1. Spatial Sharing Mechanism in 802.11aj (60GHz New Technique Proposal)
Sept 2012
doc.: IEEE /xxxxr0
January 2014
Spatial Sharing Mechanism in aj (60GHz New Technique Proposal)
Date:
Presenter:
Qian Chen
Xiaoming Peng / I2R

2. Hangzhou Millimeter Wave /CWPAN
Author List
January 2014
Name
Company
CHEN, Jiamin
Huawei /CWPAN
CHEN, Qian
I2R / CWPAN
CHIN, Francois
I2R /CWPAN
GAO, Bo
Tsinghua /CWPAN
HAO, Peng
JUST /CWPAN
HONG, Wei
SEU /CWPAN
LI, Dejian
Huawei/CWPAN
LI, Zhiqiang
IMECAS /CWPAN
LIU, Zongru
Hangzhou Millimeter Wave /CWPAN
LIU, Pei
Hisilicon /CWPAN
LU, Su
PENG, Xiaoming
I2R/CWPAN
PNG, Khiam Boon
SUN, Bo
ZTE/CWPAN
WANG, Haiming
YUE, Guangrong
UESTC/CWPAN
ZHUO, Lan
CESI/CWPAN
ZOU, Weixia
BUPT/CWPAN
Qian Chen

3. January 2014
Abstract
This presentation is part and in support of the complete proposal described in IEEE r1 (slides) and IEEE r0 (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
Qian Chen

4. Background: 802.11ad Beamforming TXSS
January 2014
Background: ad Beamforming TXSS
Beamforming training in ad : there are two phases for the beamforming training described in IEEE ad specification [1]: Sector level sweep (SLS) and Beam Refinement Protocol (BRP).
SLS consists of TX sector sweep (TXSS) and RX sector sweep (RXSS) 2
STA 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 ad
Figure 1. An example of TXSS
Qian Chen

5. Background: 802.11ad Beamforming RXSS
January 2014
Background: ad 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 2 3 4
RX Sector Sweep is used to initiate beamforming on this link
Simple Antenna
Device
Source: IEEE ad
Figure 2. An example of RXSS
After the beamforming training, STAs know their best sector ID for transmission
Qian Chen

6. Background: 802.11ad Spatial Sharing Mechanism
January 2014
Background: ad Spatial Sharing Mechanism
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.
Figure 3. Example of spatial sharing assessment
Qian Chen

7. The Proposed Spatial Sharing Mechanism
January 2014
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
January 2014
Source device a
Destination device b
S(a, b) A B 1 E 4 F 2 7 9 12 3 10
Table 1: Beamforming training results among {A, B, E, F}
Source device a
Destination device b
S(a, b) C D 10 E 8 F 12 4 5 3 1 6 9 7
Figure 4. An example of Spatial Sharing
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 2: Beamforming training results among {C, D, E, F}
Slide 8
Qian Chen

9. Procedure of Initial Recommendation (1/2)
January 2014
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).
δ indicates 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)
January 2014
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. The Condition for Spatial Sharing
January 2014
The Condition for Spatial Sharing
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.
Qian Chen

12. The Flow Chart of Proposed Mechanism
January 2014
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 SPe for 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 aj network
Qian Chen

13. Benefits of Proposed Spatial Sharing Mechanism
January 2014
Benefits of Proposed Spatial Sharing Mechanism
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
Qian Chen

14. Modifications to 802.11ad January 2014
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.
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. January 2014
Conclusions
This presentation is part and in support of the complete proposal described in IEEE r1 (slides) and IEEE r0 (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;
Qian Chen

16. January 2014
Reference
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.
r9 - IEEE aj PAR
r7 - IEEE aj 5C
Qian Chen

17. January 2014
Thank YOU
Qian Chen