Methods and apparatus for subframe configuration and generation in a multi-carrier communication system

• US 8,724,443 B2
• Filed: 09/06/2011
• Issued: 05/13/2014
• Est. Priority Date: 05/01/2004
• Status: Active Grant

• Current Assignee: Guangdong OPPO Mobile Telecommunications Corporation Limited
• Original Assignee: Neocific Incorporated
• Inventors: Li, Xiaodong, Lo, Titus, Li, Kemin, Huang, Haiming
• Primary Examiner(s): Rinehart, Mark
• Assistant Examiner(s): HOPKINS, MATTHEW A
• Application Number:
  US13/226,434
• Publication Number:
  US 20110317608A1
• Time in Patent Office: 980 Days
• Field of Search: 370/230.1, 709/224
• US Class Current: 370/203
• CPC Class Codes: H04B 7/2656 for structure of frame, burst
• CPC Class Codes: H04L 1/0026 Transmission of channel quality indication
• CPC Class Codes: H04L 1/1819 with retransmission of additional or different redundancy
• CPC Class Codes: H04L 27/2627 Modulators
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04L 5/0055 Physical resource allocation for ACK/NACK for physical mapping arrangements in ARQ protocols H04L1/1861
• CPC Class Codes: H04L 5/1484 operating bytewise
• CPC Class Codes: H04W 72/044 based on the type of the allocated resource
• CPC Class Codes: H04W 72/0446 Resources in time domain, e.g. slots or frames
• CPC Class Codes: H04W 72/12 Wireless traffic scheduling
• CPC Class Codes: H04W 72/30 Resource management for broadcast services

Abstract

Methods and apparatus for subframe configuration and generation in a multi-cell multi-carrier system. A frame for radio transmission in the system consists of multiple subframes, and each subframe consists of multiple Orthogonal Frequency Division Multiplexing (OFDM) symbols. Training symbols, frequency-domain data scrambling, size of Fast-Fourier Transform (FFT), or length of cyclic prefix can be configured differently for each subframe to facilitate different applications, such as unicasting or broadcasting.

Claims

1. A method of signal generation and transmission for a base station in a multi-cell orthogonal frequency division multiple access (OFDMA) wireless system having a plurality of base stations in a plurality of cells, the method comprising:

generating orthogonal frequency division multiplexing (OFDM) symbols in a plurality of subframes by;

scrambling frequency-domain data before modulation;

modulating the scrambled data to produce modulated data symbols;

generating training symbols;

mapping the modulated data symbols to frequency-domain data subcarriers and the training symbols to frequency-domain pilot subcarriers; and

converting the frequency-domain data subcarriers and frequency-domain pilot subcarriers to time-domain signals;

controlling a configuration of the training symbols used to generate the OFDM symbols differently between subframes based on characteristics of each subframe, wherein;

in a first type of subframe, the configuration of the training symbols is different among individual cells in the wireless system and based on a cell identity of each cell to facilitate unicasting; and

in a second type of subframe, the configuration of the training symbols is the same for multiple cells in the wireless system to facilitate broadcasting; and

transmitting the plurality of OFDM symbols.

2. The method of claim 1, further comprising controlling a configuration for frequency-domain data scrambling used to generate OFDM symbols differently between subframes based on characteristics of each subframe, wherein:

in the first type of subframe, the configuration for frequency-domain data scrambling is different among individual cells in the wireless system and based on a cell identity of each cell to facilitate unicasting; and

in the second type of subframe, the configuration for frequency-domain data scrambling is the same for multiple cells in the wireless system to facilitate broadcasting.

3. The method of claim 1, wherein the frequency-domain data subcarriers and frequency-domain pilot subcarriers are converted to time-domain signals using an inverse Fast Fourier Transform (FFT), and the size of the inverse FFT varies between subframes.

4. The method of claim 1, further comprising adding a cyclic prefix to a time domain signal to generate an OFDM symbol, wherein the length of the cyclic prefix varies between subframes.

5. The method of claim 1, wherein a subcarrier permutation used in the subcarrier mapping is based on a cell identity of a cell.

6. The method of claim 1, further comprising constructing a frequency-domain subchannel based on a cell identity of a cell.

7. The method of claim 1, wherein a single frequency network (SFN) is formed among the multiple cells during the data broadcasting.

8. The method of claim 1, wherein the configuration of the training symbols includes the phases, the amplitudes, or both, of the training symbols.

9. The method of claim 1, further comprising inserting a special downlink period (SDP) in a subframe for transmission of control information including a cell identity.

10. A method of signal transmission and reception for a mobile station in a multi-cell orthogonal frequency division multiple access (OFDMA) wireless system having a plurality of cells, each of the plurality of cells associated with a serving base station, the method comprising:

transmitting uplink signals to a serving base station, the uplink signals carrying control information, data packets, or both; and

receiving downlink signals comprised of a plurality of orthogonal frequency division multiplexing (OFDM) symbols in a plurality of subframes from the serving base station, wherein the received OFDM symbols were generated at the serving base station by;

scrambling frequency-domain data before modulation;

modulating the scrambled data to produce modulated data symbols;

generating training symbols;

mapping the modulated data symbols to frequency-domain data subcarriers and the training symbols to frequency-domain pilot subcarriers; and

converting the frequency-domain data subcarriers and frequency-domain pilot subcarriers to time-domain signals; and

the received training symbols in the OFDM symbols were configured differently between subframes at the serving base station based on characteristics of each subframe, wherein;

in a first type of subframe, the configuration of the training symbols is different among individual cells in the wireless system and based on a cell identity of each cell to facilitate unicasting; and

in a second type of subframe, the configuration of the training symbols is the same for multiple cells in the wireless system to facilitate broadcasting.

