Date: 2014-01-08

1. Spatial Sharing Mechanism in 802.11aj (60GHz New Technique Proposal) Date: 2014-01-08 Presenter: Qian Chen

2. Author List Qian Chen

3. This presentation is part and in support of the complete proposal described in IEEE 802.11-13-1301r1 (slides) and IEEE 802.11-13-1302r0 (text) This document is to propose a spatial sharing mechanism to assess two pair of devices with directional transmission that can be used concurrently for spatial sharing, based on the priori information of beamforming training results among devices in a network; The proposed method applies to the initial recommendation of resource allocation in either scheduled slots or contention based slots, it is only a recommended procedure, instead of mandatory procedure; This presentation is in response to the comments made for IEEE 802.11-13-1292-02. Abstract Qian Chen

4. Beamforming training in 802.11ad : there are two phases for the beamforming training described in IEEE 802.11ad specification [1]: Sector level sweep (SLS) and Beam Refinement Protocol (BRP). SLS consists of TX sector sweep (TXSS) and RX sector sweep (RXSS) Background: 802.11ad Beamforming TXSS STA 2 1 3 4 • For the initial connection between two devices (Station (STA) and PBSS Control Point/Access Point (PCP/AP)), STA will receive with a quasi-omni-directional antenna while PCP sends a sequence of frames covering different TX sectors or vice versa. PCP/AP Source: IEEE 802.11ad Figure 1. An example of TXSS Qian Chen

5. Background: 802.11ad Beamforming RXSS • A device with a simple antenna may not have enough TX gain to reach a distant receiver that is using an omni-directional receiving antenna • RX Sector Sweep may be employed by the device with the higher performance antenna system • Allows a simple antenna device, like a handset, to connect at greater range 1 RX Sector Sweep is used to initiate beamforming on this link 2 4 3 Simple Antenna Device Source: IEEE 802.11ad Figure 2. An example of RXSS After the beamforming training, STAs know their best sector ID for transmission Qian Chen

6. Assume that beamforming training has been done: STAs know their best Sector ID for transmission The existing spatial sharing mechanism in [1]: • Spatial sharing can only be done in Service Period (SP), not Contention Based Access Period (CBAP) • Both existing SP and candidate SP need to perform measurement before usage • The mechanism is not very efficient. From PCP/AP’s perspective, it is a blind selection process. Background: 802.11ad Spatial Sharing Mechanism Figure 3. Example of spatial sharing assessment Qian Chen

7. The Proposed Spatial Sharing Mechanism Assumption: • The beamforming training results between any two STAs will be kept by PCP/AP with the best selected sector IDs. Proposed solution: • A method to assess two pair of devices with directional transmission that can be used concurrently for spatial sharing, based on the priori information of beamforming training results among devices in a network Slide 7 Qian Chen

8. Example – Spatial Sharing in 802.11ad Assumption: • Each STA has 12 sectors with 30 degree transmission angel. • The beamforming training results are shown in Table 1 and 2 • PCP/AP has scheduled SP1 and SP2 for pair (A, B) and (C, D), respectively. Purpose: • To recommend an initial SP for the candidate SP with pair (E, F) from the existing SP set {SP1, SP2} for spatial sharing. Table 1: Beamforming training results among {A, B, E, F} Figure 4. An example of Spatial Sharing Table 2: Beamforming training results among {C, D, E, F} Slide 8 Qian Chen

9. Procedure of Initial Recommendation (1/2) • First, PCP/AP uses Table 1 to check whether SP1 is available for the candidate SP with pair (E, F). • From Table 1, A and B choose Sector 1 and 7 (blue areas) to communicate with each other. E and F intend to use Sector 3 and 7, respectively.   • Neither E nor F would be affected by A, because the beamforming results show that the Sector 4 and 2 would be the best sector for A to transmit to E and F, respectively, which are different with Sector 1. • The sector number difference between two best sectors S(A, B) and S(A, E) , denoted by δA→B, E, is calculated as 3; Similarly, δA→B, F = 1. Thus, A’s transmission has no interference to E and F.   Figure 4. An example of Spatial Sharing • However, if B is transmitting to A with Sector 7, E would be affected by B because the same Sector 7 is selected for B to transmit to A and E. In this case, δB→A, E= 0.  • Therefore, the existing SP1 does Not satisfy with the condition of spatial sharing with the candidate SP with pair (E, F). δindicates the sector number difference between two best sectors S(a, b) and S(a, c) chosen by one source device a to two different destination devices b and c. Slide 9 Qian Chen

