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SP Spatial Sharing among BSSs: Resolution to CID 143

SP Spatial Sharing among BSSs: Resolution to CID 143. Date: 20 14-8-28. Abstract.

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SP Spatial Sharing among BSSs: Resolution to CID 143

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  1. SP Spatial Sharing among BSSs: Resolution to CID 143 Date: 2014-8-28 Wei Feng, Tsinghua University

  2. Abstract • This is a submission for comment resolution on D0.01 for comment #143. This submission provides a MAC mechanism to support SP spatial sharing between multiple co-channel BSSs. The mechanism offers an option to further enhance system throughput. Wei Feng, Tsinghua University

  3. Comment #143 • A PCP can only obtain information on how other PBSSs in the same cluster interfere with links in itself. However, it can not take action to avoid itself interfering others. In addition, no specific instruction of when to start interference measurement or spatial sharing process is depicted. • Resolution: Mechanism for reporting interference from and to a PBSS within a cluster should be illustrated. Wei Feng, Tsinghua University

  4. Co-Channel Interference • Interference between the same standard In both IEEE 802.11ad and IEEE 802.11aj, 60-GHz channel is divided into 4 bands. Co-channel interference between BSSs of the same standard occasionally occurs. • Interference between different standards Since channel bands in two standard have overlapping parts, therefore the co-channel interference may happen between BSSs of different standards. 11ad 11aj Wei Feng, Tsinghua University

  5. Clustering • In IEEE 802.11aj, clustering mechanism is proposed to reduce interference among multiple BSSs. • Any PCP in the cluster knows SP allocation in other BSSs. • There is no specific spatial reuse among BSSs illustrated in IEEE 802.11aj. Wei Feng, Tsinghua University

  6. SP reuse inside a BSS in IEEE 802.11aj • In IEEE 802.11aj, spatial reuse inside a BSS is supported. • Through transmitting Channel Quality Request and Channel Quality Response, two links are able to get overlapping SPs if they don’t severely interfere with each other. Wei Feng, Tsinghua University

  7. Limitations of SP Reuse Inside A BSS in IEEE 802.11aj • Increasing video service • According to statistics, the percentage of video service is predicted to be 73% in 2017. • One of the most important issue that IEEE 802.11ad and IEEE 802.11aj focused on is video streaming, which mostly requires SP transmission instead of CBAP. • It is hard to satisfy the great demands of SP transmissions of video service simply by SP reuse inside a BSS. 73% Wei Feng, Tsinghua University

  8. Limitations of SP Reuse Inside A BSS in IEEE 802.11aj • Multiple BSSs in a cluster • The time for each BSS to schedule independently sharply decreases if there is many PCPs/APs in a cluster. For example, the average time for SP allocation becomes 1/3 when there are 3 BSSs in a cluster. • Overlapping SPs between BSSs are almost inevitable under heavy traffic load. The interference avoidance in a cluster suggested by IEEE 802.11aj may affect flexibility of SP allocation. Wei Feng, Tsinghua University

  9. Limitations of SP Reuse Inside A BSS in IEEE 802.11aj • Interference level within a BSS is relatively bigger than that among BSSs, resulting in low SPSH efficiency. • The information of SP allocation in other BSSs in a cluster is able to acquired by each PCP, which , however , has not been sufficiently utilized in IEEE 802.11aj. • We need an extension of spatial reuse mechanism in IEEE 802.11aj, which allows SP reuse among different BSSs. Wei Feng, Tsinghua University

  10. Spatial Sharing among Multiple BSSs • If concurrent links do not interfere with each other, then they are allowed to coexist. • Spatial Sharing (SPSH) measurement is designed to build up a database including which pairs of links belonging to different BSSs may coexist (each PCP/AP obtains information about which links in other BSSs do not interfere with links in its own BSS). • SPSH Report is used to exchange information obtained from SPSH measurement period. Through broadcasting SPSH Report, each PCP/AP is able to schedule its SPs that do not interfere with or interfered by links in other BSSs. Wei Feng, Tsinghua University

  11. SPSH Measurement • Utilizing the reserved bit in Clustering Control Element of DMG Beacon, S-PCP/S-AP indicates the start of SPSH measurement and end of it (which is the start of SP spatial sharing). • The SPSH enabled field is defined as: • Set as 1: SPSH measurement starts. In this period, spatial reuse is not allowed and the goal is to find pairs of links in different BSSs that can coexist. • Set as 0: SP reuse is conducted in this scenario, i.e., PCPs/APs of different BSSs are allowed to allocate SPs in overlapping periods. Wei Feng, Tsinghua University

  12. SPSH Measurement • When SPSH Enabled field is 0, each PCP/AP allocates SPs to transmit and receive training sequence. There should be no overlapping between SPs of different BSSs. • When one link is transmitting training sequence, links in other BSSs keep listen with its original beamforming pattern and record SINR value. If the SINR value exceeds threshold, we can define that it does not severely interfered by the measured training link. The extra cost of SPSH measurement is little, since it does not require training of all STAs. • Through SPSH training and measurement, each PCP/AP only gets information to avoid links in other BSSs interfering with links in its own BSS, but cannot guarantee them not interfering the links in other BSSs. Therefore, we need a mechanism to exchange SPSH information between BSSs. Wei Feng, Tsinghua University

  13. SPSH Report • We propose a new MAC element: Spatial Sharing (SPSH) Report, which enables the PCPs/APs to know which links inside it can coexist with links in other BSSs in the same cluster, and thus the corresponding links are allowed to use overlapping SPs. • The SPSH List field is defined as: Wei Feng, Tsinghua University

  14. Performance Evaluation (1) • Throughput performance under different interference level • Each BSS contains one PCP/AP and 5 devices, which are randomly distributed in a 10m×8m cubicle room. Distances between devices in a BSS are relatively smaller that those among BSSs. • Selfish Avoidance refers to that each BSS only schedules its SP to avoid being interfered by other links, but does not consider whether its links would affect links in other BSSs. In Original scenario, spatial sharing is allowed, but no interference avoidance is considered. • The throughput adopting Mutual Avoidance (SPSH Report) almost keeps unchanged in each BSS, which is not affected much by high interference level. Wei Feng, Tsinghua University

  15. Performance Evaluation (2) • Throughput performance comparison between spatial sharing inside a BSS and among BSSs. • Throughput grows with the increase of traffic load, but peaked at a certain traffic load. • Interference level inside a BSS is usually bigger than that among BSSs due to closer distances. Therefore, spatial sharing among BSSs can achieve higher throughput gain. Wei Feng, Tsinghua University

  16. Summary • This submission a MAC mechanism to support SP spatial sharing between multiple co-channel BSSs. The mechanism offers an option to further enhance system throughput. • Modifications to 802.11aj MAC: • In Clustering Control field in DMG Beacon, one reserved bit (i.e., B63) is used to indicate the start of the spatial sharing period and the start of interference training. • SPSH Report Element is added to 11aj. Wei Feng, Tsinghua University

  17. Reference • IEEE P802.11ad, “Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications – Amendment 3: Enhancements for Very High Throughput in the 60 GHz band,” December 2012. • IEEE P802.11aj, “Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) specifications Amendment X: Enhancements for Very High Throughput to Support Chinese Millimeter Wave Frequency Bands (60GHz) ,” January 2014 • K. Huang, Z. Wang, “Millimeter wave communication systems,” John Wiley & Sons Ltd., 2011 Wei Feng, Tsinghua University

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