Framing for an adaptive modulation communication system

• US 7,197,022 B2
• Filed: 11/15/2001
• Issued: 03/27/2007
• Est. Priority Date: 11/15/2000
• Status: Active Grant

• Current Assignee: Ford Motor Company, Quarterhill Inc. (f/k/a Wi-LAN Inc.)
• Original Assignee: Quarterhill Inc. (f/k/a Wi-LAN Inc.)
• Inventors: Klein, Israel Jay, Chen, An, Stanwood, Kenneth L., Lin, George
• Primary Examiner(s): Nguyen; Chau
• Assistant Examiner(s): GREY, CHRISTOPHER P
• Application Number:
  US09/991,532
• Publication Number:
  US 20020118666A1
• Time in Patent Office: 1,958 Days
• Field of Search: 370/345, 370/347, 370/442, 370/509, 370/330
• US Class Current: 370/337
• CPC Class Codes: H04B 7/15557 Selecting relay station operation mode, e.g. between amplify and forward mode, decode and forward mode or FDD - and TDD mode
• CPC Class Codes: H04B 7/212 Time-division multiple access [TDMA]
• CPC Class Codes: H04B 7/2615 using hybrid frequency-time division multiple access [FDMA-TDMA]
• CPC Class Codes: H04B 7/2656 for structure of frame, burst
• CPC Class Codes: H04B 7/2681 Synchronisation of a mobile station with one base station
• CPC Class Codes: H04L 1/0003 by switching between different modulation schemes
• CPC Class Codes: H04L 1/0009 by adapting the channel coding H04L1/1812 takes precedence
• CPC Class Codes: H04L 5/16 Half-duplex systems; Simplex/duplex switching; Transmission of break signals non-automatically inverting the direction of transmission
• CPC Class Codes: H04W 56/0085 detecting a given structure in the signal
• CPC Class Codes: H04W 72/23 in the downlink direction of a wireless link, i.e. towards a terminal

Abstract

A system and method for mapping a combined frequency division duplexing (FDD) Time Division Multiplexing (TDM)/Time Division Multiple Access (TDMA) downlink subframe for use with half-duplex and full-duplex terminals in a communication system. Embodiments of the downlink subframe vary Forward Error Correction (FEC) types for a given modulation scheme as well as support the implementation of a smart antennae at a base station in the communication system. Embodiments of the system are also used in a TDD communication system to support the implementation of smart antennae. A scheduling algorithm allows TDM and TDMA portions of a downlink to efficiently co-exist in the same downlink subframe and simultaneously support full and half-duplex terminals. The algorithm further allows the TDM of multiple terminals in a TDMA burst to minimize the number of map entries in a downlink map. The algorithm limits the number of downlink map entries to not exceed 2n+1, where n is the number of DL PHY modes (modulation/FEC combinations) employed by the communication system.

Claims

1. A frequency division duplexing (FDD) wireless communication method for use by a base station, a first terminal, and a second terminal, wherein the base station transmits using a downlink subframe on a first channel and the first and second terminals transmit using an uplink subframe on a second channel, wherein the downlink subframe includes a broadcast preamble, a time division multiplex (TDM) portion, and a Time Division Multiple Access (TDMA) portion, and wherein the TDMA portion includes at least one modulation/forward error correction (PHY) mode with an associated preamble, both of which are intended for the second terminal, the method comprising:

transmitting a broadcast preamble from a base station to a first terminal and a second terminal during a downlink subframe on a first channel;

synchronizing the first terminal and the second terminal to the base station based on the broadcast preamble;

transmitting modulated data from the second terminal to the base station during an uplink subframe on a second channel;

transmitting modulated data from the base station to the first terminal during a TDM portion of the downlink subframe on the first channel after the first terminal is synchronized with the base station;

transmitting a preamble from the base station during a TDMA portion of the downlink subframe on the first channel, wherein the preamble is transmitted after the second terminal has transmitted its modulated data to the base station;

re-synchronizing the second terminal with the base station based on the preamble transmitted by the base station on the first channel;

transmitting modulated data from the base station to the second terminal during the TDMA portion of the downlink subframe on the first channel after the second terminal is re-synchronized with the base station, and

transmitting a broadcast downlink map during the downlink subframe from the base station which indicates when the TDM portion of the downlink subframe transitions to the TDMA portion of the downlink subframe.

