Cellular wireless communications system and base station

• US 6,021,125 A
• Filed: 10/08/1998
• Issued: 02/01/2000
• Est. Priority Date: 10/16/1997
• Status: Expired due to Fees

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Sakoda, Kazuyuki, Suzuki, Mitsuhiro, Yamaura, Tomoya
• Primary Examiner(s): Ton, Dang
• Assistant Examiner(s): Sam, Phirin
• Application Number:
  US09/168,701
• Time in Patent Office: 481 Days
• Field of Search: 370/345, 370/314, 370/310, 370/328, 370/329, 370/330, 370/331, 370/332, 370/333, 370/334, 370/336, 370/337, 370/341, 370/343, 370/344, 370/347, 370/349, 370/380, 370/436 , 370/437, 370/442, 455/405, 455/421, 455/422, 455/434, 455/436, 455/439, 455/440, 455/442, 455/447, 455/450, 455/452, 455/507, 455/509, 455/513, 455/522, 455/524, 455/525
• US Class Current: 370/345
• CPC Class Codes: H04W 36/08 Reselecting an access point
• CPC Class Codes: H04W 36/18 for allowing seamless reselection, e.g. soft reselection
• CPC Class Codes: H04W 36/304 due to measured or perceived resources with higher communication quality

Abstract

A cellular wireless communication system for further improving the quality of communications. The base station (BS11) notifies the communication channel which the mobile station (MS10) is using, to the base stations (BS12, BS13) having the lower pathloss than the own station, the base stations receive said communication channel and transmit the reception signals (S2, S3) to the connection switching station (11), and the connection switching station combines respective reception signals (S1-S3) to be transmitted so as to restore the data transmitted from the mobile station, and thereby the reception signal received at the base station having the satisfactory receiving condition can be combined and the diversity reception using the whole system can be conducted, so that the quality of communications from the mobile station to the base station can be easily improved.

Claims

1. A cellular wireless communication system having mobile stations, base stations and connection switching stations for controlling said base stations, and for communicating between said mobile stations and said base stations by time division multiplexing connections, said cellular wireless communication system comprising:

a mobile station;

a first base station configured to communicate with said mobile station over a communication channel;

at least one other base station, wherein said mobile station, during communication with said first base station, is configured to receive a plurality of control channels from said first base station and said at least one other base station to measure a plurality of path losses therebetween, and is further configured to transmit a plurality of path loss information showing the measured plurality of path losses to said first base station; and

a connection switching station, wherein said first base station is configured to transmit a first reception signal received from said mobile station to said connection switching station, to determine that said at least one other base station has a smaller path loss than said first base station based on said plurality of path loss information, and in accordance therewith to indicate said communication channel to said at least one other base station,

wherein said at least one other base station is configured to receive the indicated communication channel and to measure a signal-to-interference wave power ratio thereof, and when the measured signal-to-interference wave power ratio is larger than a first threshold value, to transmit, to said connection switching station, a second reception signal received on said communication channel from said mobile station, and

wherein said connection switching station is configured to combine said first reception signal and said second reception signal into a composite reception signal, to perform decoding processing to said composite reception signal, and to output the decoded composite reception signal.

2. The cellular wireless communication system according to claim 1, wherein:

when communicating between said first base station and said mobile station, frequency hopping is conducted in order to sequentially switch a frequency used.

3. The cellular wireless communication system according to claim 1, wherein:

said communication channel is composed of multiple sub-carriers, and multi-carrier communication is conducted between said first base station and said mobile station.

4. The cellular wireless communication system according to claim 1, wherein:

said at least one other base station is configured to terminate reception of said communication channel when, during a predetermined period of time, a second ratio is more than a second threshold value, wherein said second ratio is based on the measured signal-to-interference wave power ratio and said first threshold value when the measured signal-to-interference wave power ratio does not exceed said first threshold value.

5. A cellular wireless communication system having mobile stations, base stations and connection switching stations for controlling said base stations, and for communicating between said mobile stations and said base stations by time division multiplexing connections, said cellular wireless communication system comprising:

a mobile station;

a first base station configured to communicate with said mobile station over a communication channel;

at least one other base station, wherein said mobile station, during communication with said first base station, is configured to receive a plurality of control channels from said first base station and said at least one other base station to measure a plurality of path losses therebetween, and is further configured to transmit a plurality of path loss information showing the measured plurality of path losses to said first base station; and

a connection switching station, wherein said first base station is configured to transmit a first reception signal received from said mobile station to said connection switching station, to determine that said at least one other base station has a smaller path loss than said first base station based on said plurality of path loss information, and in accordance therewith to indicate said communication channel to said at least one other base station,

wherein said at least one other base station is configured to receive the indicated communication channel and to measure a signal-to-interference wave power ratio thereof, and when the measured signal-to-interference wave power ratio is larger than a first threshold value, to transmit, to said connection switching station, a second reception signal received on said communication channel from said mobile station,

wherein said connection switching station is configured to combine said first reception signal and said second reception signal into a composite reception signal, to perform decoding processing to said composite reception signal, and to output the decoded composite reception signal, and

wherein said at least one other base station is configured to terminate reception of said communication channel when, during a predetermined period of time, a second ratio is more than a second threshold value, wherein said second ratio is based on the measured signal-to-interference wave power ratio and said first threshold value when the measured signal-to-interference wave power ratio does not exceed said first threshold value.

