Handover control method in a wireless access system, relay station and base station

Abstract

The present invention provides a handover control method in a wireless access system, a relay station and a base station for performing handover control in a mobile multi-hop relay wireless access system such that the wireless access system is enabled to cover a wider area. To achieve the above object, the present invention provides a handover control method in a wireless access system, wherein the wireless access system comprises a mobile station and a base station, which receive and send message via a wireless channel, and further comprises a relay station for forwarding message from the mobile station and the base station under control of the base station, characterized in that the method comprising a relay station measure and arbitration step in which the relay station measures the message and arbitrates whether to relay the message, and a base station measure and handover step in which the base station measures the message and arbitrates whether to perform handover.

1 . (canceled) 
     
     
         2 . A method for control of a handover of a mobile station in a wireless access system, comprising:
 receiving an uplink message from a mobile station at a relay station via a wireless channel;   forwarding the uplink message from the relay station to the base station when it is determined that the signal quality of the uplink message measured at the relay station exceeds a predetermined value;   receiving the uplink message via the wireless channel at the base station from at least one of the mobile station and the relay station; and   at the base station, causing initiation of a handover of the mobile station involving the relay station based at least in part on a measured signal quality of the uplink message as received at the base station.   
     
     
         3 . The method according to  claim 2  wherein the uplink message includes at least one of (i) a ranging request message or (ii) an uplink data burst. 
     
     
         4 . The method according to  claim 2  wherein the wireless channel includes an uplink channel and a downlink channel. 
     
     
         5 . The method according to  claim 2 , further comprising:
 measuring signal quality of the uplink message at the relay station; and   comparing the measured signal quality of the uplink message to the predetermined value at the relay station.   
     
     
         6 . The method according to  claim 2  wherein the uplink message is forwarded from the relay station to the base station via the wireless channel through a dedicated control information relay zone reserved for forwarding uplink control information. 
     
     
         7 . The method according to  claim 2  wherein involving the relay station in the handover of the mobile station means said handover is at least one of (i) from the relay station and (ii) to the relay station. 
     
     
         8 . The method according to  claim 2 , further comprising:
 measuring signal quality of the uplink message(s) received at the base station;   comparing the measured signal quality (qualities) and link budgets at the base station; and   at the base station, determining whether to initiate the handover based at least in part on the comparing.   
     
     
         9 . The method according to  claim 8  wherein the determining whether to initiate the handover is based at least in part on one or more of channel load, multi-hop bandwidth efficiency, and transmission power. 
     
     
         10 . A relay station configured to operate in a wireless access system, comprising:
 a receiver configured to receive an uplink message from a mobile station via a wireless channel; and   a transmitter configured to forward the uplink message to the base station via the wireless channel when it is determined that the signal quality of the uplink message exceeds a predetermined value.   
     
     
         11 . The relay station according to  claim 10  wherein the transmitter is configured to forward the uplink message via the wireless channel through a dedicated control information relay zone reserved for forwarding uplink control information. 
     
     
         12 . The relay station according to  claim 10  wherein the uplink message includes at least one of (i) a ranging request message or (ii) an uplink data burst. 
     
     
         13 . The relay station according to  claim 10  wherein the wireless channel includes an uplink channel and a downlink channel. 
     
     
         14 . The relay station according to  claim 10 , further comprising:
 a measurement circuit configured to measure signal quality of the uplink message; and   at least one processor configured to compare the measured signal quality of the uplink message to the predetermined value.   
     
     
         15 . A base station configured to operate in a wireless access system, comprising:
 a receiver configured to receive an uplink message generated by a mobile station from at least one of the mobile station and a relay station forwarding the uplink message via a wireless channel;   a measurement circuit configured to measure signal quality of the uplink message; and   at least one processor configured to cause initiation of a handover of the mobile station involving the relay station based at least in part on the measured signal quality of the uplink message as received at the base station.   
     
     
         16 . The base station according to  claim 15  wherein the receiver is configured to receive the uplink message via the wireless channel through a dedicated control information relay zone reserved for forwarding uplink control information. 
     
     
         17 . The base station according to  claim 15  wherein the uplink message is received from the relay station after the relay station received the uplink message from the mobile station and determined the signal quality exceeded a predetermined value. 
     
     
         18 . The base station according to  claim 15  wherein the uplink message includes at least one of (i) a ranging request message or (ii) an uplink data burst. 
     
     
         19 . The base station according to  claim 15  wherein the wireless channel includes an uplink channel and a downlink channel. 
     
     
         20 . The base station according to  claim 15  wherein involving the relay station in the handover of the mobile station means said handover is at least one of (i) from the relay station and (ii) to the relay station. 
     
     
         21 . The base station according to  claim 15  wherein the at least one processor is configured to compare the measured signal quality (qualities) and link budgets and to determine whether to initiate the handover based at least in part on the comparing. 
     
     
         22 . The base station according to  claim 21  wherein the at least one processor is configured to determine whether to initiate the handover based at least in part on one or more of channel load, multi-hop bandwidth efficiency, and transmission power. 
     
     
         23 . A method for control of a handover of a mobile station in a wireless access system, comprising:
 at a current base station, receiving a mobile handover request generated by a mobile station, wherein the mobile station and current base station are associated with a wireless access system and the mobile station is currently within coverage of the current base station;   sending a pre-handover notification request message from the current base station to at least one neighboring base station, each neighboring base station associated with the wireless access system; and   receiving a pre-handover notification response message at the current base station from one or more neighboring base stations to which the pre-handover notification request message was sent, wherein the pre-handover notification response message from at least one of the one or more neighboring base stations includes signal quality information relating to the corresponding ranging request message or uplink data burst received by a relay station within coverage of the corresponding neighboring base station.