Communication systems

• US 8,213,356 B2
• Filed: 07/31/2007
• Issued: 07/03/2012
• Est. Priority Date: 10/02/2006
• Status: Expired due to Fees

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Hart, Michael John Beems, Zhou, Yuefeng, Vadgama, Sunil Keshavji
• Primary Examiner(s): Yao, Kwang B
• Assistant Examiner(s): Huq, Obaidul
• Application Number:
  US12/301,414
• Publication Number:
  US 20100002619A1
• Time in Patent Office: 1,799 Days
• Field of Search: 370/310, 370/310.1, 370/310.2, 370/315, 370/316, 370/326, 370/328, 370/229, 370/335, 370/342, 370/343, 370/329, 370/336, 370/431, 370/464, 370/474, 370/480, 370/498, 455/7, 455/15, 455/16
• US Class Current: 370/328
• CPC Class Codes: H04B 7/026 Co-operative diversity, e.g. using fixed or mobile stations as relays
• CPC Class Codes: H04B 7/155 Ground-based stations H04B7/204 takes precedence
• CPC Class Codes: H04L 1/1816 with retransmission of the same, encoded, message
• CPC Class Codes: H04L 1/1819 with retransmission of additional or different redundancy
• CPC Class Codes: H04L 1/1845 Combining techniques, e.g. code combining
• CPC Class Codes: H04L 2001/0097 Relays

Abstract

A downlink transmission method for use in a multi-hop communication system, the system comprising a base station (BS), a mobile station (MS) and one or more relay stations (RS), and the system providing two or more different communication paths extending between the base station and the mobile station, the base station being operable to transmit information indirectly to the mobile station along a series of links forming a first such communication path via one or more of said relays and also being operable to transmit information to the mobile station along one link or a series of links forming a second such communication path; the method comprising transmitting particular information from the base station along the first and second communication paths and combining the same particular information transmitted along the first and second communication paths in the mobile station.

Claims

1. A downlink transmission method for use in a multi-hop communication system, the system comprising a source apparatus, a destination apparatus and one or more intermediate apparatuses, and the system providing two or more different communication paths extending between said source apparatus and said destination apparatus, said source apparatus being operable to transmit information indirectly to the destination apparatus along a series of links forming a first such communication path via one or more of said intermediate apparatuses and also being operable to transmit information to said destination apparatus along one link forming a second such communication path, and the intermediate apparatus or each intermediate apparatus being operable to receive information from a previous apparatus along a path and to transmit the received information to a subsequent apparatus along a path;

the method comprising

transmitting particular information from the source apparatus along the first communication path via one or more of said intermediate apparatuses to the destination apparatus;

transmitting the same particular information from the source apparatus along the second communication path to the destination apparatus; and

combining the same particular information transmitted along the first and second communication paths in the destination apparatus, wherein the second communication path is a direct communication path and the same particular information is transmitted along the second path directly from said source apparatus to said destination apparatus.

2. The method according to claim 1, wherein the system further provides a third such communication path, said source apparatus being operable to transmit the same particular information indirectly to the destination apparatus along a series of links forming the third communication path via one or more of said intermediate apparatuses, the method further comprising

transmitting the same particular information from the source apparatus along the third communication path via each of these intermediate apparatuses to the destination apparatus;

combining the same particular information transmitted along the first, second and third communication paths in the destination apparatus; and

checking the combined information from the first, second and third communication paths for errors.

3. The method according to claim 1, wherein the same particular information is transmitted along both or all, as the case may be, of the said communication paths to said destination apparatus in a discrete time period for downlink transmission only, which is followed by a discrete time period for uplink transmission only;

and wherein the discrete time period for downlink transmission and the discrete time period for uplink transmission are preferably a downlink sub-frame and an uplink sub-frame respectively in a time-division-duplex communication system.

4. The method according to claim 1, further comprising, before transmission of said particular information, transmitting timing information to the destination apparatus indicating when the said particular information is to be transmitted along the said communication paths.

5. The method according to claim 1 further comprising checking the combined information from the first and second communication paths for errors and preferably further comprising transmitting an error indication if an error is found and/or transmitting a positive indication if no error is found.

6. The method according to claim 5, wherein the error indication includes a request for retransmission of the particular information, the method preferably further comprising, if an error indication is transmitted, re-transmitting the particular information along one or more of said communication paths and combining the re-transmission with the previously combined information.

7. The method according to claim 5, further comprising adding an error detection sequence to said particular information before transmission and using the error detection sequence in the destination apparatus to check for errors in the combined information, wherein the error detection sequence is preferably a Cyclic Redundancy Check (CRC).

8. The method according to claim 1, wherein, before said particular information is transmitted, it is encoded.

9. The method according to claim 8, wherein said particular information is encoded with the same encoding version for each said communication path or with a different encoding version for each said communication path.

10. The method according to claim 8, further including decoding the encoded information if no errors are detected.

11. The method according to claim 8, wherein the encoding is Hybrid Automatic Repeat Request (HARQ) packet encoding and the transmissions of the same information along both or all of the communication paths, as the case may be, are treated as transmission and re-transmission(s) according to HARQ.

12. The method according to claim 1, wherein said system is an Orthogonal Frequency Division Multiplexing (OFDM) or Orthogonal Frequency Division Multiple Access (OFDMA) system.

