Mobile wireless communication system and method of carrying out handover in the system

Abstract

When a strength of an electric field for receiving wireless in downlink is equal to or smaller than a predetermined strength, the mobile communication terminal device 105 transmits a retrieval request to the retrieval server 102 through the first wireless station 103 to cause the retrieval server to start selecting a new wireless station, changes at least one of profiles (UTP) for transmitting wireless in uplink, and notifies the first wireless station 103 of the changed profile(s). The first wireless station 103 changes a profile or profiles (URP) for receiving wireless in uplink, corresponding to the changed profile(s) (UTP) for transmitting wireless in uplink, received from the mobile wireless terminal device, changes at least one of profiles (DTP) for transmitting wireless in downlink, and notifies the mobile wireless terminal device of the changed profile(s) (DTP) for transmitting wireless in downlink.

1 . A mobile wireless communication system comprising:
 a network;   a plurality of wireless stations connected in wireless communication to said network; and   a mobile communication terminal device making communication, keeping a first wireless link comprising a pair of uplink and downlink with one of said wireless stations,   wherein when said mobile communication terminal device determines that communication quality of said downlink is low, said mobile communication terminal device starts to establish a second wireless link with a new wireless station, changes at least one of profiles (UTP) for transmitting wireless signal in said uplink, and notifies a wireless station through which said mobile communication terminal device is making wireless communication of the changed profile(s),   said wireless station changes a profile or profiles (URP) for receiving wireless signal in uplink, corresponding to the changed profile(s) (UTP) for transmitting wireless signal in said uplink, received from said mobile communication terminal device.   
     
     
         2 . The mobile wireless communication system as set forth in  claim 1 ,
 wherein said wireless station changes at least one of profiles (DTP) for transmitting wireless signal in said downlink, and notifies said mobile communication terminal device of the changed profile(s) (DTP) for transmitting wireless signal in said downlink,   said mobile communication terminal device changes a profile or profiles (DRP) for receiving wireless signal in downlink, corresponding to the changed profile(s) for transmitting wireless signal in said downlink, received from said wireless station.   
     
     
         3 . The mobile wireless communication system as set forth in  claim 1 , wherein said mobile communication terminal device determines that the communication quality of said downlink is low when a strength of an electric field for receiving wireless signal in said downlink is equal to or smaller than a predetermined strength. 
     
     
         4 . The mobile wireless communication system as set forth in  claim 1 , wherein said mobile communication terminal device determines that the communication quality of said downlink is low when a number of packet collisions exceeds a predetermined threshold. 
     
     
         5 . The mobile wireless communication system as set forth in  claim 1 , wherein said mobile communication terminal device determines that the communication quality of said downlink is low when propagation delay of packets exceeds a predetermined threshold. 
     
     
         6 . The mobile wireless communication system as set forth in  claim 1 , wherein said wireless station is comprised of an access point having a WLAN (Wireless Local Area Network) function. 
     
     
         7 . The mobile wireless communication system as set forth in  claim 1 , wherein said mobile communication terminal device changes at least one of profiles (UTP) for transmitting wireless signal in said uplink, based on a strength of an electric field for receiving wireless signal, an electric power for transmitting wireless signal, and an error rate. 
     
     
         8 . The mobile wireless communication system as set forth in  claim 7 , wherein at least one of profiles (UTP) for transmitting wireless signal in said uplink is modulation. 
     
     
         9 . The mobile wireless communication system as set forth in  claim 7 , wherein at least one of profiles (UTP) for transmitting wireless signal in said uplink is a coding rate. 
     
     
         10 . The mobile wireless communication system as set forth in  claim 7 , wherein said first wireless link is established in accordance with OFDMA (Orthogonal Frequency Division Multiple Access), and at least one of profiles (UTP) for transmitting wireless signal in said uplink is a number of sub-channels in said OFDMA. 
     
     
         11 . The mobile wireless communication system as set forth in  claim 2 , wherein said wireless station, on receipt of notification that a profile or profiles for transmitting wireless signal in said uplink has(have) been changed, from said mobile communication terminal device, changes at least one of profiles (DTP) for transmitting wireless signal in said downlink, based on a strength of an electric field for receiving wireless signal, an electric power for transmitting wireless signal, and an error rate. 
     