6. A cellular wireless communication system having mobile stations, base stations and connection switching stations for controlling said base stations, and for communicating between said mobile stations and said base stations by time division multiplexing connections, said cellular wireless communication system comprising:

a mobile station;

a first base station configured to communicate with said mobile station over a communication channel;

at least one other base station, wherein said mobile station, during communication with said first base station, is configured to receive a plurality of control channels from said first base station and said at least one other base station to measure a plurality of path losses therebetween, and is further configured to transmit a plurality of path loss information showing the measured plurality of path losses to said first base station; and

a connection switching station, wherein said first base station is configured to transmit a first reception signal received from said mobile station to said connection switching station, and to identify to said at least one other base station said communication channel when it is determined that said mobile station should be handed off to said at least one other base station based on at least one of said plurality of path loss information and a value of transmission power to said mobile station,

wherein said at least one other base station is configured to receive the identified communication channel and to measure a reception power thereof, and when the measured reception power is more than a first threshold value, to transmit reply information indicating said reception power to said first base station,

wherein said first base station is further configured to identify said at least one other base station having a largest reception power according to said reply information as a destination of handoff, and in accordance therewith to hand off said mobile station to said at least one other base station, and

wherein said at least one other base station, when the measured reception power does not exceed said first threshold value, is configured to continuously measure said reception power during a fixed period of time, and when said reception power exceeds said first threshold value during said fixed period of time, to identify said reply information to said first base station, and when said reception power does not exceed the first threshold value during said fixed period of time, to terminate reception of said communication channel.

7. A cellular wireless communication system having mobile stations, base stations and connection switching stations for controlling said base stations, and for communicating between said mobile stations and said base stations by time division multiplexing connections, said cellular wireless communication system comprising:

a mobile station;

a first base station configured to communicate with said mobile station over a communication channel;

at least one other base station, wherein said mobile station, during communication with said first base station, is configured to receive a plurality of control channels from said first base station and said at least one other base station to measure a plurality of path losses therebetween, and is further configured to transmit a plurality of path loss information showing the measured plurality of path losses to said first base station; and

a connection switching station, wherein said first base station is configured to transmit a first reception signal received from said mobile station to said connection switching station, and to identify to said at least one other base station said communication channel when it is determined that said mobile station should be handed off to said at least one other base station based on at least one of said plurality of path loss information and a value of transmission power to said mobile station,

wherein said at least one other base station is configured to receive the identified communication channel and to measure a reception power thereof, and when the measured reception power is more than a first threshold value, to transmit reply information indicating said reception power to said first base station,

wherein said first base station is further configured to identify said at least one other base station having a largest reception power according to said reply information as a destination of handoff, and in accordance therewith to hand off said mobile station to said at least one other base station,

wherein said first base station, after conducting handoff of the mobile station to said at least one other base station, is further configured to receive said communication channel, and when a signal-to-interference wave power ratio of said communication channel exceeds a second threshold value, to transmit a second reception signal to said connection switching station, and

wherein said connection switching station is further configured to conduct decoding processing to a composite reception signal obtained by combining said first reception signal and said second reception signal, so as to decode data transmitted from said mobile station.

8. The cellular wireless communication system according to claim 7, wherein:

said first base station, during a predetermined period of time, in case where a second ratio is more than a third threshold value, is configured to terminate reception of said communication channel, wherein said second ratio is based on the measured signal-to-interference wave power ratio and said second threshold value when the measured signal-to-interference wave power ratio does not exceed said second threshold value.

9. A cellular wireless communication system having mobile stations, base stations and connection switching stations for controlling said base stations, and for communicating between said mobile stations and said base stations by time division multiplexing connections, said cellular wireless communication system comprising:

a mobile station;

a first base station configured to communicate with said mobile station over a communication channel;

at least one other base station, wherein said mobile station, during communication with said first base station, is configured to receive a plurality of control channels from said first base station and said at least one other base station to measure a plurality of path losses therebetween, and is further configured to transmit a plurality of path loss information showing the measured plurality of path losses to said first base station; and

a connection switching station, wherein said first base station is configured to transmit a first reception signal received from said mobile station to said connection switching station, and to identify to said at least one other base station said communication channel when it is determined that said mobile station should be handed off to said at least one other base station based on at least one of said plurality of path loss information and a value of transmission power to said mobile station,

wherein said at least one other base station is configured to receive the identified communication channel and to measure a reception power thereof, and when the measured reception power is more than a first threshold value, to transmit reply information indicating said reception power to said first base station,

wherein said first base station is further configured to identify said at least one other base station having a largest reception power according to said reply information as a destination of handoff, and in accordance therewith to hand off said mobile station to said at least one other base station,

wherein when handoff is repeated between said first base station and said at least one other base station in a short period of time, said first threshold value is changed.