2. The method of claim 1, wherein the broadcast downlink map includes at least one time indicator and an associated downlink interval usage code (DIUC), wherein the DIUC indicates the TDMA portion.

3. The method of claim 2, further comprising transmitting a broadcast uplink map during the downlink subframe by the base station which indicates when the second terminal is scheduled to transmit to the base station during the uplink subframe on a second channel.

4. The method of claim 3, wherein the broadcast downlink map identifies a beginning of the TDMA portion within the downlink subframe and the broadcast uplink map identifies when the second terminal is scheduled to transmit during a next uplink subframe.

5. The method of claim 3, wherein the downlink subframe and the uplink subframe have a combined duration of 0.5 milliseconds.

6. The method of claim 3, wherein the downlink subframe and the uplink subframe have a combined duration of 1 milliseconds.

7. The method of claim 3, wherein the downlink subframe and the uplink subframe have a combined duration of 2 milliseconds.

8. The method of claim 3, wherein the duration of the downlink subframe on the first channel and the duration of the uplink subframe on the second channel vary over time.

9. The method of claim 3, further comprising transmitting modulated data from the first terminal to the base station during the uplink subframe on the second channel.

10. The method of claim 9, wherein transmitting by the second terminal and transmitting by the first terminal are performed using different PHY modes.

11. The method of claim 9, wherein transmitting to the first terminal and transmitting to the second terminal, both by the base station, is performed using different PHY modes.

12. The method of claim 9, wherein transmissions during the uplink subframe and the downlink subframe are modulated using Quadrature Amplitude Modulation (QAM) symbols of adaptable modulation density.

13. The method of claim 9, wherein transmissions during the uplink subframe and the downlink subframe comprise Orthogonal Frequency Division Multiplexing (OFDM) symbols of adaptable modulation density.

14. The method of claim 10, wherein the first terminal and the second terminal use the same modulation type with different forward error correction types.

15. A frequency division duplexing (FDD) wireless communication method for use by a base station, a first terminal, and a second terminal, wherein the base station transmits using a downlink subframe on a first channel and the first and second terminals transmit using an uplink subframe on a second channel, whrerein the downlink subframe includes a broadcast preamble, a time division multiplex (TDM) portion, and a Time Division Multiple Access (TDMA) portion, and wherein the TDMA portion includes at least one modulation/forward error correction (PHY) mode with an associated preamble, both of which are intended for the second terminal, the method comprising:

transmitting a broadcast preamble from a base station to a first terminal and a second terminal during a downlink subframe on a first channel;

sychronizing the first terminal and the second terminal to the base station based on the broadcast preamble;

transmitting modulated data from the second terminal to the base station during an uplink subframe on a second channel;

transmitting modulated data from the base station to the first terminal during a TDM portion of the downlink subframe on the first channel after the first terminal is synchronized with the base station;

transmitting a preamble from the base station during a TDMA portion of the downlink subframe on the first channel, wherein the preamble is transmitted after the second terminal has transmitted its modulated data to the base station;

re-synchronizing the second terminal with the base station based on the preamble transmitted by the base station on the first channel, further comprising transmitting modulated data from the base station to the second terminal during the TDMA portion of the downlink subframe on the first channel after the second terminal is re-sychronized with the base station; and

wherein the first terminal operates in a full-duplex fashion and the second terminal operated in a half-duplex fashion.

16. A frequency division duplexing (FDD) wireless communication method for use by a base station, a first terminal, and a second terminal, wherein the base station transmit using a downlink subframe on a first channel and the first and second terminals transmit using an uplink subframe on a second channel, wherein the downlink subframe includes a broadcast preamble, a time division multiplex (TDM) portion, and a Time Division Multiple Access (TDMA) portion, and wherein the TDMA portion includes at least one modulation/forward error correction (PHY) mode with an associated preamble, both of which are intended for the second terminal, the method comprising:

transmitting a broadcast preamble from a base station to a first terminal and a second terminal during a downlink subframe on a first channel;

synchronizing the first terminal and the second terminal to the base station based on the broadcast preamble;

transmitting modulated data fron the second terminal to the base station during an uplink subframe on a second channel;

transmitting modulated data from the base station to the first terminal during a TDM portion of the downlink subframe on the first channel after the first terminal is synchronized with the base station;

transmitting a preamble from the base station during a TDMA portion of the downlink subframe on the first channel, wherein the preamble is transmitted after the second terminal has transmitted its modulated data to the base station;

re-synchronizing the second terminal with the base station based on the preamble transmitted by the base station on the first channel;

transmitting modulated data from the base station to the second terminal during the TDMA portion of the downlink subframe on the first channel after the second terminal is re-synchronized with the base station; and

wherein the first and second terminals operate in a half-duplex fashion.

