Adaptive Frequency Reuse in Project m SDD Document Number: S802.16m-07/203r1 Date Submitted: November 12, 2007 Source: I-Kang Fu Pei-Kai Liao and Paul Cheng MediaTek Inc. No. 1 Dusing Rd. 1 Hsinchu Science Park Hsinchu City 300 Taiwan Venue: Atlanta, GA Base Contribution: IEEE C802.16m-07/203r1 Purpose: Propose TGm SDD to have a section Adaptive Frequency Reuse. Notice: This document does not represent the agreed views of the IEEE 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 IEEEs name any IEEE Standards publication even though it may include portions of this contribution; and at the IEEEs 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 Patent Policy: The contributor is familiar with the IEEE-SA Patent Policy and Procedures: and. Further information is located at and.

2 Introduction Motivation –Radio resource is very scarce and adaptive frequency reuse is an important technique to improve overall system capacity improvement The traffic loading in each cell and the received interference level are usually time variant Fixed frequency reuse pattern may be good for initial network configuration under certain assumptions on traffic and user distribution, but how about time variant traffic and user distribution? –IEEE based mobile WiMAX system also supports the technique to apply different frequency reuse factors within the same cell But there is no detailed protocol and measurement mechanisms to facilitate inter-cell coordination and network reconfiguration for adaptive frequency reuse –In section of m SRD, IEEE m shall support flexible frequency re-use scheme. Purpose –Introduce the adaptive (or flexible) frequency reuse to increase overall system capacity A simple example is given to introduce this technology –Propose to enable this functionality in IEEE m system

3 System Model A multi-cell OFDMA system –Cell radius (R) is the same for each cell –Frequency reuse factor (K) is defined as the cluster size The distance between adjacent interfering BSs (D) is function of K: When choosing higher K –Lower received interference –Less available radio resource for each cell Fig. 1 Geometry of interfering cells ( ) by given a frequency reuse factor (cluster size) K

4 Adaptive Frequency Reuse Fig. 2(a) shows a typical reuse partitioning cell structure [An example of adaptive frequency reuse] –Inner cell-regions use a smaller reuse factor due to smaller inter- cell interferences and lower propagation loss Fig. 2(b) illustrates the concept of adaptive frequency reuse –Reuse factor, frame zone size and user served by each frame zone may be adapted from time to time In response to time variant data traffic and interference level of the users –Some kinds of measurement and inter-cell coordination mechanisms are required to enable such functionality Fig. 2 An example [4] of adaptive frequency reuse: (a) divide the cell into Z concentric regions and (b) serve each region by corresponding frame zone with different

5 Proposed Text for the ToC of TGm SDD x.y Adaptive Frequency Reuse [In IEEE m system, the frequency reuse factor applied in each frame zone may be different. For the users in different location or under different interference level, system may serve them by appropriate frame zone with different frequency reuse factor. In order to enable the adaptive frequency reuse in IEEE m system, a measurement mechanism and a inter- cell coordination mechanism will be necessary.] x.y.1 Measurement mechanism for adaptive frequency reuse x.y.2 Inter-cell coordination for adaptive frequency reuse