Orthogonal division multiple access technique incorporating single carrier and OFDM signals

• US 20030169824A1
• Filed: 03/08/2002
• Published: 09/11/2003
• Est. Priority Date: 03/08/2002
• Status: Active Grant

• Current Assignee: Sparkmotion Incorporated (Quarterhill Inc. (f/k/a Wi-LAN Inc.))
• Original Assignee: Alvarion Limited
• Inventors: Chayat, Naftali
• Granted Patent: US 7,295,626 B2
• Time in Patent Office: Days
• US Class Current: 375/260
• CPC Class Codes: H04L 5/023 Multiplexing of multicarrier modulation signals multicarrier modulation H04L27/2601
• CPC Class Codes: H04L 5/06 the signals being represented by different frequencies combined with time-division multiplexing H04L5/26

Abstract

A multiple access technique is described, which is capable of maintaining orthogonality between transmitted signals in multipath conditions, even when part of or all of the transmitted signals belong to the family of Single Carrier modulation. The Single Carrier signals are converted into multicarrier signals which utilize just a fraction of the spectral lines by transmitting each fragment of data several times. The orthogonal multiplexing technique enables transmitters to enjoy both the advantages of OFDMA, such as noninterference between signals, adaptive bandwidth allocation and wideband diversity, and the Peak-to-Average Power Ratio advantage of the single carrier modulation. The multiplexing technique described allows to incorporate in the same multiple access system both OFDM signals and Single Carrier signals.

Claims

1. A transmitter for a multiple access passband communication system, which is capable of generating signals in which each data-carrying signal frame is composed of a integral or non-integral number of repetitions of a smaller data-carrying signal segment followed by an optional offsetting of the carrier frequency.

4. The transmitter of claim 22, where the frequency offset is achieved by placing the values into the frequency-domain array at equally spaced locations offset from the center.

9. A multiple access communication system in which the transmitters are capable of generating the transmitted signals according to the method of either claim 66 (repeated single carrier) or claim 77 (repeated OFDM), in which each transmitter is assigned a repetition factor and a frequency offset.

10. A multiple access communication system of claim 99, some transmitters are capable of generating OFDMA signals with arbitrarily chosen set of subcarriers.

13. A system of claim 10 wherein the allocation policy is governed according to transmitter capabilities, respective transmitter budget and traffic demand.

19. An allocation policy of a medium access controller which is integrated within multiple access networking system associated with down stream transmitter, multiple access receiver and data buffers, said policy determining the carrier modulation rules according to the respective transmitter modulation scheme:

in case of OFMDA transmitters determining subchannels allocation;

incase of single-carrier transmitter according to claim 13 determining repetition and offsetting factors.

11. A multiple access communication system of claims 99 or 1010, in which the transmitters are directed to use either of the modulation methods according to channel conditions.

2. A transmitter of claim 11, where the time-domain repetition effect is achieved by repetitively copying same set of signal samples.

3. A transmitter of claim 11, where the time-domain repetition effect is achieved by filling a frequency-domain array of values at equally spaced locations and performing a Fourier transform

5. The transmitter of claim 11, where a Numerically Controlled Oscillator (NCO) generates the carrier frequency offset.

6. The transmitter of claim 11, where the repeated data-carrying signal segment is a single carrier signal modulated with ASK, PSK, QAM, OQPSK, OQAM, MSK or CPFSK modulation.

7. The transmitter of claim 11, where the repeated data-carrying signal segment is an OFDM signal.

8. The transmitter of claim 11, where the segmentation-repetition-frequency offset process is performed on multiple transmit channels.

12. A system of claim 1111, in which the subcarrier set is hierarchically partitioned into smaller sets, and in which subcarrier sets are dynamically assigned to users according to resource allocation policy.

14. A single-carrier signal transmission apparatus for transmitting a signal, comprising:

modulation means for generating transmission symbol signal (carrier) from incoming source data;

means for splitting symbol stream into segments of size related to the desired repetition ratio;

replicating means for creating at least two repetitions of each segment;

filtering means for shaping signal as required by the respective modulation schemes and rejecting the extra images of the signal;

frequency offset means for shifting signal frequency center;

D/A converting means and analog filtering means for converting samples to signals.

15. A single-carrier signal transmission apparatus according to claim 14 wherein the replicating process is achieved by repetitively copying same set of signal samples

16. A single-carrier signal transmission apparatus according to claim 14 wherein the frequency offset is achieved by placing the values into the frequency-domain array at equally spaced locations offset from the center.

17. A single-carrier signal transmission apparatus according to claim 14 wherein a Numerically Controlled Oscillator (NCO) generates the carrier frequency offset.

18. A method of preparing source data for transmission using a single-carrier transmitter, said method comprising the steps of:

Generating transmission symbol signal (carrier) from incoming source data according to specified modulation scheme;

splitting symbol stream into segments of size related to the desired repetition ratio;

replicating each segment for creating at least two repetitions thereof;

shaping signal as required by the respective modulation schemes and rejecting the extra images of the signal;

Shifting signal frequency center; and

converting samples to transmission signals