Enhancement of RTS and ACK Design for the IEEE 802.22.1 Standard September 2006 doc.: IEEE 802.22-06/0128r1 January 2007 Enhancement of RTS and ACK Design for the IEEE 802.22.1 Standard IEEE P802.22 Wireless RANs Date: 2007-1-5 Authors Name Company Address Phone email Linjun Lv Huawei Technologies Shenzhen, China 86-755-28973119 lvlinjun@huawei.com Zhou Wu 86-755-28979499 wuzhou@huawei.com Mingwei Jie 86-755-28972660 jiemingwei@hauwei.com Zhixue Shi Shizhixue@hauwei.com Soo-Young Chang Davis, CA, U.S. 1-916 278 6568 sychang@ecs.csus.edu Jianwei Zhang Shanghai, China 86-21-68644808 zhangjianwei@huawei.com Notice: This document has been prepared to assist IEEE 802.22. It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein. Release: The contributor grants a free, irrevocable license to the IEEE to incorporate material contained in this contribution, and any modifications thereof, in the creation of an IEEE Standards publication; to copyright in the IEEE’s name any IEEE Standards publication even though it may include portions of this contribution; and at the IEEE’s sole discretion to permit others to reproduce in whole or in part the resulting IEEE Standards publication. The contributor also acknowledges and accepts that this contribution may be made public by IEEE 802.22. Patent Policy and Procedures: The contributor is familiar with the IEEE 802 Patent Policy and Procedures http://standards.ieee.org/guides/bylaws/sb-bylaws.pdf including the statement "IEEE standards may include the known use of patent(s), including patent applications, provided the IEEE receives assurance from the patent holder or applicant with respect to patents essential for compliance with both mandatory and optional portions of the standard." Early disclosure to the Working Group of patent information that might be relevant to the standard is essential to reduce the possibility for delays in the development process and increase the likelihood that the draft publication will be approved for publication. Please notify the Chair Carl R. Stevenson as early as possible, in written or electronic form, if patented technology (or technology under patent application) might be incorporated into a draft standard being developed within the IEEE 802.22 Working Group. If you have questions, contact the IEEE Patent Committee Administrator at patcom@iee.org. Ed Callaway, Motorola

September 2006 doc.: IEEE 802.22-06/0128r1 January 2007 Abstract We propose an enhanced RTS and ACK design for the IEEE 802.22.1 Enhanced Detection of Part 74 Devices standard. Ed Callaway, Motorola

September 2006 doc.: IEEE 802.22-06/0128r1 January 2007 Background IEEE 802.22.1 Standard is under development to enhance harmful interference protection for low-power licensed as secondary devices operating in TV Broadcast Bands (under Title 47 of the Code of Federal Regulations (CFR) in the USA and equivalent devices in other regulatory domains). Target technologies considered for signalling the presence of low-power licensed devices are different from the sensing and cognitive radio technologies that are being considered elsewhere in 802.22. Motorola’s proposal has been selected as baseline in Sept. 2006 meeting. Ed Callaway, Motorola

Baseline Superframe Format September 2006 doc.: IEEE 802.22-06/0128r1 January 2007 Baseline Superframe Format BURSTS Sync N N-1 1 BEACON PSDU … ANP Frame period BEACON Rx period Ed Callaway, Motorola

Baseline Receive Period and RTS Burst September 2006 doc.: IEEE 802.22-06/0128r1 January 2007 Baseline Receive Period and RTS Burst An SPD may send an RTS burst in the receive period, in order to send its beacon. If the SPD receives an ACK from the PPD during the ANP, the SPD shall transmit its beacon frame during the following superframe. If the SPD received a NACK during the ANP, it shall not transmit a beacon frame, and Bits: 0-3 4-15 RTS codeword Sync SHR PHY payload Format of the RTS burst Bits: 0 1 2 3 4 5 6 7 8 9 10 11 Format of the RTS codeword field Ed Callaway, Motorola

