partial proposals for backward compatible MAC and PHY • MAC provides high efficiency and stability, reduces battery consumption and eliminates hidden nodes • Scalable PHY provides high throughput and robust performance, with low complexity J. Levy, et al; InterDigital Communications Corporation