10. Procedure of Initial Recommendation (2/2) • Second, PCP/AP uses Table 2 to check whether SP2 is available for the candidate SP with pair (E, F). Thus, we have δC→D, E= 2 δC→D, F = 2 δD→C, E = 1 δD→C, F = 1 δE→F, C = 1 δE→F, D = 2 δF→E, C = 1 δF→E, D = 2 • Since the minimum value of the above δ’s is larger than 0, the existing SP2 can be recommended as an initial SP for the candidate SP with pair (E, F). Figure 4. An example of Spatial Sharing Finally, PCP/AP responds to E and F the best initial recommendation with the result of SP2. Slide 10 Qian Chen

11. Spatial sharing condition: As long as any source STA involved in an existing SP does not employ the same transmit sector with the one that it employs to communicate with any other STA involved in a candidate SP, and vice versa, the PCP/AP may schedule this existing SP and the candidate SP time-overlapping with each other for spatial sharing. Furthermore, if a pair of existing SP and candidate SP satisfies the above condition, the larger the number of difference between any two of transmit sectors employed by a source STA to communicate with its destination STA and with any other STA involved in the other SP, the more the space to implement spatial sharing and interference mitigation among them. Therefore, the parameter δ is considered as the criteria of the selection for the best initial slot that can be scheduled slot or contention based slot. The Condition for Spatial Sharing Qian Chen

12. The Flow Chart of Proposed Mechanism Start Finish the traverse of the scheduled transmission set {x, y}e in this SPe? PCP/AP checks the next existing SPefor a candidate SPc with transmission pair (i, j) and set δ*e = 0; N Y For each scheduled transmission pair (x, y) in this SPe Add SPe into initial recommendation set {SPe} with δ*e Does any of the following cases occur between the intended transmission pair (i,j) and (x, y) ? S(x, i) == S(x, y) || S(x, j) == S(x, y) || S(y, i) == S (y, x) || S(y, j) == S(y, x) || S(i, x) == S(i, j) || S(i, y) == S(i, j)|| S(j, x) == S(j, i) || S(j, y) == S(j, i) N Finish the traverse of the existing SP set {SPe}? Y Y Search the best initial recommendation from {SPK} with the selection criteria of the largest δ*e N Calculate the values of δ If δ < δ*e δ*e= δ; End Figure 5. Flow chart of the proposed method for IEEE 802.11aj network Qian Chen

13. Accurate allocation of spatial sharing among pair of devices; • Fast allocation of spatial sharing among pair of devices; • Avoids unnecessary operation of measuring and report feedback among those pair of devices that may cause interference with each other if they transmit concurrently; • Power saving of the resource allocation for the spatial sharing as it can significantly reduce the number of pair of devices that can be used for measuring and report feedback Benefits of Proposed Spatial Sharing Mechanism Qian Chen

14. PCP/AP will be informed and updated of the results of the beamforming training among non-PCP/non-AP STAs. • At the last step of beamforming phase, non-PCP/non-AP initiator (responder) must notify PCP/AP through a SSW-Report frame which contains a modified SSW Feedback field indicating Source AID, Destination AID, Sector Select, DMG Antenna Select, SNR Report, etc. Modifications to 802.11ad • The Source AID field identifies the initiator (responder) transmitting the SSW-Feedback (SSW-ACK) frame. • The Source AID field identifies the STA that is the intended responder (initiator) of beamforming. Figure 6. SSW-Report frame format Qian Chen

15. This presentation is part and in support of the complete proposal described in IEEE 802.11-13-1301r1 (slides) and IEEE 802.11-13-1302r0 (text) Proposed a spatial sharing mechanism to assess two pair of devices with directional transmission that can be used concurrently for spatial sharing, based on the priori information of beamforming training results among devices in a network; The proposed method applies to the initial recommendation of resource allocation in either scheduled slots or contention based slots, it is only a recommended procedure, instead of mandatory procedure; Conclusions Qian Chen

16. In the IEEE P802.11adTM-2012 Standard “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. • 11-12-0140r9 - IEEE 802.11.aj PAR • 11-12-0141r7 - IEEE 802.11.aj 5C Reference Qian Chen

17. Thank YOU Qian Chen