1. Dynamic Subcarrier/Subchannel Allocation for Interference Mitigation in IEEE802.16m Networks IEEE 802.16 Presentation Submission Template (Rev. 9) Document Number: IEEE C802.16m-08/781r2 Date Submitted: 2008-07-07 Source: Honghai Zhang, Narayan Prasad, Sampath Rangarajan Voice:+01-609-951-2454 Yuefeng Zhou NECE-mail:honghai@nec-labs.comhonghai@nec-labs.com * http://standards.ieee.org/faqs/affiliationFAQ.html Venue: IEEE 802.16 Session #56, Denver, CO, USA IEEE 802.16m-08/024 “Call for Comments and Contributions on Project 802.16m System Description Document (SDD)” In response to the topic: Interference Mitigation Base Contribution: IEEE C802.16m-08/781r2 Purpose: To discuss and adopt the subcarrier/subchannel allocation schemes to mitigate interference among multiple 802.16m base-stations Notice: This document does not represent the agreed views of the IEEE 802.16 Working Group or any of its subgroups. It represents only the views of the participants listed in the “Source(s)” field above. It is offered as a basis for discussion. It is not binding on the contributor(s), who 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 802.16. Patent Policy: The contributor is familiar with the IEEE-SA Patent Policy and Procedures: and.http://standards.ieee.org/guides/bylaws/sect6-7.html#6http://standards.ieee.org/guides/opman/sect6.html#6.3 Further information is located at and.http://standards.ieee.org/board/pat/pat-material.htmlhttp://standards.ieee.org/board/pat

2. Dynamic Subcarrier/Subchannel Allocation for Interference Mitigation in IEEE802.16m Networks Authors: Honghai Zhang, Narayan Prasad, Sampath Rangarajan NEC US Labs Yuefeng Zhou NEC Europe

3. Dynamic Subcarrier/Subchannel Allocation for Interference Mitigation in IEEE802.16m Networks Traditional static subchannel allocation has many limitations –1/1 frequency reuse leads to high interference and small coverage –1/3 frequency reuse reduces interference, and improves coverage, but is at the cost of low average spectrum efficiency. The need of dynamic subchannel/subcarrier allocation –IEEE802.16m needs to improve both coverage and spectrum efficiency –New cells are installed, and switched on and off –Relay stations may be mobile –Traffic load in each cell may be varying

4. Basic Ideas Each BS/Sector is initially allowed to have full frequency reuse but base stations can communicate with each other or through network controllers (e.g., ASN-GW) to dynamically turn on and off some subcarriers/subchannels in order to mitigate interference. There are two possible underlying approaches to support interference mitigation: –Using PUSC subchannels. Channel measurement is performed based on preambles. Each BS/Sector is allowed to turn on or off a subset of physical subcarriers. –Using Band AMC subchannels. Channel measurement is performed based on pilots. Each BS/Sector is allowed to turn on or off a subset of subchannels.

5. Interference Mitigation Using Band AMC Subchannels To enable interference mitigation using Band AMC subchannels, mobiles should report the CQI (Channel Quality Information) as follows. Mobiles select M subchannels with the best SINR and report for each selected subchannel: –the SINR value, –the ratio of the signal from the interfering BS to the signal from the serving BS and the preamble index of the interfering BS (used to identify the neighbor BS), for each of up to K most significant interfering neighbor stations on the selected subchannel. Base stations should convey the above information and the weight of the selected mobile on each subchannel representing the fairness and QoS information to high-layer network controllers (i.e., ASN-GW). High-layer network controllers (i.e., ASN-GW) will dynamically determine the allocation of subchannels to each cell to mitigate interference and ensure fairness. High-layer network controllers can be distributed and co-located with base stations (in which case the base-stations will coordinate among themselves to determine the allocation of subchannels)

6. Interference Mitigation Using PUSC Subchannels To enable interference mitigation using PUSC subchannels, mobiles should report the following information based on preambles: –the SINR value, –the ratio of the signal from the interfering BS to the signal from the serving BS, and the preamble index of the interfering BS (used to identify the neighbor BS), for each of up to K most significant interfering neighbor stations. Base stations should convey the above information and the weight of each mobile representing the fairness and QoS information to high-layer controllers (i.e., ASN-GW). High layer controllers (i.e., ASN-GW) will dynamically determine the allocation of sets of subcarriers to each cell in order to reduce interference and ensure fairness. High layer controllers can be distributed and co-located with base stations (in which case the base-stations will coordinate among themselves to determine the allocation of sets of subcarriers)

7. Proposed Text -- IEEE802.16m base stations shall support periodic neighbor station measurement. The measurement should include the SINR of the current serving BS, the ratio of the signal strength of neighbor stations to the signal strength of the current serving BS, and preamble index of neighbor stations. For PUSC-zones, the signal strength is based on the preambles and the measurement is for each user. For Band-AMC zones, the signal strength is based on the pilots and is measured for M best subchannels for each user. The base stations shall periodically report these measurements and the weights of all users that represent the fairness and QoS information to a network controller (eg. ASN-GW) to facilitate the scheduling algorithms in the network controller to allocate subchannels/subcarriers to each base station. The network controller can be distributed among the base-stations in which the base-stations will coordinate among themselves to allocate subchannels/subcarriers to each base-station.