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Date: 2013-07-16

Spatial Sharing Mechanism in 802.11aj (60GHz). Date: 2013-07-16. Presenter:. Author List. 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).

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Date: 2013-07-16

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  1. Spatial Sharing Mechanism in 802.11aj (60GHz) Date: 2013-07-16 Presenter: Francois Chin

  2. Author List Francois Chin

  3. 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 Francois Chin

  4. 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 /reception Francois Chin

  5. 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 Francois Chin

  6. Proposed Spatial Sharing Selection Method Proposed Method: • A method to recommend an existing SP for spatial sharing with the new pair of devices with directional transmission • Existing SP has one or more pairs of devices with directional transmission, all spatial sharing Assumption: • PCP/AP is updated with the beamforming training results between any two STAs, in terms of best selected sector IDs. Slide 6 Francois Chin

  7. 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 7 Francois Chin

  8. 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 8 Francois Chin

  9. 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-F pair with the best initial recommendation of SP2. Slide 9 Francois Chin

  10. 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 sector number difference δ, 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 better chance 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 Francois Chin

  11. The Flow Chart of Proposed Method 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 Francois Chin

  12. Accurate 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; • Fast allocation of spatial sharing among pair of devices; • 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 Selection Method Francois Chin

  13. 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) shall notify PCP/AP through a SSW-Report frame which contains an SSW Report field indicating Source AID, Destination AID, Sector Select, DMG Antenna Select, SNR Report, etc. Modifications to 802.11ad • The Source AID field identifies the transmitter that is the intended initiator (responder) of beamforming. • The Source AID field identifies the receiver that is the intended responder (initiator) of beamforming. Figure 6. SSW-Report frame format and Initiator (Responder) Link Report field Francois Chin

  14. Proposed a method to recommend an existing SP for spatial sharing with the new pair of devices with directional transmission • based on the priori information of beamforming training results among devices • Existing SP has one or more pairs of devices with directional transmission, all spatial sharing • Proposed SSW-report frame format for non-PCP/non-AP STAs to report the results of the beamforming training, in terms of best sector IDs, to PCP/AP Conclusions Francois Chin

  15. [1] 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. Reference Francois Chin

  16. Thank YOU Francois Chin

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