     
         12 . The mobile wireless communication system as set forth in  claim 11 , wherein at least one of profiles (DTP) for transmitting wireless signal in said downlink is modulation. 
     
     
         13 . The mobile wireless communication system as set forth in  claim 11 , wherein at least one of profiles (DTP) for transmitting wireless signal in said downlink is a coding rate. 
     
     
         14 . The mobile wireless communication system as set forth in  claim 11 , wherein said first wireless link is established in accordance with OFDMA (Orthogonal Frequency Division Multiple Access), and at least one of profiles (DTP) for transmitting wireless signal in said downlink is a number of sub-channels in said OFDMA. 
     
     
         15 . The mobile wireless communication system as set forth in claim wherein said mobile communication terminal device includes a plurality of wireless interfaces different from each other with respect to a communication system,
 said mobile communication terminal device simultaneously establishes a plurality of wireless links with the plurality of wireless stations including said wireless station through which said mobile communication terminal device is making wireless communication, through said plurality of wireless interfaces, detects internal interference among said plurality of wireless interfaces, and cancels said internal interference by changing profiles for operating one of said plurality of wireless interfaces.   
     
     
         16 . The mobile wireless communication system as set forth in  claim 1 , wherein said mobile communication terminal device is comprised of a mobile phone. 
     
     
         17 . A method of carrying out handover in a mobile wireless communication system comprising: a network; a plurality of wireless stations connected in wireless communication to said network; and a mobile communication terminal device making communication, keeping a first wireless link comprising a pair of uplink and downlink with one of said wireless stations,
 said method comprising:   a first step of, by said mobile communication terminal device, starting, when it is determined that communication quality of said downlink is low, to establish a second wireless link with a new wireless station, changing at least one of profiles (UTP) for transmitting wireless signal in said uplink, and notifying a wireless station through which said mobile communication terminal device is making wireless communication of the changed profile(s); and   a second step of, by said wireless station, changing a profile or profiles (URP) for receiving wireless signal in uplink, corresponding to the changed profile(s) (UTP) for transmitting wireless signal, in said uplink, received from said mobile communication terminal device.   
     
     
         18 . The method as set forth in  claim 17 , further comprising:
 a third step of, by said wireless station, changing at least one of profiles (DTP) for transmitting wireless signal in said downlink, and notifying said mobile communication terminal device of the changed profile(s) (DTP) for transmitting wireless signal in said downlink; and   a fourth step of, by said mobile communication terminal device, changing a profile or profiles (DRP) for receiving wireless signal in downlink, corresponding to the changed profile(s) (DTP) for transmitting wireless signal in said downlink, received from said wireless station.   
     
     
         19 . The method as set forth in  claim 17 , wherein in said first step, said mobile communication terminal device determines that the communication quality of said downlink is low when a strength of an electric field for receiving wireless signal in said downlink is equal to or smaller than a predetermined strength. 
     
     
         20 . The method as set forth in  claim 17 , wherein in said first step, said mobile communication terminal device determines that the communication quality of said downlink is low when a number of packet collisions exceeds a predetermined threshold. 
     
     
         21 . The method as set forth in  claim 17 , wherein in said first step, said mobile communication terminal device determines that the communication quality of said downlink is low when propagation delay of packets exceeds a predetermined threshold. 
     
     
         22 . The method as set forth in  claim 17 , wherein said wireless station is comprised of an access point having a WLAN (Wireless Local Area Network) function. 
     
     
         23 . The method as set forth in  claim 17 , wherein at least one of profiles (UTP) for transmitting wireless signal in said uplink is changed in said first step, based on a strength of an electric field for receiving wireless signal, an electric power for transmitting wireless signal, and an error rate. 
     
     
         24 . The method as set forth in  claim 23 , wherein at least one of profiles (UTP) for transmitting wireless signal in said uplink is modulation. 
     
     
         25 . The method as set forth in  claim 23 , wherein at least one of profiles (UTP) for transmitting wireless signal in said uplink is a coding rate. 
     
     
         26 . The method as set forth in  claim 23 , wherein said first wireless link is established in accordance with OFDMA (Orthogonal Frequency Division Multiple Access), and at least one of profiles (UTP) for transmitting wireless signal in said uplink is a number of sub-channels in said OFDMA. 
     
