Wireless telecommunication system including at least a base station intended to communicate with terminals

• US 20070019667A1
• Filed: 07/19/2006
• Published: 01/25/2007
• Est. Priority Date: 07/21/2005
• Status: Active Grant

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Brunel, Loic, Mottier, David
• Granted Patent: US 7,801,090 B2
• Time in Patent Office: Days
• US Class Current: 370/458
• CPC Class Codes: H04B 7/2643 using time-division multiple access [TDMA] H04B7/2615, H04B7/2618 take precedence

Abstract

The present invention concerns a wireless telecommunication system including at least a base station intended to communicate with terminals over bidirectional communication channels, each channel supporting frames being divided into downlink timeslots and uplink timeslots, each downlink timeslot including a number of symbols intended to be transmitted to at least a terminal, a terminal after having received all the symbols included in a downlink timeslot followed by an uplink timeslot transmits other symbols over said uplink timeslot with a time delay depending on the distance between said terminal and said base station so that the so transmitted symbols are received by said base station at a time separated from the end of the transmission by the base station of the downlink timeslot by a predefined guard period constant whatever said distance. According to the invention, the base station comprises means for transmitting at least a supplementary downlink symbol during the guard period to terminals that can receive said at least supplementary downlink symbol during the time delays thereof and/or means for receiving during the guard period at least a supplementary uplink symbol from the terminals that can transmit said at least supplementary uplink symbols during the time delays thereof.

Claims

1. Wireless telecommunication system including at least a base station intended to communicate with terminals over bidirectional communication channels, each channel supporting frames being divided into downlink timeslots and uplink timeslots, each downlink timeslot including a number of symbols intended to be transmitted to at least a terminal, a terminal after having received all the symbols included in a downlink timeslot followed by an uplink timeslot transmits other symbols over said uplink timeslot with a time delay depending on the distance between said terminal and said base station so that the so transmitted symbols are received by said base station at a time separated from the end of the transmission by the base station of the downlink timeslot by a predefined guard period constant whatever said distance, characterized in that the base station comprises means for transmitting at least a supplementary downlink symbol during the guard period to terminals that can receive said at least supplementary downlink symbol during the time delays thereof and/or means for receiving during the guard period at least a supplementary uplink symbol from the terminals that can transmit said at least supplementary uplink symbols during the time delays thereof.

2. Wireless telecommunication system according to claim 1, characterized in that it comprises

means for determining the time delay of each terminal connected thereto,

means for allowing a base station to transmit to a terminal at distance d from a base station and the time delay of which is comprised between the duration of a number n_d1 of downlink symbols and the duration of a number n_d1 +1 of downlink symbols, respectively plus the time RTS of switching from the reception mode into the transmission mode, at most n_d1 supplementary downlink symbols, and

means for allowing said terminal to receive and process said n_d1 supplementary downlink symbols.

3. Wireless telecommunication system according to claim 1 or 2, characterized in that it comprises

means for determining the time delay of each terminal connected thereto,

means for allowing a terminal at distance d from the base station and the time delay of which is comprised between the duration of a number n_u1 of uplink symbols and the duration of a number n_u1+1 of uplink symbols, respectively plus the time RTS of switching from the reception mode into the transmission mode, to transmit at most n_u1 supplementary uplink symbols,

means for allowing the base station to receive and process said at most n_u1 supplementary uplink symbols.

4. Wireless telecommunication system according to claim 2 or 3, characterized in that the means for determining the time delay of a terminal at distance d from a base station includes means for subtracting to the value of the guard period the value of the round trip delay RTD(d) for that terminal.

5. Wireless telecommunication system according to claim 4, characterized in that the value of the guard period is given by the value of the round trip delay RTD(dref) for a terminal that is at a predetermined reference distance dref from the considered base station plus the time RTS of switching from the reception mode into the transmission mode.

6. Wireless telecommunication system according to one of the preceding claims, characterized in that as long as the time delay for a terminal is not determined, no information is included within any supplementary symbol.

