Synchronized Contention Window Full Duplex MAC Protocol
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Solution Overview
Problem
Current wireless local area networks (WLANs) face limitations in achieving full-duplex communication due to self-interference, and existing MAC protocols are not efficient in supporting legacy nodes and achieving high throughput, especially in scenarios with hidden nodes and two-hop configurations.
Innovation Solution
The Synchronized Contention Window Full Duplex (S-CW FD) protocol synchronizes backoff slots of nodes to enable simultaneous transmissions, supporting legacy IEEE 802.11 nodes and operating in both ad-hoc and infrastructure modes, with embedded FD information in packet headers to reduce overhead and manage power control for interference mitigation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If full-duplex communication is implemented in wireless networks, then throughput is doubled, but self-interference prevents successful reception
Solution Approach 1:
The patent converts the harmful self-interference into a useful signal by having the transmitting node also receive and process its own transmitted signal. The received signal contains both the desired incoming signal and the self-interference, which is treated as an additional observable component that can be utilized for synchronization and channel estimation purposes.
Solution Approach 2:
The patent introduces a synchronization mechanism using packet preambles as an intermediary element. The transmitting node sends a preamble that the receiving node uses to synchronize its backoff counter and timing, enabling coordinated full-duplex operation without direct interference between the simultaneous transmissions.
2Adaptability or versatility
If legacy IEEE 802.11 nodes are supported, then compatibility is maintained, but full-duplex operation requires substantial protocol modifications
Solution Approach 1:
The patent makes the packet preamble serve multiple functions: it acts as both a standard IEEE 802.11 synchronization signal for legacy nodes and as a full-duplex coordination mechanism for FD-capable nodes. The FD indicator field in the preamble allows legacy nodes to ignore FD-specific operations while FD nodes utilize the same structure for synchronized operation.
Solution Approach 2:
The patent performs preliminary synchronization by having the receiving node capture and process the transmitting node's packet preamble before the actual data transmission begins. This preliminary action allows the receiving node to set its backoff counter and timing in advance, ensuring synchronized full-duplex operation without requiring complex real-time coordination.
3Productivity
If nodes transmit and receive simultaneously, then channel utilization is improved, but decoding packet headers becomes difficult
Solution Approach 1:
The patent segments the communication process into distinct phases: a synchronization phase using the packet preamble where timing and backoff are coordinated, and a data transmission phase where full-duplex communication occurs. This segmentation allows the critical synchronization information to be exchanged before simultaneous transmissions begin, simplifying header decoding during the data phase.
Data Source
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AI summary
The present invention relates to a method of operating a local area network accessible by a plurality of local area network communication nodes, each station including transceiver means adapted to operate on a wireless electromagnetic wave transmission channel. The present invention more particularly relates to a synchronized contention window (S-CW) full duplex (FD) protocol enabling full duplex communication in wireless local area networks (WLAN) by means of a medium access control (MAC) protocol.