Hybrid orthogonal frequency division multiple access system and method

• US 20060256839A1
• Filed: 04/19/2006
• Published: 11/16/2006
• Est. Priority Date: 04/22/2005
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Inventors: Zhang, Guodong, Tsai, Yingming, Pan, Jung-Lin
• Granted Patent: US 7,715,460 B2
• Time in Patent Office: Days
• US Class Current: 375/131
• CPC Class Codes: H04L 27/2601 Multicarrier modulation systems
• CPC Class Codes: H04L 27/2647 Arrangements specific to the receiver only equalisation H04L27/01
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04L 5/0016 Time-frequency-code
• CPC Class Codes: H04L 5/0037 Inter-user or inter-terminal allocation
• CPC Class Codes: H04L 5/0044 allocation of payload
• CPC Class Codes: H04L 5/005 of common pilots, i.e. pilots destined for multiple users or terminals
• CPC Class Codes: H04L 5/0073 Allocation arrangements that take into account other cell interferences for intercell interference mitigation or co-ordination in orthogonal multiplex systems H04J11/005

Abstract

A hybrid orthogonal frequency division multiple access (OFDMA) system including a transmitter and a receiver is disclosed. The transmitter includes a first spread OFDMA subassembly, a first non-spread OFDMA subassembly and a first common subassembly. The first spread OFDMA subassembly spreads input data and maps the spread data to a first group of subcarriers. The first non-spread OFDMA subassembly maps input data to a second group of subcarriers. The first common subassembly transmits the input data mapped to the first and second group of subcarriers using OFDMA. The receiver includes a second spread OFDMA subassembly, a second non-spread OFDMA subassembly and a second common subassembly. The second common subassembly processes received data to recover data mapped to the subcarriers using OFDMA. The second spread OFDMA subassembly recovers the first input data by separating user data in a code domain and the second non-spread OFDMA subassembly recovers the second input data.

Claims

1. A hybrid orthogonal frequency division multiple access (OFDMA) system comprising:

a transmitter comprising;

a first spread OFDMA subassembly for spreading first input data for a first group of users and mapping spread data to a first group of subcarriers;

a first non-spread OFDMA subassembly for mapping second input data to a second group of subcarriers; and

a first common subassembly for transmitting the first input data and the second input data mapped to the first group of subcarriers and the second group of subcarriers using OFDMA; and

a receiver comprising;

a second common subassembly for processing received data to recover data mapped to the subcarriers using OFDMA;

a second spread OFDMA subassembly for recovering the first input data; and

a second non-spread OFDMA subassembly for recovering the second input data.

2. The system of claim 1 wherein the first spread OFDMA subassembly spreads the first input data in at least one of a time-domain and a frequency domain.

3. The system of claim 2 wherein the first spread OFDMA subassembly spreads the first input data by repeating the first input data at a chip rate.

4. The system of claim 1 wherein the first spread OFDMA subassembly and the first non-spread OFDMA subassembly map the subcarriers dynamically.

5. The system of claim 1 wherein the first spread OFDMA subassembly transmits common pilots on the first group of subcarriers.

6. The system of claim 1 wherein the first non-spread OFDMA subassembly implements at least one of time-domain hopping and frequency-domain hopping in mapping the second input data to the second group of subcarriers.

7. The system of claim 1 wherein the second OFDMA subassembly of the receiver comprises a Rake combiner.

8. The system of claim 1 wherein the second OFDMA subassembly of the receiver comprises a time-frequency Rake combiner.

9. The system of claim 1 wherein at least one of the transmitter and the receiver comprises multiple antennas.

10. A hybrid orthogonal frequency division multiple access (OFDMA) system comprising:

a transmitter comprising;

a spreader for spreading first input data for a first group of users to generate chips;

a first subcarrier mapping unit for mapping the chips to a first group of subcarriers;

a first serial-to-parallel (S/P) converter for converting second input data for a second group of users to first parallel data;

a second subcarrier mapping unit for mapping the first parallel data to a second group of subcarriers;

an inverse discrete Fourier transform (IDFT) processor for performing IDFT on outputs of the first subcarrier mapping unit and the second subcarrier mapping unit to generate a time domain data;

a first parallel-to-serial (P/S) converter for converting the time domain data to serial data; and

a cyclic prefix (CP) insertion unit for inserting a CP to the serial data for transmission; and

a receiver comprising;

a CP removal unit for removing a CP from received data;

a second S/P converter for converting output of the CP removal unit to second parallel data;

a discrete Fourier transform (DFT) processor for performing DFT on the second parallel data to generate frequency domain data;

an equalizer for performing equalization on the frequency domain data;

a subcarrier demapping unit for separating the frequency domain data after equalization for the first group of users and the second group of users;

a code domain user separation unit for separating the frequency domain data after equalization for the first group of users in a code domain to recover the first data; and

a second P/S converter for converting the frequency domain data after equalization for the second group of users to serial data to recover the second input data.

11. The system of claim 10 wherein the spreader spreads the first input data in at least one of a time-domain and a frequency domain.

12. The system of claim 11 wherein the spreader spreads the first input data by repeating the first input data at a chip rate.

13. The system of claim 10 wherein the first subcarrier mapping unit and the second subcarrier mapping unit map the subcarriers dynamically.

14. The system of claim 10 wherein the transmitter transmits common pilots on the first group of subcarriers.

15. The system of claim 10 wherein the second subcarrier mapping unit implements at least one of time-domain hopping and frequency-domain hopping in mapping the first parallel data to the second group of subcarriers.

16. The system of claim 10 wherein the code domain user separation unit comprises a Rake combiner.

17. The system of claim 10 wherein the code domain user separation unit comprises a time-frequency Rake combiner.

18. The system of claim 10 wherein at least one of the transmitter and the receiver comprises multiple antennas.

19. A method for transmitting data using hybrid orthogonal frequency division multiple access (OFDMA), the method comprising:

at a transmitter

spreading first input data for a first group of users to generate chips;

mapping the chips to a first group of subcarriers;

converting second input data for a second group of users to first parallel data;

mapping the first parallel data to a second group of subcarriers;

performing an inverse discrete Fourier transform (IDFT) on outputs of data mapped to the first group of subcarriers and the second group of subcarriers a time domain data;

converting the time domain data to serial data;

inserting a cyclic prefix (CP) to the serial data; and

transmitting the CP inserted data; and

at a receiver;

receiving data transmitted by the transmitter;

removing a CP from received data;

converting the CP removed data to second parallel data;

performing a discrete Fourier transform (DFT) on the second parallel data to generate frequency domain data;

performing equalization on the frequency domain data;

separating the frequency domain data after equalization for the first group of users and the second group of users;

separating the data for the first group of users in a code domain to recover the first data; and

converting the data for the second group of users to serial data to recover the second input data.

20. The method of claim 19 wherein the spreading of the first input data is performed in at least one of a time-domain and a frequency domain.

21. The method of claim 20 wherein the spreading of the first input data is performed by repeating the first input data at a chip rate.

22. The method of claim 19 wherein the first group of subcarriers and the second group of subcarriers are mapped dynamically.

23. The method of claim 19 further comprising the transmitter transmits common pilots on the first group of subcarriers.

24. The method of claim 19 wherein at least one of time-domain hopping and frequency-domain hopping is performed in mapping the first parallel data to the second group of subcarriers.

25. The method of claim 19 wherein separating the data for the first group of users in a code domain is performed by a Rake combiner.

26. The method of claim 19 wherein separating the data for the first group of users in a code domain is performed by a time-frequency Rake combiner.