Triple-Play MAC Protocol for Three-Node Bidirectional Relay
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Solution Overview
Problem
The IEEE 802.11n draft standard lacks a scheduling protocol for three-node bidirectional transmissions, which complicates communications and reduces data rate and throughput due to inadequate channel conditions between nodes.
Innovation Solution
A triple-play protocol at the MAC-layer is introduced for network-coded three-node bidirectional cooperation, utilizing a half-duplex relay node to assist in decoding and increasing system throughput through wireless network coding, with embodiments that include initial handshaking and no initial handshaking between nodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a reverse direction protocol is used for bidirectional transmissions between two nodes, then transmission scheduling is improved, but the data rate and throughput suffer due to inadequate channel conditions
Solution Approach 1:
A third relay node is introduced as an intermediary to assist bidirectional transmissions between two nodes. The relay node receives data from both nodes, performs network coding to generate combined data packets, and transmits these to both nodes. This intermediary approach improves channel utilization and increases throughput by enabling cooperative communication when direct links are inadequate.
2Productivity
If a third relay node is added to assist bidirectional transmissions, then system throughput is increased, but the communication complexity increases
Solution Approach 1:
The communication protocol is segmented into distinct phases: initial handshake phase for relay node selection and configuration, data transmission phase where the relay node receives and processes packets from both nodes, and acknowledgment phase for error handling. This segmentation manages complexity by organizing the multi-node interaction into structured, manageable stages rather than simultaneous complex operations.
3Productivity
If wireless network coding is utilized with a relay node, then transmission efficiency is improved, but the protocol complexity increases
Solution Approach 1:
The network coding function is extracted and centralized in the relay node, which performs the computationally intensive operations of receiving packets from both nodes, encoding them according to network coding algorithms, and transmitting the combined packets. This extraction concentrates the complexity in a single node rather than requiring all nodes to implement complex coding logic, thereby improving overall transmission efficiency while managing protocol complexity through functional specialization.
Data Source
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AI summary
A method and apparatus are described including transmitting a request-to-send signal, determining if a clear-to-send signal and a reverse direction transmission request signal have been received, transmitting first data, a first block acknowledgement request signal and a reverse direction grant signal responsive to the first determination, determining if a first block acknowledgement signal, second data and a second block acknowledgement request signal have been received, transmitting a second block acknowledgement signal responsive to the second determination, determining if a third block acknowledgement signal has been received and transmitting a fourth block acknowledgement signal responsive to the third determination. Further described are a method and apparatus including listening to channels, estimating channel conditions responsive to the listening, determining if a signal has been received, determining if channel conditions are adequate to act as a relay node multicasting a relay node clear to send signal responsive to the first and second determinations and multicasting a block acknowledgement signal and data responsive to the first and second determinations.