13. The method according to claim 1, wherein said source apparatus is a base station or a relay station;

wherein said destination apparatus is a user terminal or a relay station; and

wherein the intermediate apparatus or each said intermediate apparatus is a relay station.

14. A multi-hop wireless communication system, the system comprising:

a source apparatus, a destination apparatus and one or more intermediate apparatuses, and the system providing two or more different downlink communication paths extending between said source apparatus and said destination apparatus, said source apparatus being operable to transmit information indirectly to the destination apparatus along a series of links forming a first such communication path via one or more of said intermediate apparatuses and also being operable to transmit information to said destination apparatus directly from said source apparatus to said destination apparatus along one link forming a second such communication path, and the intermediate apparatus or each intermediate apparatus being operable to receive information from a previous apparatus along a path and to transmit the received information to a subsequent apparatus along a path;

a transmitter operable to transmit particular information from the source apparatus along the first communication path via one or more of said intermediate apparatuses to the destination apparatus, and to transmit the same particular information from the source apparatus along the second communication path to the destination apparatus; and

a soft buffer operable to combine the same particular information transmitted along the first and second communication paths in the destination apparatus.

15. A method in a destination apparatus of a multi-hop communication system, for improving reception reliability, the system comprising a source apparatus, the destination apparatus and one or more intermediate apparatuses, and the system providing two or more different downlink communication paths extending between said source apparatus and said destination apparatus, said source apparatus being operable to transmit information indirectly to the destination apparatus along a series of links forming a first such communication path via one or more of said intermediate apparatuses and also being operable to transmit information to said destination apparatus along one link forming a second such communication path, and the intermediate apparatus or each intermediate apparatus being operable to receive information from a previous apparatus along a path and to transmit the received information to a subsequent apparatus along a path;

the method comprising

receiving particular information transmitted from the source apparatus along the first communication path via one or more of said intermediate apparatuses;

receiving the same particular information transmitted from the source apparatus along the second communication path; and

combining the same particular information transmitted along the first and second communication paths;

wherein

the second communication path is a direct communication path and the same particular information is transmitted along the second path directly from said source apparatus to said destination apparatus.

16. A destination apparatus of a multi-hop communication system, the system comprising a source apparatus, the destination apparatus and one or more intermediate apparatuses, and the system providing two or more different downlink communication paths extending between said source apparatus and said destination apparatus, said source apparatus being operable to transmit information indirectly to the destination apparatus along a series of links forming a first such communication path via one or more of said intermediate apparatuses and also being operable to transmit information to said destination apparatus along one link forming a second such communication path, and the intermediate apparatus or each intermediate apparatus being operable to receive information from a previous apparatus along a path and to transmit the received information to a subsequent apparatus along a path;

the destination apparatus comprising

a receiver operable to receive particular information transmitted from the source apparatus along the first communication path via one or more of said intermediate apparatuses to the destination apparatus, and to receive the same particular information transmitted directly from the source apparatus to the destination apparatus along one link forming the second communication path; and

a soft buffer operable to combine the same particular information transmitted along the first and second communication paths in the destination apparatus.

17. A non-transitory computer-readable storage medium or a plurality of non-transitory computer-readable storage media storing a suite of computer programs which, when executed on computing devices of a multi-hop wireless communication system, causes the system to carry out a downlink transmission method, the system comprising a source apparatus, a destination apparatus and one or more intermediate apparatuses, and the system providing two or more different communication paths extending between said source apparatus and said destination apparatus, said source apparatus being operable to transmit information indirectly to the destination apparatus along a series of links forming a first such communication path via one or more of said intermediate apparatuses and also being operable to transmit information to said destination apparatus along one link forming a second such communication path, and the intermediate apparatus or each intermediate apparatus being operable to receive information from a previous apparatus along a path and to transmit the received information to a subsequent apparatus along a path;

the method comprising

transmitting particular information from the source apparatus along the first communication path via one or more of said intermediate apparatuses to the destination apparatus;

transmitting the same particular information from the source apparatus along the second communication path to the destination apparatus;

combining the same particular information transmitted along the first and second communication paths in the destination apparatus, wherein

the second communication path is a direct communication path and the same particular information is transmitted along the second path directly from said source apparatus to said destination apparatus.

18. A non-transitory computer-readable storage medium or a plurality of non-transitory computer-readable storage media storing a computer program which, when executed on a computing device of a destination apparatus in a communication system, causes the destination apparatus to carry out a method for improving reception reliability, the system comprising a source apparatus, the destination apparatus and one or more intermediate apparatuses, and the system providing two or more different downlink communication paths extending between said source apparatus and said destination apparatus, said source apparatus being operable to transmit information indirectly to the destination apparatus along a series of links forming a first such communication path via one or more of said intermediate apparatuses and also being operable to transmit information to said destination apparatus along one link forming a second such communication path, and the intermediate apparatus or each intermediate apparatus being operable to receive information from a previous apparatus along a path and to transmit the received information to a subsequent apparatus along a path;

the method comprising;

receiving particular information transmitted from the source apparatus along the first communication path via one or more of said intermediate;

receiving the same particular information transmitted from the source apparatus along the second communication path; and

combining the same particular information transmitted along the first and second communication paths, wherein

the second communication path is a direct communication path and the same particular information is transmitted along the second path directly from said source apparatus to said destination apparatus.