Voting system for improving the performance of single-user decoders within an iterative multi-user detection system
View Patent ↗A system is presented that provides real-time performance for iterative multi-user detectors, such as Turbo MUDs, which are used to separate simultaneous transmissions on the same frequency, by permitting the MUD to use a less computationally intense, fast-processing algorithm and to correct for errors caused by the fast processing. In order to reduce the errors, a voting system is coupled to the output of the multi-user detector within the iterative system. The voting system provides confidence values on a bit-by-bit basis for the estimates made by the multi-user detector, with the confidence values then being utilized as soft inputs to a bank of conventional single-user decoders.
1. In a system to separate incoming interfering signals, apparatus for improving the performance of a multi-user detector coupled to the incoming signal in which said multi-user detector provides as an output an ordered number of best guesses as to what a particular incoming bit is, comprising:
a voting unit connected to said multi-user detector for averaging for one user the best guesses for said incoming bit, thus to provide a soft output for improving the performance of the multi-user detector.
2. A method for reducing the computational complexity of a multi-user detection system in which an incoming data stream having a number of bits from different users is applied to a multi-user detector, comprising the steps of:
providing the multi-user detector with a fast algorithm which examines less than the total number of possibilities for each of the bits of data in the incoming data stream, the algorithm resulting in prioritized best guesses as to what an incoming bit is; and,
for a given bit, averaging a predetermined number of best guesses for a predetermined user to provide a number corresponding to the average of the best guesses, whereby real-time performance can be achieved through the use of said fast algorithm.
3. In a multi-user detection system, a method for increasing the number of users accommodated by a multi-user detector in which a number of best guesses of what a particular bit is for a given user is established as the output of the multi-user detector, comprising the step of:
averaging the best guesses for a given user for a given bit so as to form a soft input to the single-user detector, whereby less computationally complex algorithms may be used in the multi-user detector to increase the number of users that can be accommodated in a given time interval.
4. The method of claim 3 , wherein the multi-user detector utilizes algorithms which for each bit of incoming data analyzes less than the total number of possibilities so as to decrease processing time, such that the increased number of users is accommodated in real time.