Semi-Orthogonal Relay Coding for Spectrally Efficient MS-MARC Links
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Solution Overview
Problem
Current MS-MR networks face challenges in achieving maximum diversity and spectral efficiency due to imperfect decoding by relays and the need for orthogonal links, which limits transmission reliability and capacity, especially in mobile networks with Rayleigh fading.
Innovation Solution
A semi-orthogonal transmission method where relays perform iterative joint detection/decoding, interleaving, and algebraic network coding in a finite field of order greater than two, allowing simultaneous transmission on the same spectral resource, enabling maximum diversity and error reduction by exploiting non-orthogonal links.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If orthogonal links are used for source-destination and destination-repeater transmissions, then transmission reliability is improved, but spectral efficiency deteriorates due to loss of spectral efficiency from dividing radio resources among several users
Solution Approach 1:
The transmission protocol is divided into two distinct phases: first phase where sources transmit to relays and destination, second phase where relays transmit to destination. This segmentation allows non-orthogonal transmissions within each phase while maintaining overall reliability through the structured two-phase approach.
Solution Approach 2:
The system dynamically switches between orthogonal and non-orthogonal transmission modes. During the two phases, non-orthogonal links are exploited for better spectral efficiency, while the structured phase division provides the reliability benefits traditionally associated with orthogonal links.
2Device complexity
If relays perform decoding in Rayleigh fading channels without channel knowledge, then system complexity is reduced, but decoding accuracy deteriorates leading to non-zero outage probability and error propagation
Solution Approach 1:
Sources perform channel coding and transmit redundancy information before relays need to decode. This preliminary action allows relays to decode without needing channel knowledge, as the redundancy provides error correction capability that compensates for the lack of channel state information.
Solution Approach 2:
Channel coding adds redundancy beforehand to cushion against decoding errors in Rayleigh fading channels. This redundancy acts as a buffer that protects against the non-zero outage probability inherent in decoding without channel knowledge.
3Productivity
If finite field order is greater than two for network coding, then coding efficiency and diversity are improved, but computational complexity increases
Solution Approach 1:
The system changes the finite field order parameter from binary (order 2) to higher orders (greater than 2) for the network coding operations at relays. This parameter change improves coding efficiency and diversity while the structured two-phase protocol manages the associated computational complexity.
Data Source
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AI summary
The invention relates to a method (1) for semi-orthogonal transmission of a signal intended for a system with N sources (S1, S2, ... SN), M relays (R1, R2, ... RM) and a single receiver (D) whereby the simultaneous transmission on a same spectral resource by the relays is successive and not simultaneous to a simultaneous transmission on a same spectral resource by the sources, the method comprising, by relay: - a step 2 of joint iterative detection/decoding of messages (u1, u2, uN) transmitted respectively by the sources to obtain decoded messages, - a step 3 of detecting errors on the decoded messages (u1, u2, uN), - a step 4 of interleaving the detected messages without errors followed by a step 5 of algebraic network coding consisting of a linear combination in a finite group of an order strictly higher than two of the interleaved messages to obtain a coded message, the linear combinations being independent, two by two, between the relays of the system, - a step 6 of formatting comprising channel coding to generate a signal representative of the network coded message.