Interference signal cancelling method, receiver and communicatio

Details Interference signal cancelling method, receiver and communicatio Interference signal cancelling method, receiver and communicatio

1994-09-09

1996-07-16

Chin, Stephen

Pulse or digital communications

Receivers

Particular pulse demodulator or detector

375346, 375348, 3647242, H03D 100, H04L 2706

Patent

active

055374433

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

The present invention relates to an interference signal cancelling method and a receiver using the same and, more particularly, to an interference signal cancelling method which compensates for the degradation of transmission characteristics due to co-channel or similar interference signals from other adjacent cells in digital mobile radio communication and a receiver and a communication system using such an interference signal cancelling method.
There have already been proposed several types of receivers that generate replicas from transmission symbol candidates for desired and interference signals and transmission line parameters corresponding to these two signals, subtract these replicas from a received signal to obtain an error signal, multiply the square of the error signal by -1 and use the resulting signal as a log likelihood to make a maximum likelihood decision by a maximum likelihood sequence estimator for desired and inter-channel interference signals under inter-symbol interference generating environment.
For example, W. Van Etten has proposed, as a maximum likelihood sequence estimator, a receiver using the Viterbi algorithm (W. Van Etten, "Maximum Likelihood Receiver for Multiple Channel Transmission System," IEEE Trans. on Comm., February 1976). However, this receiver is based on the assumption that the value of the impulse response of the transmission line is preknown. A receiver of the type that estimates transmission line parameters and employs a maximum likelihood sequence estimator has been proposed by Howard E. Nicols, Arithur A. Giordano and John G. Proakis. According to their proposal, the transmission line parameters are estimated and updated by an adaptation algorithm through use of an estimated value for a symbol detection which is outputted from the maximum likelihood sequence estimator after being delayed for the same period of time as a received signal sample delayed for a fixed period of time. This receiver operates well when the radio channel undergoes relatively slow time-variations. In the mobile radio channel, however, since the amplitudes and phases of desired and interference signals varyat high speed, the estimated value of the received signal sample which is delayed for a fixed period of time, as proposed by Howard E. Nicols, Arithur A. Giordano and John G. Proakis, is no longer a current estimated value, and the transmission characteristic is seriously degraded.
To improve the characteristic of an adaptive equalizer based on the maximum likelihood sequence estimation scheme, A. P. Clark, J. D. Harvey and J. P. Driscoll have proposed a Near-Maximum-Likelihood detection scheme as a solution to the poor estimation of the transmission line parameters due to the fixed delay of the received signal sample which poses a serious problem in the adaptive maximum likelihood receiver using the maximum likelihood sequence estimation scheme (A. P. Clark, J. D. Harvey and J. P. Driscoll, "Near-Maximum-Likelihood detection processes for distorted digital signals," Radio & Electronics Engineer, Vol. 48, No. 6, pp. 301-309). Moreover, A. P. Clark has proposed an FDM (Frequency Division Multiplexing) system which transmits two signals over the same frequency channel through utilization of the Near-Maximum-Likelihood detection scheme (U.S. Pat. No. 4,862,483). In this system, however, transmission signal sequence candidates (First Vector) to be stored in a memory and sets of transmission line parameters (vectors) corresponding to them are large in number and extended received signal sequence candidates (Second Vector) are sequentially chosen in decreasing order of likelihood as new transmission signal sequence candidates. Consequently, when the likelihood of the transmission signal sequence candidate (First Vector) of the highest likelihood is far higher than the likelihood of the other transmission signal sequence candidates (First Vector), the order of likelihood of the extended signal sequence candidates (Second Vector) is dependent upon the likelihood of t

REFERENCES:
patent: 5005188 (1991-04-01), Clark
patent: 5081651 (1992-01-01), Kubo
patent: 5263052 (1993-11-01), Borth et al.
patent: 5285480 (1994-02-01), Chennakeshu et al.
patent: 5291523 (1994-03-01), Bergmans et al.

Affiliated with

Also associated with

Rating

Interference signal cancelling method, receiver and communicatio does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Interference signal cancelling method, receiver and communicatio, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Interference signal cancelling method, receiver and communicatio will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-1790890