17. The method of claim 16, further comprising transmitting modulated data by the first terminal on a second channel during an uplink subframe after the first terminal receives modulated data during the downlink subframe.

18. The method of claim 16, further comprising transmitting modulated data by the second terminal on a second channel during an uplink subframe before the second terminal receives modulated data during the downlink subframe.

19. A frequency division duplexing (FDD) wireless communication method for use by a base station, a first terminal, and a second terminal, wherein the base station transmits using a downlink subframe on a first channel and the first and second terminals transmit using an uplink subframe on a second channel, wherein the downlink subframe includes a broadcast preamble, a time division multiplex (TDM) portion, and a Time Division Multiple Access (TDMA) portion, and wherein the TDMA portion includes at least one modulation/forward error correction (PHY) mode with an associated preamble, both of which are intended for the second terminal, the method comprising:

transmitting a broadcast preamble for a base station to a first terminal and a second terminal during a downlink subframe on a first channel;

sunchronizing the first terminal and the second terminal to the base station based on the broadcast preamble;

transmitting modulated data from the second terminal to the base station during a uplink subframe on a second channel;

transmitting modulated data from the base station to the first terminal during a TDM portion of the downlink subframe on the first channel after the first terminal is synchronized with the base station;

transmitting a preamble from the base station during a TDMA portion of the downlink subframe on the first channel, wherein the preamble is transmitted after the second terminal has transmitted its modulated data to the base station;

re-synchronizing the second terminal with the base station based on the preamble transmitted by the base station on the first channel;

transmitting modulated data from the base station to the second terminal during the TDMA portion of the downlink subframe on the first channel after the second terminal is re-synchronized with the base station; and

wherein the first and second terminals operate in a full-duplex fashion.

20. The method of claim 19, further comprising transmitting the TDMA portion during the downlink subframe from the base station using a smart antenna.

21. A time division duplexing (TDD) wireless communication method for use by a base station and a first terminal and a second terminal, wherein the base station transmits using a downlink subframe and the terminals transmit using an uplink subframe, both on the same channel, wherein the downlink subframe includes a broadcast preamble and a Time Division Multiple Access (TDMA) portion, and wherein the TDMA portion includes a first modulation/forward error correction (PHY) mode with an associated preamble which is only intended for the first terminal, and a second PHY mode with an associated preamble which is only intended for the second terminal, the method comprising:

transmitting a broadcast preamble from a base station to a first terminal and a second terminal during a downlink subframe;

synchronizing the first and the second terminals to the base station based on the broadcast preamble;

transmitting a first preamble by the base station using a smart antenna to only the first terminal after transmitting the broadcast preamble, wherein the first preamble is associated with a first PHY mode;

re-synchronizing the first terminal with the base station based on the first preamble transmitted by the base station;

transmitting modulated data from the base station using the smart antenna to only the first terminal during the downlink subframe using the first PHY mode after the first terminal is synchronized with the base station; and

transmitting a second preamble from the base station using the smart antenna to only the second terminal after transmitting the modulated data to the first terminal, wherein the second preamble is associated with a second PHY mode;

re-synchronizing the second terminal with the base station based on the second preamble transmitted by the base station;

transmitting modulated data from the base station to only the second terminal during the downlink subframe using the second PHY mode after the second terminal is synchronized with the base station; and

transmitting a broadcast downlink map by the base station and during the downlink subframe which indicates when the first preamble is to be transmitted by the base station, wherein the broadcast downlink map includes at least one time indicator and a downlink interval usage code (DIUC), wherein the DIUC is indicative of the first PHY mode.

