SYSTEM AND METHOD FOR PERFORMING DIRECT MAXIMUM LIKELIHOOD DETECTION

• US 20090154605A1
• Filed: 12/12/2007
• Published: 06/18/2009
• Est. Priority Date: 12/12/2007
• Status: Abandoned Application

• Current Assignee: Motorola Mobility, Inc. (Lenovo Group Ltd.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Tan, Jun, Ghosh, Amitava, Wang, Fan
• Application Number:
  US11/954,998
• Publication Number:
  US 20090154605A1
• Time in Patent Office: Days
• US Class Current: 375/341
• CPC Class Codes: H04L 25/0204 of multiple channels
• CPC Class Codes: H04L 25/067 providing soft decisions, i.e. decisions together with an estimate of reliability H04L25/068 and H04L25/069 take precedence; sequence estimation techniques H04L25/03178
• CPC Class Codes: H04L 27/2647 Arrangements specific to the receiver only equalisation H04L27/01

Abstract

A method, wireless device, and wireless communication system perform Maximum Likelihood Detection. At least one data signal is accepting on at least one communication channel (604). The data signal is modulated with a plurality of transmitted bit values. The at least one data signal is sampled in a characteristic function domain of the data signal to produce characteristic function samples (608). A probability density function associated with the at least one data signal is determined, based upon the characteristic function samples (610). Soft decision values are determined, based upon the probability density function, for each transmitted bit value for each dimension of the at least one data signal (612).

Claims

1. A method, for performing Maximum Likelihood Detection, the method comprising:

accepting at least one data signal on at least one communication channel, wherein the data signal is modulated with a plurality of transmitted bit values;

sampling the at least one data signal in a characteristic function domain of the data signal to produce characteristic function samples;

determining, based upon the characteristic function samples, a probability density function associated with the at least one data signal; and

determining, based upon the probability density function, soft decision values for each transmitted bit value for each dimension of the at least one data signal.

2. The method of claim 1, wherein the characteristic function samples are determined as periodically sampled with a sampling period that is determined based at least on a signal-to-noise ratio associated with the wireless communication channel.

3. The method of claim 1, wherein the characteristic function samples in the characteristic function domain are determined by one of random sampling and pseudo-random sampling.

4. The method of claim 1, wherein the characteristic domain samples are determined based on at least a channel gain associated with the communication channel and an a priori estimated relative probability information associated with each channel bit value transmitted through the at least one communications channel.

5. The method of claim 1, wherein the determining characteristic domain samples determines characteristic domain samples in only one dimension.

6. The method of claim 1, further comprising:

determining a set of refined soft decision values by combining the soft decision values that have been determined over each dimension associated with the received signal for each corresponding bit in the plurality of transmitted bit values of each dimension.

7. The method of claim 1, wherein the probability density function is determined using a one-point Fourier transform.

8. The method of claim 1, wherein the determining the soft decision values further comprises:

determining a soft Log Likelihood Ratio value for each bit in the plurality of transmitted bit values using the probability density function.

9. A wireless device comprising:

a memory;

a processor communicatively coupled to the memory; and

a direct maximum likelihood detection module communicatively coupled to the memory and the processor, wherein the direct maximum likelihood detection module comprises;

a receiver adapted to accept at least one data signal on at least one communication channel, wherein the data signal is modulated with a plurality of transmitted bit values;

a characteristic domain sampler, communicatively coupled to the receiver, adapted to sample the at least one data signal in a characteristic function domain of the data signal to produce characteristic function samples;

a probability density function determiner, communicatively coupled to the characteristic domain sampler, adapted to determine, based upon the characteristic function samples, a probability density function associated with the at least one data signal; and

a soft decision value determiner, communicatively coupled to the probability density function determiner, adapted to determine, based upon the probability density function, soft decision values for each transmitted bit value for each dimension of the at least one data signal.

10. The wireless device of claim 9, wherein the characteristic domain sampler periodically samples the characteristic domain samples with a sampling period that is determined based at least on a signal-to-noise ratio associated with the wireless communication channel, and wherein the characteristic domain sampler determines characteristic domain samples based on at least a channel transfer function gain associated with the wireless communication channel and an a priori estimated relative probability information associated with each channel bit value transmitted through the at least one wireless communications channel.

11. The wireless device of claim 9, wherein the characteristic domain sampler is adapted to determine characteristic domain samples in only one dimension.

12. The wireless device of claim 9, wherein the soft decision value determiner is further adapted to determine a set of refined soft decision values combining the soft decision values that have been determined over each dimension associated with the received signal for each corresponding bit in the plurality of transmitted bit values of each dimension.

13. The wireless device of claim 9, wherein the probability density function determiner is adapted to determine the probability density function by using a one-point Fourier transform.

14. The wireless device of claim 9, wherein the soft decision value determiner is further adapted to:

determine a soft Log Likelihood Ratio value for each bit in the plurality of transmitted bit values using the probability density function.

15. A wireless communication system for performing Maximum Likelihood Detection, the wireless communication system comprising:

a plurality of base stations;

a plurality of wireless devices, wherein each wireless device in the plurality of wireless devices is communicatively coupled to at least one base station in the plurality of base stations;

wherein at least one of a base station and a wireless device comprises a

a direct maximum likelihood detection module, wherein the direct maximum likelihood detection module comprises;

a receiver adapted to accept at least one data signal on at least one communication channel, wherein the data signal is modulated with a plurality of transmitted bit values;

a characteristic domain sampler, communicatively coupled to the receiver, adapted to sample the at least one data signal in a characteristic function domain of the data signal to produce characteristic function samples;

a probability density function determiner, communicatively coupled to the characteristic domain sampler, adapted to determine, based upon the characteristic function samples, a probability density function associated with the at least one data signal; and

a soft decision value determiner, communicatively coupled to the probability density function determiner, adapted to determine, based upon the probability density function, soft decision values for each transmitted bit value for each dimension of the at least one data signal.

16. The wireless communication system of claim 15, wherein the characteristic domain sampler periodically samples the characteristic domain samples with a sampling period that is determined based at least on a signal-to-noise ratio associated with the wireless communication channel, and wherein the characteristic domain sampler determines characteristic domain samples based on at least a channel transfer function gain associated with the wireless communication channel and an a priori estimated relative probability information associated with each channel bit value transmitted through the at least one wireless communications channel.

17. The wireless communication system of claim 15, wherein the characteristic domain sampler is adapted to determine characteristic domain samples in only one dimension.

18. The wireless communication system of claim 15, wherein the soft decision value determiner is further adapted to determine a set of refined soft decision values combining the soft decision values that have been determined over each dimension associated with the received signal for each corresponding bit in the plurality of transmitted bit values of each dimension.

19. The wireless communication system of claim 15, wherein the probability density function determiner is adapted to determine the probability density function by using a one-point Fourier transform.

20. The wireless communication system of claim 15, wherein the soft decision value determiner is further adapted to:

determine a soft Log Likelihood Ratio value for each bit in the plurality of transmitted bit values using the probability density function.