Sidelink Relay Network Coding for Reliable Low-Latency Retransmission
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Solution Overview
Problem
Existing sidelink communication systems face challenges in ensuring high reliability and reducing latency, particularly in scenarios where vehicles or IoT devices experience interference, leading to unsuccessful reception of critical broadcast, multicast, or groupcast communications.
Innovation Solution
Implementing a relay node, such as a roadside unit (RSU), that monitors sidelink communications, stores received packets, and retransmits missing packets or new network-coded packets based on feedback, using network coding algorithms to enhance reliability and reduce latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional sidelink communication is used without relay nodes, then device complexity is reduced, but reliability deteriorates due to interference and unsuccessful reception
Solution Approach 1:
A relay node is introduced as an intermediary between the transmitting UE and receiving UEs. The relay node receives packets from the transmitting UE, stores them in a buffer, and retransmits them to receiving UEs that failed to decode the original transmission. This intermediary structure improves reliability by providing an additional transmission path without significantly increasing the complexity of individual communicating devices.
2Loss of time
If traditional retransmission methods are used without network coding, then device complexity is reduced, but latency increases due to multiple retransmission rounds
Solution Approach 1:
The system changes the parameter of packet encoding by applying network coding at the relay node. Instead of simply retransmitting original packets, the relay node encodes multiple packets into new coded packets that can be decoded to recover original information. This parameter change reduces latency by allowing receiving UEs to successfully decode packets with fewer retransmission rounds, while the complexity is managed through efficient encoding algorithms.
3Reliability
If network coding is implemented at relay nodes, then reliability is improved through efficient retransmission, but device complexity increases
Solution Approach 1:
The relay node performs preliminary actions by storing received packets in a buffer before retransmission. This allows the relay to have packets ready for immediate retransmission or encoding upon receiving a NACK feedback, reducing waiting time and improving reliability. The preliminary buffering action manages complexity by organizing packets systematically rather than requiring complex real-time processing during retransmission.
4Loss of information
If relay nodes with buffering are used, then loss of information is reduced through packet storage and retransmission, but device complexity increases
Solution Approach 1:
The relay node acts as an intermediary with a buffer that temporarily stores packets. This buffering capability prevents loss of information by ensuring packets are available for retransmission if initial transmissions fail. The complexity is managed by using the buffer as a simple storage mechanism rather than requiring complex error correction or retransmission protocols at the communicating UEs.
Data Source
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AI summary
Methods, systems, and devices for wireless communications are described in which sidelink communications between devices may be retransmitted using one or more nodes. A first user equipment (UE) may transmit a broadcast, multicast, or groupcast communication to a set of other UEs using sidelink resources. A node may monitor the communications and store the first UE transmission. UEs of the set of other UEs may transmit feedback reports to the node that indicate one or more missing packets of the first UE transmission. The node may retransmit one or more of the stored packets to the set of other UEs based on the feedback reports. In some cases, the sidelink communications may be encoded using a network coding algorithm, and the node may retransmit network coded packets based on the feedback reports, may transmit newly encoded packets based on the feedback reports, or combinations thereof.