7. Wireless telecommunication system according to one of preceding claims, characterized in that as long as the time delay for a terminal is not determined, the time delay for that terminal is considered as to be equal to the guard period.

8. Wireless telecommunication system according to one of the preceding claims, characterized in that it comprises means for informing each terminal connected thereto about the time delay it has to apply.

9. Wireless telecommunication system according to one of the preceding claims 1 to 8, characterized in that said base station uses modulation, coding and/or multiplexing schemes for the supplementary symbols that are different from those that it uses for the symbols of the reference time slots, said base station transmitting specific control information to the terminals that can receive that supplementary symbols for said terminals to detect, decode and de-multiplex said supplementary symbols.

10. Wireless telecommunication system according to claim 9, characterized in that the base station includes the specific control information related to a supplementary symbol within this supplementary symbol.

20. Terminal of a wireless telecommunication system said system being according to claims 1 to 10, characterized in that it comprises means for receiving and processing supplementary downlink symbols during the time delay thereof.

21. Terminal of a wireless telecommunication system according to claim 20, characterized in that it comprises means for determining from the value of the time delay it has to apply, the number n_d1 of downlink supplementary symbols it has to receive and process.

22. Terminal of a wireless telecommunication system, said system being according to claims 1 to 10, characterized in that it comprises means for transmitting supplementary uplink symbols during its time delay thereof.

23. Terminal of a wireless telecommunication system according to claim 22, characterized in that it comprises means for determining from the value of the time delay it has to apply, the number n_u1 of uplink supplementary symbols it has to transmit during said time delay period.

24. Terminal according to one of preceding claims 20 to 23, characterized in that as long as the time delay for a terminal is not determined, the time delay for that terminal is considered as to be equal to the guard period.

11. Base station of a wireless telecommunication system, said base station being intended to communicate with terminals over bidirectional communication channels, each channel supporting frames being divided into downlink time slots and uplink time slots, each downlink time slot including a number of symbols intended to be transmitted to at least a terminal, characterized in that said base station comprises

means for determining the time delay of each terminal connected thereto, said time delay being such that any terminal after having received all the symbols included in a downlink timeslot followed by an uplink timeslot transmits other symbols over said uplink timeslot with said time delay so that the transmitted symbols are received by said base station at a time separated from the end of the transmission by the base station of the downlink timeslot by a predefined guard period constant whatever said distance,

means for transmitting at least a supplementary downlink symbol during the guard period to terminals that can receive said at least supplementary downlink symbol during the time delays thereof and/or means for receiving during the guard period at least a supplementary uplink symbol from terminals that can transmit said at least supplementary symbol during the time delays thereof.

12. Base station according to claim 11, characterized in that said base station BTS comprises means for transmitting to a terminal at distance d from a base station and the time delay of which is comprised between the duration of a number n_d1 of downlink symbols and the duration of a number n_d1+1 of downlink symbols, respectively plus the time RTS of switching from the reception mode into the transmission mode, at most n_d1 supplementary downlink symbols.

13. Base station according to claim 11 or 12, characterized in that said base station BTS comprises means for receiving from a terminal at distance d from the base station and the time delay of which is comprised between the duration of a number n_u1 of uplink symbols and the duration of a number n_u1+1 of uplink symbols, respectively plus the time RTS of switching from the reception mode into the transmission mode, at most n_u1 supplementary uplink symbols.

14. Base station according to claim 12 or 13, characterized in that the means for determining the time delay of a terminal at distance d from a base station includes means for subtracting to the value of the guard period the value of the round trip delay RTD(d) for that terminal.

15. Base station according to claim 14, characterized in that the value of the guard period is given by the value of the round trip delay RTD(dref) for a terminal that is at a predetermined reference distance dref from the considered base station plus the switching time.

16. Base station according to one of the preceding claims 11 to 15, characterized in that as long as the time delay for a terminal is not determined, it includes no information within any downlink supplementary symbol.