     
         27 . The method as set forth in  claim 18 , wherein said wireless station, on receipt of notification that a profile or profiles for transmitting wireless signal in said uplink has(have) been changed, from said mobile communication terminal device, changes in said third step at least one of profiles (DTP) for transmitting wireless signal in said downlink, based on a strength of an electric field for receiving wireless signal, an electric power for transmitting wireless signal, and an error rate. 
     
     
         28 . The method as set forth in  claim 27 , wherein at least one of profiles (DTP) for transmitting wireless signal in said downlink is modulation. 
     
     
         29 . The method as set forth in  claim 27 , wherein at least one of profiles (DTP) for transmitting wireless signal in said downlink is a coding rate. 
     
     
         30 . The method as set forth in  claim 27 , wherein said first wireless link is established in accordance with OFDMA (Orthogonal Frequency Division Multiple Access), and at least one of profiles (DTP) for transmitting wireless signal in said downlink is a number of sub-channels in said OFDMA. 
     
     
         31 . The method as set forth in  claim 17 , wherein said mobile communication terminal device includes a plurality of wireless interfaces different from each other with respect to a communication system,
 said method further includes a step of, by said mobile communication terminal device, simultaneously establishing a plurality of wireless links with the plurality of wireless stations including said wireless station through which said mobile communication terminal device is making wireless communication, through said plurality of wireless interfaces, detecting internal interference among said plurality of wireless interfaces, and canceling said internal interference by changing profiles for operating one of said plurality of wireless interfaces.   
     
     
         32 . A wireless station to be used in a mobile wireless communication system comprising: a network; a plurality of wireless stations connected in wireless communication to said network; and a mobile communication terminal device making communication, keeping a first wireless link comprising a pair of uplink and downlink with one of said wireless stations,
 the wireless station comprising:   a first unit that receives, from said mobile communication terminal device, at least one of profiles (UTP) for said mobile communication terminal device transmitting wireless signal in said uplink, the at least one of the profiles being changed by said mobile communication terminal device when said mobile communication terminal device determines that communication quality of said downlink is low and starts to establish a second wireless link with a new wireless station; and   a second unit that changes a profile or profiles (URP) for receiving wireless signal in uplink, corresponding to the changed profile(s) (UTP) for transmitting wireless signal in said uplink, received from said mobile communication terminal device.   
     
     
         33 . The wireless station as set forth in  claim 32 , further comprising:
 a third unit that changes at least one of profiles (DTP) for transmitting wireless signal in said downlink, and notifies said mobile communication terminal device of the changed profile(s) (DTP) for transmitting wireless signal in said downlink.   
     
     
         34 . The wireless station as set forth in  claim 32 , wherein said wireless station is comprised of an access point having a WLAN (Wireless Local Area Network) function. 
     
     
         35 . The wireless station as set forth in  claim 33 , wherein the third unit changes, on receipt of notification that a profile or profiles for transmitting wireless signal in said uplink has(have) been changed, from said mobile communication terminal device, at least one of profiles (DTP) for transmitting wireless signal in said downlink, based on a strength of an electric field for receiving wireless signal, an electric power for transmitting wireless signal, and an error rate. 
     
     
         36 . The wireless station as set forth in  claim 35 , wherein at least one of profiles (DTP) for transmitting wireless signal in said downlink is modulation. 
     
     
         37 . The wireless station as set forth in  claim 35 , wherein at least one of profiles (DTP) for transmitting wireless signal in said downlink is a coding rate. 
     
     
         38 . The wireless station as set forth in  claim 35 , wherein said first wireless link is established in accordance with OFDMA (Orthogonal Frequency Division Multiple Access), and at least one of profiles (DTP) for transmitting wireless signal in said downlink is a number of sub-channels in said OFDMA. 
     
     
         39 . A mobile communication terminal device in a mobile wireless communication system comprising: a network; a plurality of wireless stations connected in wireless communication to said network; and said mobile communication terminal device,
 said mobile communication terminal device making communication, keeping a first wireless link comprising a pair of uplink and downlink with one of said wireless stations,   said mobile communication terminal device comprising:   a first unit that starts, when it is determined that communication quality of said downlink is low, to establish a second wireless link with a new wireless station, and changes at least one of profiles (UTP) for transmitting wireless signal in said uplink; and   a second unit that notifies a wireless station through which said mobile communication terminal device is making wireless communication of the changed profile(s).   
     