22. The method of claim 21, further comprising transmitting a broadcast uplink map by the base station and during the downlink subframe which indicates when the first terminal is to transmit modulated data to the base station during an uplink subframe.

23. The method of claim 22, wherein the downlink subframe and the uplink subframe have a combined duration of 0.5 milliseconds.

24. The method of claim 22, wherein the downlink subframe and the uplink subframe have a combined duration of 1 milliseconds.

25. The method of claim 22, wherein the downlink subframe and the uplink subframe have a combined duration of 2 milliseconds.

26. The method of claim 22, wherein the duration of the downlink subframe and the duration of the uplink subframe vary over time.

27. The method of claim 22, wherein transmitting to the first terminal and transmitting to the second terminal, both by the base station, is performed using different PHY modes.

28. The method of claim of 27, wherein transmissions during the uplink subframe and the downlink subframe are modulated using Quadrature Amplitude Modulation (QAM) symbols of adaptable modulation density.

29. The method of claim 27, wherein transmissions during the uplink subframe and the downlink subframe comprise Orthogonal Frequency Division Multiplexing (OFDM) symbols of adaptable modulation density.

30. The method of claim 27, wherein the first terminal and the second terminal use the same modulation type with different forward error correction types.

31. A frequency division duplexing (FDD) wireless communication method for use by a base station and a first terminal and a second terminal, wherein the base station transmits using a downlink subframe on a first channel and the terminals transmit using an uplink subframe on a second channel, wherein the downlink subframe includes a broadcast preamble and a Time Division Multiple Access (TDMA) portion, and wherein the TDMA portion includes a first modulation/forward error correction (PHY) mode with an associated preamble which is only intended for the first terminal, and a second PHY mode with an associated preamble which is only intended for the second terminal, the method comprising:

transmitting a broadcast preamble from a base station to a first terminal and a second terminal during a downlink subframe on a first channel;

synchronizing the first and the second terminals to the base station based on the broadcast preamble;

transmitting a first preamble by the base station using a smart antenna on the first channel to only the first terminal after transmitting the broadcast preamble, wherein the first preamble is associated with a first PHY mode;

re-synchronizing the first terminal with the base station based on the first preamble transmitted by the base station;

transmitting modulated data from the base station using the smart antenna on the first channel to only the first terminal during the downlink subframe using the first PHY mode after the first terminal is synchronized with the base station;

transmitting a second preamble by the base station using the smart antenna on the first channel to only the second terminal after transmitting the modulated data to the first terminal, wherein the second preamble is associated with a second PHY mode;

re-synchronizing the second terminal with the base station based on the second preamble transmitted by the base station;

transmitting modulated data from the base station on the first channel to only the second terminal during the downlink subframe using the second PHY mode after the second terminal is synchronized with the base station; and

transmitting a broadcast downlink map by the base station and during the downlink subframe which indicated when the first preamble is to be transmitted by the base station, wherein the broadcast downlink map includes at least one time indicator and a downlink interval usage code (DIUC), wherein the DIUC is indicative of the first PHY mode.

32. The method of claim 31, further comprising transmitting a broadcast uplink map by the base station and during the downlink subframe which indicates when the first terminal is to transmit modulated data on a second channel to the base station during an uplink subframe.

33. The method of claim 32, wherein the downlink subframe and the uplink subframe have a combined duration of 0.5 milliseconds.

34. The method of claim 33, wherein the downlink subframe and the uplink subframe have a combined duration of 1 milliseconds.

35. The method of claim 33, wherein the downlink subframe and the uplink subframe have a combined duration of 2 milliseconds.

36. The method of claim 33, wherein the duration of the downlink subframe and the duration of the uplink subframe vary over time.

37. The method of claim 33, wherein transmitting to the first terminal and transmitting to the second terminal, both by the base station, is performed using different PHY modes.

38. The method of claim of 37, wherein transmissions during the uplink subframe and the downlink subframe are modulated using Quadrature Amplitude Modulation (QAM) symbols of adaptable modulation density.

39. The method of claim 37, wherein transmissions during the uplink subframe and the downlink subframe comprise Orthogonal Frequency Division Multiplexing (OFDM) symbols of adaptable modulation density.

40. The method of claim 37, wherein the first terminal and the second terminal use the same modulation type with different forward error correction types.