Rate-less Codes for Grant-Free Multiple Access
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current wireless communication systems are sub-optimal in achieving spectral efficiency and fairness among users due to their reliance on grant-based orthogonal multiple access schemes, which are inefficient in adapting to time-varying wireless channels and prone to inaccuracies from feedback delays and channel estimation errors.
Innovation Solution
The implementation of physical layer rate-less codes enables grant-free, contention-based, and grant-based, non-orthogonal multiple access schemes, allowing for dynamic adaptation to varying channel conditions and reducing the need for explicit link adaptation and feedback overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If grant-based orthogonal multiple access schemes are used, then intra-cell interference is avoided, but spectral efficiency and adaptability to time-varying channels deteriorate
Solution Approach 1:
The patent combines rateless codes with non-orthogonal multiple access (NOMA) to merge the interference avoidance capability of orthogonal schemes with the spectral efficiency of non-orthogonal schemes. Multiple users transmit on the same time-frequency resources simultaneously, and the base station uses rateless decoding to separate and decode all user signals, achieving both high spectral efficiency and reliable interference management
Solution Approach 2:
The patent introduces dynamic adaptation through rateless codes that can adjust the coding rate based on channel conditions. The system dynamically determines when successful decoding is achieved without requiring explicit feedback about channel state, enabling automatic adaptation to time-varying channels while maintaining high spectral efficiency
2Device complexity
If grant-based orthogonal multiple access schemes are used, then resource allocation is simplified, but adaptability to time-varying wireless channels deteriorates
Solution Approach 1:
The patent implements self-service through rateless codes that automatically adapt to channel conditions without requiring external feedback or control signaling. The decoding process itself provides the adaptation mechanism - the base station continues decoding until success is achieved, automatically adjusting to channel variations without explicit link adaptation protocols
Solution Approach 2:
The patent extracts the explicit feedback and link adaptation mechanisms from the resource allocation process. By using rateless codes with successful decoding detection, the system removes the need for complex feedback loops and channel state reporting, simplifying resource allocation while maintaining adaptability through the inherent properties of rateless coding
3Reliability
If explicit link adaptation and feedback mechanisms are used, then channel conditions can be compensated, but feedback overhead and system complexity increase
Solution Approach 1:
The patent uses feedback in a minimal and efficient manner - only a single-bit indicator is fed back to signal successful decoding. This minimal feedback mechanism provides just enough information for the transmitter to know when to stop transmitting redundant packets, achieving reliable channel compensation without excessive feedback overhead
Solution Approach 2:
The patent applies partial action by using rateless codes that generate packets beyond what is minimally required for decoding. This excessive generation of coded packets ensures that enough information is available to overcome channel impairments, and the system stops exactly when decoding succeeds, avoiding waste while ensuring reliability
4Loss of time
If grant-free contention-based access is enabled, then access latency is reduced, but collisions between users increase
Solution Approach 1:
The patent converts the harmful effect of collisions into a beneficial feature. Instead of treating collisions as errors to be avoided, the rateless coding scheme treats received packets from multiple users as additional information sources. The base station accumulates packets from all users (including collisions) and uses rateless decoding to separate and decode all signals, turning collision-induced interference into useful signal diversity
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Rate-less multiple access schemes for wireless networks uses physical layer, rate-less codes to enable grant-free, contention-based, random access and grant-based, contention-free, non-orthogonal multiple access in uplink or downlink channels.