     
         40 . The mobile communication terminal device as set forth in  claim 39 , further comprising:
 a third unit that receives, when said wireless station changes a profile or profiles (URP) for receiving wireless signal in uplink, corresponding to the changed profile(s) (UTP) for transmitting wireless signal in said uplink, received from said mobile communication terminal device, and changes at least one of profiles (DTP) for transmitting wireless signal in said downlink, the changed profile(s) (DTP) for transmitting wireless signal in said downlink; and   a fourth unit that changes a profile or profiles (DRP) for receiving wireless signal in downlink, corresponding to the changed profile(s) for transmitting wireless signal in said downlink, received from said wireless station.   
     
     
         41 . The mobile communication terminal device as set forth in  claim 39 , wherein the first unit determines that the communication quality of said downlink is low when a strength of an electric field for receiving wireless signal in said downlink is equal to or smaller than a predetermined strength. 
     
     
         42 . The mobile communication terminal device as set forth in  claim 39 , wherein the first unit determines that the communication quality of said downlink is low when a number of packet collisions exceeds a predetermined threshold. 
     
     
         43 . The mobile communication terminal device as set forth in  claim 39 , wherein the first unit determines that the communication quality of said downlink is low when propagation delay of packets exceeds a predetermined threshold. 
     
     
         44 . The mobile communication terminal device as set forth in  claim 39 , wherein the first unit changes at least one of profiles (UTP) for transmitting wireless signal in said uplink, based on a strength of an electric field for receiving wireless signal, an electric power for transmitting wireless signal, and an error rate. 
     
     
         45 . The mobile communication terminal device as set forth in  claim 44 , wherein at least one of profiles (UTP) for transmitting wireless signal in said uplink is modulation. 
     
     
         46 . The mobile communication terminal device as set forth in  claim 44 , wherein at least one of profiles (UTP) for transmitting wireless signal in said uplink is a coding rate. 
     
     
         47 . The mobile communication terminal device as set forth in  claim 39 , including:
 a plurality of wireless interfaces different from each other with respect to a communication system; and   a unit that simultaneously establishes a plurality of wireless links with the plurality of wireless stations including said wireless station through which said mobile communication terminal device is making wireless communication, through said plurality of wireless interfaces, detects internal interference among said plurality of wireless interfaces, and cancels said internal interference by changing profiles for operating one of said plurality of wireless interfaces.   
     
     
         48 . The mobile communication terminal device as set forth in  claim 39 , wherein said mobile communication terminal device is comprised of a mobile phone. 
     
     
         49 . A non-transitory computer-readable storage medium storing therein a program for causing a computer mounted in a wireless station to carry out a method of carrying out handover in a mobile wireless communication system comprising: a network; a plurality of wireless stations connected in wireless communication to said network; and a mobile communication terminal device making communication, keeping a first wireless link comprising a pair of uplink and downlink with one of said wireless stations,
 wherein the program causes said computer to execute:   a step of receiving, from said mobile communication terminal device, at least one of profiles (UTP) for said mobile communication terminal device transmitting wireless signal in said uplink, the at least one of the profiles being changed by said mobile communication terminal device when said mobile communication terminal device determines that communication quality of said downlink is low and starts to establish a second wireless link with a new wireless station; and   a step of changing a profile or profiles (URP) for receiving wireless signal in uplink, corresponding to the changed profile(s) (UTP) for transmitting wireless signal in said uplink, received from said mobile communication terminal device.   
     
     
         50 . A non-transitory computer-readable storage medium storing therein a program for causing a computer mounted in a mobile communication terminal device to carry out a method of carrying out handover in a mobile wireless communication system comprising: a network; a plurality of wireless stations connected in wireless communication to said network; and a mobile communication terminal device making communication, keeping a first wireless link comprising a pair of uplink and downlink with one of said wireless stations,
 wherein the program causes said computer to execute:   a step of starting, when it is determined that communication quality of said downlink is low, to establish a second wireless link with a new wireless station, and changing at least one of profiles (UTP) for transmitting wireless signal in said uplink; and   a step of notifying a wireless station through which said mobile communication terminal device is making wireless communication of the changed profile(s).