10. The cellular wireless communication system according to claim 9, wherein:

when said first threshold value is changed, a transmission speed used in communication with said mobile station is decreased.

11. A cellular wireless communication system comprising:

a connection switching station; and

at least one other base station,

wherein said connection switching station is configured to receive a plurality of signals from a first base station and said at least one other base station, to determine whether said at least one other base station has a smaller path loss than a path loss of said first base station based on a plurality of path loss information, and in accordance therewith to identify a communication channel, which a mobile station is using to communicate with said first base station, to said at least one other base station, to combine a first reception signal from said first base station and a second reception signal from said at least one other base station into a composite reception signal, to perform decoding processing to said composite reception signal, and to output the decoded composite reception signal,

wherein said at least one other base station is configured to receive the identified communication channel and to measure a signal-to-interference wave power ratio thereof, and when the measured signal-to-interference wave power ratio is larger than a first threshold value, to transmit, to said connection switching station, said second reception signal received on said communication channel.

12. A cellular wireless communication method for controlling mobile stations and base stations by connection switching stations, and for communicating between said mobile stations and said base stations by time division multiplexing connections, said cellular wireless communication method comprising the steps of:

communicating between a first base station and a mobile station over a communication channel;

during communication with said first base station, receiving by said mobile station a plurality of control channels from said first base station and at least one other base station to measure a plurality of path losses therebetween, and transmitting a plurality of path loss information showing the measured plurality of path losses to said first base station;

transmitting by said first base station a first reception signal received from said mobile station to a connection switching station, determining by said first base station that said at least one other base station has a smaller path loss than said first station based on said plurality of path loss information, and in accordance therewith identifying said communication channel to said at least one other base station;

receiving by said at least one other base station the identified communication channel and measuring a signal-to-interference wave power ratio thereof, and when the measured signal-to-interference wave power ratio is larger than a first threshold value, transmitting to said connection switching station a second reception signal received on said communication channel from said mobile station; and

combining by said connection switching station said first reception signal and said second reception signal into a composite reception signal, conducting decoding processing to composite reception signal, and outputting the decoded composite reception signal.

13. The cellular wireless communication method according to claim 12, wherein:

when communicating between said first base station and said mobile station, frequency hopping is conducted in order to sequentially switch a frequency used.

14. The cellular wireless communication method according to claim 12, wherein:

said communication channel is composed of multiple sub-carriers, and multi-carrier communication is conducted between said first base station and said mobile station.

15. A cellular wireless communication method for controlling mobile stations and base stations by connection switching stations, and for communicating between said mobile stations and said base stations by time division multiplexing connections, said cellular wireless communication method comprising the steps of:

communicating between a first base station and a mobile station over a communication channel;

during communication with said first base station, receiving by said mobile station a plurality of control channels from said first base station and at least one other base station to measure a plurality of path losses therebetween, and transmitting a plurality of path loss information showing the measured plurality of path losses to said first base station;

transmitting by said first base station a first reception signal received from said mobile station to a connection switching station, determining by said first base station that said at least one other base station has a smaller path loss than said first station based on said plurality of path loss information, and in accordance therewith identifying said communication channel to said at least one other base station;

receiving by said at least one other base station the identified communication channel and measuring a signal-to-interference wave power ratio thereof, and when the measured signal-to-interference wave power ratio is larger than a first threshold value, transmitting to said connection switching station a second reception signal received on said communication channel from said mobile station;

combining by said connection switching station said first reception signal and said second reception signal into a composite reception signal, conducting decoding processing to signal, and outputting the decoded composite reception signal; and

terminating reception of said communication channel during a predetermined period of time when a second ratio is more than a second threshold value, wherein said second ratio is based on the measure signal-to-interference wave power ratio and said first threshold value, when the measured signal-to-interference power ratio does not exceed said first threshold value.