11. The method of claim 10, wherein the frequency-domain data scrambling used to generate OFDM symbols were configured differently between subframes at the serving base station based on characteristics of each subframe, wherein:

in the first type of subframe, the configuration for frequency-domain data scrambling is different among individual cells in the wireless system and based on a cell identity of each cell to facilitate unicasting; and

in the second type of subframe, the configuration for frequency-domain data scrambling is the same for multiple cells in the wireless system to facilitate broadcasting.

12. The method of claim 10, further comprising converting each received OFDM symbol from the time domain to the frequency domain using a Fast Fourier Transform (FFT), wherein the size of the applied FFT varies between subframes.

13. The method of claim 10, wherein the received downlink signals have an OFDM cyclic-prefix (CP) length that varies between subframes.

14. The method of claim 10, wherein the configuration of the training symbols comprises the phases, the amplitudes, or both, of the training symbols.

15. The method of claim 10, wherein a subchannel in the received downlink signals was constructed based on the cell identity of the cell.

16. The method of claim 10, wherein the uplink signals further comprise a special uplink period (SUP) in a subframe, the SUP allowing the mobile station to carry out radio functions, including initial ranging during power up and hand-off, periodic ranging, bandwidth request, or channel sounding.

17. The method of claim 10, further comprising monitoring the quality of the received OFDM symbols and sending channel quality information (COI), power control request, or both to the serving base station in the uplink signals.

18. The method of claim 10, further comprising:

receiving a transmitted packet from the serving base station;

determining whether the transmitted packet was successfully received or unsuccessfully received; and

sending an acknowledgement (ACK) to the serving base station if the packet was successfully received or a negative acknowledgement (NAK) to the serving base station if the packet was unsuccessfully received.

19. In a multi-cell orthogonal frequency division multiple access (OFDMA) wireless system having a plurality of base stations in a plurality of cells, a base station capable of generating and transmitting signals to one or more mobile stations in a cell, the base station comprising:

an apparatus configured for generating orthogonal frequency division multiplexing (OFDM) symbols in a plurality of subframes by;

scrambling frequency-domain data before modulation;

modulating the scrambled data to produce modulated data symbols;

generating training symbols;

mapping the modulated data symbols to frequency-domain data subcarriers and the training symbols to frequency-domain pilot subcarriers; and

converting the frequency-domain data subcarriers and frequency-domain pilot subcarriers to time-domain signals;

a controller for controlling a configuration of the training symbols used to generate the OFDM symbols differently between subframes based on characteristics of each subframe, wherein;

in a first type of subframe, the configuration of the training symbols is different among individual cells in the wireless system and based on a cell identity of each cell to facilitate unicasting; and

in a second type of subframe, the configuration of the training symbols is the same for multiple cells in the wireless system to facilitate broadcasting; and

a transmitter for transmitting the plurality of OFDM symbols.

20. The base station of claim 19, wherein the controller further controls a configuration for frequency-domain data scrambling used to generate OFDM symbols differently between subframes based on characteristics of each subframe, wherein:

in the first type of subframe, the configuration for frequency-domain data scrambling is different among individual cells in the wireless system and based on a cell identity of each cell to facilitate unicasting; and

in the second type of subframe, the configuration for frequency-domain data scrambling is the same for multiple cells in the wireless system to facilitate broadcasting.

21. The base station of claim 19, wherein the unicasting comprises data unicasting or voice communication.

22. The base station of claim 19, wherein the broadcasting comprises data broadcasting or video broadcasting.

23. The base station of claim 19, wherein the configuration of the training symbols comprises the phases, the amplitudes, or both, of the training symbols.

24. In a multi-cell orthogonal frequency division multiple access (OFDMA) wireless system having a plurality of cells, each of the plurality of cells associated with a serving base station, a mobile station capable of transmitting signals to and receiving signals from the serving base station, the mobile station comprising:

a transmitter configured for transmitting uplink signals to a serving base station, the uplink signals carrying control information, data packets, or both; and

a receiver configured for receiving downlink signals comprised of a plurality of orthogonal frequency division multiplexing (OFDM) symbols in a plurality of subframes from the serving base station, wherein the received OFDM symbols were generated at the serving base station by;

scrambling frequency-domain data before modulation;

modulating the scrambled data to produce modulated data symbols;

generating training symbols;

mapping the modulated data symbols to frequency-domain data subcarriers and the training symbols to frequency-domain pilot subcarriers; and

converting the frequency-domain data subcarriers and frequency-domain pilot subcarriers to time-domain signals; and

the received training symbols in the OFDM symbols were configured at the serving base station based on characteristics of each subframe, wherein;

in a first type of subframe, the configuration of the training symbols is different among individual cells in the wireless system and based on a cell identity of each cell to facilitate unicasting; and

in a second type of subframe, the configuration of the training symbols is the same for multiple cells in the wireless system to facilitate broadcasting.

25. The mobile station of claim 24, wherein the frequency-domain data scrambling used to generate OFDM symbols were configured at the serving base station based on characteristics of the each subframe, wherein:

in the first type of subframe, the configuration for frequency-domain data scrambling is different among individual cells in the wireless system and based on a cell identity of each cell to facilitate unicasting; and

in the second type of subframe, configuration for frequency-domain data scrambling is the same for multiple cells in the wireless system to facilitate broadcasting.

26. The mobile station of claim 24, wherein the unicasting comprises data unicasting or voice communication.

27. The mobile station of claim 24, wherein the broadcasting comprises data broadcasting or video broadcasting.

28. The mobile station of claim 24, wherein the configuration of the training symbols comprises the phases, the amplitudes, or both, of the training symbols.