Half-Duplex Relay MIMO Throughput Loss
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Solution Overview
Problem
In MIMO communication systems, half-duplex relay stations operating in Time Division Duplex mode cause throughput loss due to the need for two time-slots for data transmission, which can lead to inefficient resource allocation and penalization of other mobile stations, especially in areas with poor signal quality or high mobile station density.
Innovation Solution
The method involves a base station selecting sets of relay stations and mobile stations to create interference-free channels using MU-MIMO techniques, where relay stations are considered as additional mobile stations during one time-slot and combined with the base station as a distributed antenna array during the next time-slot, allowing for efficient channel distribution without typical duplex-loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If half-duplex relay stations operate in Time Division Duplex mode to distribute system resources, then relay coverage and resource distribution are improved, but throughput loss occurs due to requiring two time-slots for data transmission
Solution Approach 1:
The patent merges the relay station into the distributed antenna array, combining the BS and RS antenna arrays into a unified MIMO system. This allows the RS to function as part of the transmit diversity system rather than as a separate half-duplex relay, eliminating the need for dedicated relay time-slots and avoiding throughput loss while maintaining extended coverage.
Solution Approach 2:
The relay station serves multiple functions: it acts as both a coverage extension node and an additional antenna element in the distributed antenna array. By making the RS transparent to MSs and integrating it into the MU-MIMO system, the same infrastructure supports both relay communication and MIMO spatial multiplexing without throughput penalty.
2Reliability
If relay stations are deployed to counteract non-uniform distribution of system resources, then resource fairness is improved, but system capacity decreases due to time-slot blocking
Solution Approach 1:
The patent combines the relay function with the distributed antenna function, allowing the same RS infrastructure to provide both resource distribution fairness through coverage extension and maintain system capacity by participating in MU-MIMO transmissions during the same time-slots used for direct BS-MS communication.
3Ease of manufacture
If relay stations operate in half-duplex mode to simplify deployment, then ease of deployment is improved, but effective throughput is reduced by 50% due to two-time-slot operation
Solution Approach 1:
The relay station is designed to be universally functional, operating as a standard half-duplex node for deployment simplicity while simultaneously serving as an antenna element in the distributed MIMO system. The RS remains transparent to MSs, requiring no complex processing, yet achieves full-duplex equivalent throughput through its integration into the MU-MIMO framework.
Data Source
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AI summary
The present invention relates to a method for signalling in a MIMO system. The system comprises a base station, BS 10, and at least one relay station, RS 11, operating in half duplex realized using Time Division Duplex. The BS 10 and the RS 11 distributes channels to at least one mobile station, MS 12. The method is particularly characterized in the steps where: - the BS 10 selects 301 at least one RS 11 which is served during a first time slot, T1, and selects at least one MS 12 which is served during a second time slot, T2, - the BS 10 creates 302 channels during T1 to said RS 11, - the BS 10 and said RS 11 create 303 channels during T2 to said MS 12.