September 2006 doc.: IEEE 802.22-06/0128r1 January 2007 Baseline ANP Burst The ANP burst is used by the PPD to indicate whether or not it has received a request to transmit (i.e., an RTS burst) from an SPD in the receive period immediately preceding the ANP. If it has received a request, the PPD shall transmit an ACK. Note that the received request must be error-free in order to transmit an ACK. Otherwise, it shall transmit a NACK. Bits: 0 1 2 3 ACK NACK Transmission Ed Callaway, Motorola

When RTS Bursts Collided September 2006 doc.: IEEE 802.22-06/0128r1 January 2007 When RTS Bursts Collided PPD shall transmit a NACK and continue. SPD shall use a random backoff time before requesting to send another RTS burst and continue. Ed Callaway, Motorola

September 2006 doc.: IEEE 802.22-06/0128r1 January 2007 Problems to Be Solved When a collision happens, PPD usually can not distinguish different SPDs effectively ; It may cause waste of the superframes and more interference to the protected devices . Ed Callaway, Motorola

Proposed Method (1) Analysis: January 2007 Proposed Method (1) Analysis: In order to distinguish different SPDs effectively when a collision happens, we suggest use the RTS code enough. If the number of elements of RTS collection is n and the number of elements of PN collection is n, then the probability that PPD cannot distinguish two different SPDs is 1/(n*m). In order to use next superframe, when a collision happens, the PPD needs to send an ACK including the ‘ID’.

It is assumed that PN sequences are as following: September 2006 doc.: IEEE 802.22-06/0128r1 January 2007 Proposed Method (2) It is assumed that PN sequences are as following: Index PN Value 1 00000000 2 01010101 3 00110011 4 01100110 5 00001111 6 01011010 7 00111100 8 01101001 Ed Callaway, Motorola

Our selected RTS (orthogonal circular) September 2006 doc.: IEEE 802.22-06/0128r1 January 2007 Proposed Method (3) Our selected RTS (orthogonal circular) Index RTS Values 1 010010111000 2 010111000010 3 111000010010 4 000010010111 Ed Callaway, Motorola

Proposed Method (4) Comparison Table January 2007 September 2006 doc.: IEEE 802.22-06/0128r1 January 2007 Proposed Method (4) Comparison Table SPD Identifier PN Values RTS Values 1 00000000 010010111000 2 010111000010 3 111000010010 4 000010010111 5 01010101 6 7 8 9 00110011 10 11 12 13 01100110 14 15 16 17 00001111 Ed Callaway, Motorola

Comparison Table (cont’d) September 2006 doc.: IEEE 802.22-06/0128r1 January 2007 Proposed Method (5) Comparison Table (cont’d) SPD Identifier PN Values RTS Values 18 00001111 010111000010 19 111000010010 20 000010010111 21 01011010 010010111000 22 23 24 25 00111100 26 27 28 29 01101001 30 31 32 Ed Callaway, Motorola

Proposed Method (6) Perform the following Procedure: January 2007 Proposed Method (6) Perform the following Procedure: SPD wants to send beacon in next superframe and send RTS in present superframe Rx Period. Before it sends RTS, it should select an RTS and a PN from the  orthogonal circular RTS collection and PN collection. After then it sends the RTS; If PPD receives several RTSs from SPDs, PPD should select one of them to send data in next superframe, and sends corresponding ACK including an SPD Identifier corresponding to the selected PN and RTS; if PPD does not receive an RTS, then it sends NACK; After receiving an ACK, SPD should decode it and collate its PN and RTS which it has sent before. Then if the PN and the RTS are equal to the ACK in the comparison table, it can send data in next superframe; otherwise, it does not send and before next RTS it should back off a random time. Then it continues the process.

Proposed Method (7) January 2007 In order to support this procedure, we need to change the format of ACK. Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 high low For the binary sequence of the SPD Identifier, high bit is corresponding to the same high bit. For example, for a binary sequence 000011 of ID 3, the sequence in ACK is 1 NACK format is shown following 1

Summary Enhancement for RTS code and ACK transmission is proposed; January 2007 Summary Enhancement for RTS code and ACK transmission is proposed; This method can help PPD to distinguish different SPDs effectively; This method can help to utilize superframe more effectively; This method is very simple to implement.