1. 1 Adaptive Channel Bandwidth Allocations for Femtocell Document Number: IEEE C802.16m-08/1325r1 Date Submitted: 2008-11-05 Source: Yung-Ting Lee, Hua-Chiang Yin E-mail : yungting.lee@coiler.com.tw Coiler Shiann-Tsong Sheu, Chih-Cheng Yang National Central University (NCU) Whai-En Chen National Ilan University (NIU) Kanchei (Ken) Loa,Yi-Hsueh Tsai, Chun-Yen Hsu,Youn-Tai Lee Institute for Information Industry (III) Venue: IEEE 802.16m-08/040-Call for Comments and Contributions on Project 802.16m System Description Document (SDD), on the topic of TGm SDD Femtocells Base Contribution: IEEE 802.16m-08/003r5 Purpose: For discussion and approval by IEEE 802.16m Working Group 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 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 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. Problem statement Since the bandwidth of femtocell backhaul link is not unified, the channel bandwidth allocated for femtocell should be adaptive in order to –avoid wireless channel capacity wastage, –reduce interference, –increase channel reusing factor, and –control congestion in backhaul link.

3. Adaptive Bandwidth Allocation We propose to allocate channel bandwidth for femtocell by taking the associated backhaul bandwidth into considerations. Since the backhaul link could be operated in asymmetric mode (i.e., the DL bandwidth and UL bandwidth are unequal) and the traffic transported over backhaul link is time-varying, the UL and DL channel bandwidths allocated for femtocell should be adaptive. To optimize the network performance, the femtocell is required to periodically measure the backhaul DL/UL available bandwidth as well as current wireless link utilization and report to Network Access Provider (NAP) in order to reconfigure the appropriate parameter set for femtocell.

4. Adaptive bandwidth allocation for TDD Femtocell Two bandwidth allocation methods: –FDM : multiple segments of different spectrum width (in subcarrier or subchannel) –TDM : multiple periods (in subframes) TDD (Femtocell #1) TDD (Femtocell #2) TDD (Femtocell #3) Channel (Freq) TDD (Femtocell #1) TDD (#2) TDD (#3) TDD (Femtocell #1) TDD (#2) TDD (#3) Time Channel (Freq) Time

5. Adaptive bandwidth allocation for FDD Femtocell Two bandwidth allocation methods: –FDM : multiple segments of different width (in subcarrier or subchannel) –TDM : multiple periods (in subframe) FDD DL (Femtocell#1) FDD DL (Femtocell#2) FDD UL (Femtocell#1) Channel (Freq) Time FDD UL (Femtocell#2) FDD DL (Femtocell#1) FDD UL (Femtocell#1) Channel (Freq) Time FDD DL (#2) FDD UL (#2) FDD DL (Femtocell#1) FDD UL (Femtocell#1)

6. Proposed Text [Add the following section 17.x Adaptive Channel Bandwidth Allocation] 17.x Adaptive Channel Bandwidth Allocation Regarding to the backhaul link may operate in asymmetric mode and the traffic transported over wireless link and backhaul link is time- varying, the femtocell may be required to periodically measure the backhaul DL/UL bandwidths as well as wireless channel utilization and report to network in order to reconfigure the appropriate parameter set of channel bandwidth for femtocell.