1. 1 HO between IEEE802.16m femto cell and macro cell IEEE 802.16 Presentation Submission Template (Rev. 9) Document Number: IEEE C802.16m-08/1273 Date Submitted: 2008-10-31 Source: Chie Ming Chou, Fang-Ching (Frank) Ren, Richard Li, Chun-Yen Wang E-mail: chieming@itri.org.tw frank_ren@itri.org.tw ITRI Venue: TGm call for contributions on IEEE 802.16m-08/040. Specific topic : “Support for Femtocells” Base Contribution: N/A Purpose: To be discussed and adopted by TGm. 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. 2 Mobility challenges in femto cell Advertisements –The density of femtocell can be much higher than that of macro cells. –Advertisement for femto cell list is not efficient. Handover –A macro-cell may cover one or several femto cells, when connection is good enough in a macro cell, a MS may not initiate a handover process to access a femto cell. –Since femto cells can have closed access for a limit set of users, most camping/handover requests by the passenger will be rejected. Such frequent futile camping/handover attempts will increase network signaling load and impact end user mobility performance.

3. 3 A two-way handover between macro cell and femto cell When handover from macro cell into femto cell –Challenges listed in previous slide When handover from femto cell into macro cell –Due to the confined range of a femto cell, it needs a fast HO scheme to avoid disconnection Macro cell 1 Macro cell 2 Femto cell 1Femto cell 2

4. 4 Proposal for HO from a macro cell to a femto cell There are 3 steps in proposed mechanism: –Administration of femto cell’s monitoring –Femto cell’s monitoring –Initiate Handover from macro cell to femto cell Administration of femto cell’s monitoring –A femto cell will record the MAC address of its limit set of MSs. If femto cell is open access, then an identifier of no-limitation will be used –The femto cell shall exchange the MAC address of its limit set of MSs to neighboring macro cells. A macro-cell will maintain the mapping between MAC address and corresponding femto cell ID.

5. 5 Proposal for HO from a macro cell to a femto cell (con) Femto cell’s monitoring –Macro cell will notify corresponding femto cell if a allowable MS coming. Verify the MAC address during network entry process. –Macro cell will forward associating uplink resources allocation information of this MS to femto cell. Can be notified by unicast message or force a femto cell to listen the broadcast message of the macro cell –After receiving allocation information, the femto cell can monitor the MS UL data transmission and measure the received signal quality. Received signal quality can include RSSI, SINR, and etc. Initiate Handover from macro cell to femto cell –When monitoring received signal quality is above the threshold, Femto cell will give a request message to the macro cell After receiving this message, the macro cell will originate the handover procedure to handover this MS to requested femto cell

6. 6 Proposal for HO from a macro cell to a femto cell (con) MS Femto cell Macro cell (serving) UL_MAP-IE (broadcast) Data Ranging process Verify User Power on & initialization RNG-REQ (with MAC address) RNG-RSP Notify user coming & corresponding allocation Listen Compare with setting threshold HO_NFY (with action time, resources, & adjustment) MOB_BSHO-REQ (with action time. Resources, adjustment) User negotiation (MAC address) Handover Process

7. 7 Proposal for HO from a femto cell to a macro cell When a MS moves from femto cell to macro cell, the target macro cell always has overlapped coverage with the femto cell. –Scanning process of a MS can be skipped or simplified. The femto cell would select the strongest macro cell as the target macro cell. Due to the small coverage of femto cell, the link conditions between a femto cell and a macro cell may be the same as those between MS and macro cell. –The serving femto-cell can provide the link condition parameters to MS such that the MS can speed up DL/UL synchronization during HO process When a MS which is served by a femto cell finds the link is not good –A MS will directly send the handover request message instead of scanning message –A fast synchronization without contention ranging may be applied

8. 8 Proposal for HO from a femto cell to a macro cell (con) MS1 Macro-cell 1 (target) Femto-cell 1 (serving) Macro-cell 2 preamble HO Initialization preamble BSHO_IND MOB_MSHO-REQ Data Burst RNG-REQ RNG-RSP HO negotiation Link is not good

9. 9 Proposed text 17 Support for Femtocell [insert the following text] 17.x HO process between femto cell and macro cell 17.x.1 HO from a macro cell to a femto cell A femto cell shall exchange the MAC address of its limit set of MSs to neighboring macro cells. A macro cell will notify corresponding femto cell if an allowable MS performs network (re-)entry with this macro cell. The macro cell will also forward uplink resources allocation information of this MS to femto cell. After receiving allocation information, the femto cell can monitor the MS UL data transmission and measure the received signal quality. If monitoring received signal quality is above the threshold, the femto cell will give a request message to the macro cell to trigger a BS-initiate HO process. 17.x.2 HO from a femto cell to a macro cell When a MS which is served by a femto cell finds the link is not good, a MS will directly send the handover request message instead of scanning message. A fast synchronization without contention ranging may be applied.