17. Base station according to one of the preceding claims 11 to 16, characterized in that it comprises means for informing each terminal connected thereto about the time delay it has to apply.

18. Base station according to one of the preceding claims 11 to 17, characterized in that it uses modulation, coding and/or multiplexing schemes for the supplementary symbols that are different from those that it uses for the symbols of the reference time slots, said base station transmitting specific control information to the terminals that can receive that supplementary symbols for said terminals to detect, decode and de-multiplex said supplementary symbols.

19. Base station according to claim 18, characterized in that it includes the specific control information related to a supplementary symbol within this supplementary symbol.

25. Transmission method in a wireless telecommunication system including at least a base station intended to communicate with terminals over bidirectional communication channels, each channel supporting frames being divided into downlink timeslots and uplink timeslots, each downlink timeslot including a number of symbols intended to be transmitted to at least a terminal,

said method including the steps of

transmitting from the base station to terminals symbols included in a downlink timeslot,

receiving by each terminal the symbols included in said downlink timeslot,

transmitting by each terminal other symbols over a subsequent uplink timeslot with a time delay depending on the distance between said terminal and said base station so that the so transmitted symbols are received by said base station at a time separated from the end of the transmission by the base station of the downlink timeslot by a predefined guard period constant whatever said distance,

characterized in that it includes a step of transmitting by the base station at least a supplementary downlink symbol during the guard period to terminals that can receive said at least supplementary downlink symbol during the time delays thereof and/or a step of receiving by said base station during the guard period at least a supplementary uplink symbol from terminals that can transmit said at least supplementary symbol during the time delays thereof.

26. Transmission method according to claim 25, characterized in that it includes the steps of

determining the time delay of each terminal connected to the base station,

allowing said base station to transmit to a terminal at distance d from a base station and the time delay of which is comprised between the duration of a number n_d1 of downlink symbols and the duration of a number n_d1+1 of downlink symbols, respectively plus the time RTS of switching from the reception mode into the transmission mode, at most n_d1 supplementary downlink symbols, and

allowing said terminal to receive and process said n_d1 supplementary symbols.

27. Transmission method according to claim 25 or 26, characterized in that it includes the steps of

determining the time delay of each terminal connected to the base station,

allowing a terminal at distance d from the base station and the time delay of which is comprised between the duration of a number n_u1 of uplink symbols and the duration of a number n_u1 +1 of uplink symbols, respectively plus the time RTS of switching from the reception mode into the transmission mode, to transmit at most n_u1 supplementary uplink symbols, and

allowing the base station to receive said at most n_u1 supplementary uplink symbols.

28. Transmission method according to claim 26 or 27, characterized in that the step of determining the time delay of a terminal at distance d from a base station includes a step of subtracting to the value of the guard period the value of the round trip delay RTD(d) for that terminal.

29. Transmission method according to claim 28, characterized in that the value of the guard period is given by the value of the round trip delay RTD(dref) for a terminal that is at a predetermined reference distance dref from the considered base station plus the time RTS of switching from the reception mode into the transmission mode.

30. Transmission method according to one of the preceding claims 25 to 29, characterized in that as long as the time delay for a terminal is not determined, no information is included within any supplementary symbol.

31. Transmission method according to one of the preceding claims 25 to 30, characterized in that it comprises a step for informing each terminal connected thereto about the time delay it has to apply.

32. Transmission method according to claim 31, characterized in that as long as the time delay for a terminal is not determined, the time delay for that terminal is considered as to be equal to the guard period.

33. Transmission method according to one of the preceding claims 25 to 32, characterized in that it includes a step of using modulation, coding and/or multiplexing schemes for the supplementary symbols that are different from those used for the symbols of the reference time slots, said base station transmitting specific control information to the terminals that can receive that supplementary symbols for said terminals to detect, decode and to de-multiplex said supplementary symbols.

34. Transmission method according to claim 33, characterized in that the specific control information related to a supplementary symbol is included within this supplementary symbol.