16. A cellular wireless communication method for controlling a cellular wireless communication system having mobile stations, base stations and connection switching stations for controlling said base stations, and for communicating between said mobile stations and said base stations by time division multiplexing connections, said cellular wireless communication method comprising the steps of:

communicating between a first base station and a mobile station over a communication channel;

receiving by said mobile station a plurality of control channels from said first base station and at least one other base station and measuring a plurality of path losses therebetween, and transmitting a plurality of path loss information showing the measured plurality of path losses to said first base station; and

transmitting by said first base station a first reception signal received from said mobile station to a connection switching station, and identifying to said at least one other base station said communication channel when it is determined that said mobile station should be handed off to said at least one other base station based on at least one of said plurality of path loss information and a value of transmission power to said mobile station;

receiving by said at least one other base station the identified communication channel and measuring a reception power thereof, and when the measured reception power is more than a first threshold value, transmitting reply information indicating said reception power to said first base station;

identifying by said first base station said at least one other base station having a largest reception power according to said reply information as a destination of handoff, and in accordance therewith handing off said mobile station to said at least one other base station;

when the measured reception power does not exceed said first threshold value, continuously measuring by said at least one other base station said reception power during a fixed period of time, and when said reception power exceeds said first threshold value during said fixed period of time, identifying by said at least one other base station said reply information to said first base station and when said reception power does not exceed the first threshold value during said fixed period of time, terminating by said at least one other base station reception of said communication channel.

17. The cellular wireless communication method for controlling a cellular wireless communication system having mobile stations, base stations and connection switching stations for controlling said base stations, and for communicating between said mobile stations and said base stations by time division multiplexing connections, said cellular wireless communication method comprising the steps of:

communicating between a first base station and a mobile station over a communication channel;

receiving by said mobile station a plurality of control channels from said first base station and at least one other base station and measuring a plurality of path losses therebetween, and transmitting a plurality of path loss information showing the measured plurality of path losses to said first base station; and

transmitting by said first base station a first reception signal received from said mobile station to a connection switching station, and identifying to said at least one other base station said communication channel when it is determined that said mobile station should be handed off to said at least one other base station based on at least one of said plurality of path loss information and a value of transmission power to said mobile station;

receiving by said at least one other base station the identified communication channel and measuring a reception power thereof, and when the measured reception power is more than a first threshold value, transmitting reply information indicating said reception power to said first base station;

identifying by said first base station said at least one other base station having a largest reception power according to said reply information as a destination of handoff, and in accordance therewith handing off said mobile station to said at least one other base station;

after conducting handoff of the mobile station to said at least one other base station, receiving by said first base station the communication channel, and when a signal-to-interference wave power ratio of said communication channel exceeds a second threshold value, transmitting a second reception signal to said connection switching station; and

conducting by said connection switching station decoding processing to a composite reception signal obtained by combining said first reception signal and said second reception signal, so as to decode data transmitted from said mobile station.

18. The cellular wireless communication method according to claim 17, wherein:

during a base predetermined period of time, when a second ratio is more than a third threshold value, terminating by said first base station reception of said communication channel, wherein said second ratio is based on the measured signal-to-interference wave power ratio and said second threshold value when the measured signal-to-interference wave power ratio does not exceed said second threshold value.

19. A cellular wireless communication method for controlling mobile stations and base stations by connection switching stations, and for communicating between said mobile stations and said base stations by time division multiplexing connections, said cellular wireless communication method comprising the steps of:

communicating between a first base station and a mobile station over a communication channel;

receiving a plurality of control channels by said mobile station, during communication with said first base station, from said first base station and at least one other base station, measuring a plurality of path losses therebetween, and transmitting by said mobile station a plurality of path loss information showing the measured plurality of path losses to said first base station;

transmitting by said first base station a first reception signal received from said mobile station to a connection switching station, and identifying to said at least one other base station said communication channel when it is determined that said mobile station should be handed off to said at least one other base station based on at least one of said plurality of path loss information and a value of transmission power to said mobile station;

receiving by said at least one other base station the identified communication channel and measuring a reception power thereof, and when the measured reception power is more than a first threshold value, transmitting reply information indicating said reception power to said first base station;

identifying by said first base station said at least one other base station having a largest reception power according to said reply information as a destination of handoff, and in accordance therewith handing off said mobile station to said at least one other base station; and

changing said first threshold value when handoff is repeated between said first base station and said at least one other base station in a short period of time.

20. The cellular wireless communication method according to claim 19, further comprising:

decreasing a transmission speed used in communication with said mobile station when said first threshold value is changed.

21. A cellular wireless communication method comprising the steps of:

receiving by a connection switching station a plurality of signals from a first base station and at least one other base station;

determining whether said at least one other base station has a smaller path loss than a path loss of said first base station based on a plurality of path loss information, and in accordance therewith identifying a communication channel, which a mobile station is using to communicate with said first base station, to said at least one other base station, combining a first reception signal from said first base station and a second reception signal from said at least one other base station into a composite reception signal, performing decoding processing to said composite reception signal, and outputting the decoded composite reception signal; and

receiving by said at least one other base station the identified communication channel and measuring a signal-to-interference wave power ratio thereof, and when the measured signal-to-interference wave power ratio is larger than a first threshold value, transmitting the second reception signal received on said communication channel to said connection switching station.