[Proposed Burst Allocation Method Relating to DS/US-MAP] March 2007 doc.: IEEE 802.22-07-0xxx-00-0000 July 2007 [Proposed Burst Allocation Method Relating to DS/US-MAP] IEEE P802.22 Wireless RANs Date: 2007-07-12 Authors: 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. Chang-Joo Kim, ETRI Chang-Joo Kim, ETRI

July 2007 Abstract In this presentation, we propose the burst allocation (burst mapping) method for WRAN system, which is related to DS and US MAP design. In order to develop the best burst allocation method, several features should be considered as follows, Required bit size of DS/US-MAP IE Time diversity gain Decoding latency till delivering to MAC A bundle of 7 OFDMA symbols for US burst Contention-based burst in US (Ranging/BW Request/UCS notification, CBP) Chang-Joo Kim, ETRI

Required Bit Size of DS/US-MAP IE July 2007 Required Bit Size of DS/US-MAP IE The linear allocation only needs to define the length of the burst, on the other hand, the rectangular allocation needs to define the start point and end point of the burst. Though, in case of linear allocation, a CPE (or a BS) should trace the history of the length for foregoing CPEs, it may not a big burden to each CPE. In the point of the required bit size, a linear allocation is more fascinating than a rectangular allocation. Chang-Joo Kim, ETRI

July 2007 Time Diversity Gain If the terminal has a high mobility, such as 802.16e, we have to consider the diversity effect in the time direction. In that case, it is desirable to allocate the burst in the time direction first (i.e., linear-horizontal scheme). However, in the case of fixed WRAN system, it seems that there is no rationale to follow the allocation method same as 802.16e. For WRAN system, it is possible to allocate the burst in the frequency direction first (i.e., linear-vertical scheme) without any deterioration. Chang-Joo Kim, ETRI

Decoding Latency till Delivering to MAC July 2007 Decoding Latency till Delivering to MAC To minimize the decoding latency as much as possible Allocate the burst using the linear-vertical scheme Or allocate the burst using the rectangular scheme so that it occupy a reasonable time and frequency area When the burst is allocated using the linear-horizontal scheme in the time direction first using only length, the decoding latency could be drastically increased, particularly in the downstream in which more OFDM symbols could be allocated. Chang-Joo Kim, ETRI

Worse Case of Decoding Latency July 2007 Worse Case of Decoding Latency For Burst 2 of DS sub-frame, though the length of burst is small, the decoding latency is large. Chang-Joo Kim, ETRI

A Bundle of 7 OFDMA Symbols for US Burst July 2007 A Bundle of 7 OFDMA Symbols for US Burst In upstream, the number of OFDMA symbols allocated to a CPE needs to be at least 7 to access sufficient pilot carriers for best channel estimation. Therefore, each row of the subchannels within the burst should include at least 7 OFDMA symbols. In case that US sub-frame contains 7 to 13 OFDMA symbols, all OFDMA symbols can be included to only one burst. In case that US sub-frame contains more than 14 OFDMA symbols, the OFDMA symbols can be divided into several burst. Chang-Joo Kim, ETRI

Hybrid Burst Mapping in Upstream July 2007 Hybrid Burst Mapping in Upstream To reduce the decoding latency, the burst should be allocated by the bundle of 7 OFDMA symbols. On the other hand, if a CPE needs to transmit at maximum EIRP, the coverage of CPE will be larger if it uses more OFDMA symbols in time and less subchannels in frequency so that the power per subchannel can be maximized. So we propose the hybrid burst mapping as follows, For latency-sensitive burst, the burst will be allocated in terms of at least 7 OFDMA symbols width For power-sensitive burst, the burst will be allocated in full width of US sub-frame. In hybrid burst mapping, the type of Diversity subchannel can be identified by using 2 bits in US-MAP IE. Chang-Joo Kim, ETRI

Segmentation for Latency-Sensitive Burst July 2007 Segmentation for Latency-Sensitive Burst An US sub-frame can be divided into several segment in terms of at least 7 OFDMA symbols width. Each burst can be defined within the segment. If the total OFDMA symbols within US sub-frame excluding CBP packet are not divided into 7, total_OFDMA_symbols % 7 are included to the last segment. If the total OFDMA symbols within US sub-frame excluding CBP packet are X, then X = 7*Y+Z=7*(Y-1)+(7+Z), here, Z<7. Thus, there are (Y-1) segment with 7 OFDMA symbols width and 1 segment with (7+Z) OFDMA symbols width in the time direction. The segments are sequentially located from left to right in the time direction. For example, if the total number of OFDMA symbols of US sub-frame excluding CBP packet (X) are 16, there are 1 segment with 7 OFDMA symbols width and 1 segment with 9 OFDMA symbols width in the time direction. Chang-Joo Kim, ETRI

Proposed Modification of US-MAP IE July 2007 Proposed Modification of US-MAP IE Chang-Joo Kim, ETRI

Contention-Based Burst in US July 2007 Contention-Based Burst in US A rectangular burst would be allocated for the function of Ranging, BW Request, and UCS notification At the end of US sub-frame, the CBP packet would be transmitted for self-coexistence with rectangular shape Chang-Joo Kim, ETRI

Proposed Partition of Subchannel Zone July 2007 Proposed Partition of Subchannel Zone AMC and Diversity zones are divided in the frequency domain with the rectangular shape. After identifying the AMC zone using DS-MAP, the rest excluding the AMC zone is assigned to the Diversity zone. The AMC subchannel starts from the next OFDMA symbol of the FCH, DS/US-MAP, and DCD/UCD. The CPE have to know the range of AMC subchannel from the DS-MAP. If AMC subchannel start from the following the preamble symbol, the CPE would not know the information on subcarrier de-allocation of Diversity subchanel, at least for the first frame within superframe. The rest subchannel(s) in the header field will be allocated to the Diversity subchannel for data transmission. Chang-Joo Kim, ETRI

Proposed Partition of Subchannel Zone (Cont’d) July 2007 Proposed Partition of Subchannel Zone (Cont’d) Chang-Joo Kim, ETRI

July 2007 Proposed Burst Structure (In case that US sub-frame contains 7 to 13 OFDMA symbols) Chang-Joo Kim, ETRI

July 2007 Proposed Burst Structure (In case that US sub-frame contains more than 14 OFDMA symbols) Chang-Joo Kim, ETRI

July 2007 Proposed Burst Structure (In case that the remains of orange zone is less than 7 OFDMA symbols) Chang-Joo Kim, ETRI

July 2007 Conclusions We propose to use only length (i.e., linear scheme) for DS and US burst allocation. Each upstream burst has to contain at least 7 OFDMA symbols at each row of subchannel. For Diversity subchannel, the DS and US burst are allocated by using linear-vertical scheme and linear-horizontal scheme within burst, respectively. For AMC subchannel, the DS and US burst are allocated by using linear-vertical scheme within burst. We propose the hybrid burst mapping to deal efficiently with both latency- and power-sensitive burst. Chang-Joo Kim, ETRI