Multi-radio WLAN MAC Manager for Contention Delay Reduction
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Solution Overview
Problem
In multi-radio wireless systems, independent radios contend for the same medium at the MAC and PHY layers, leading to data transmission delays due to contention mechanisms like RTS/CTS, which hinder efficient WLAN connectivity in mobile devices.
Innovation Solution
The implementation of a MAC manager logic that coordinates the operation of multiple MAC devices with distinct MAC addresses, allowing for reduced or eliminated delays by determining the optimal radio transceiver for data transmission based on factors such as packet error rate, modulation and coding scheme, and power consumption, and controlling data transmission within a network allocation vector (NAV) duration without engaging a DCF backoff algorithm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple independent WLAN radios are added to improve throughput, then data transmission capacity is improved, but transmission delay increases due to contention at MAC and PHY layers
Solution Approach 1:
The patent combines multiple WLAN radios (first and second radio systems) into a coordinated system where a single MAC layer manages transmissions for both radios. This merging eliminates inter-radio contention at the MAC layer while maintaining parallel transmission capabilities at the physical layer, thus improving throughput without incurring contention delays.
Solution Approach 2:
The patent introduces a single MAC layer as an intermediary that sits between the network interface and multiple radio systems. This intermediary coordinates transmissions, manages NAV (Network Allocation Vector) for both radios, and eliminates the need for independent MAC layer contention, thereby reducing transmission delay while maintaining multi-radio throughput capability.
2Reliability
If RTS/CTS mechanism is used to prevent hidden node problem, then transmission reliability is improved, but transmission delay increases due to additional handshaking steps
Solution Approach 1:
The patent makes the single MAC layer universal by having it manage transmissions for both the first and second radio systems. This unified MAC layer implements RTS/CTS coordination for both radios simultaneously, eliminating the need for separate handshaking sequences and reducing overall delay while maintaining reliability through coordinated medium access.
3Reliability
If DCF backoff algorithm is implemented for medium access control, then collision avoidance is improved, but transmission speed decreases due to random waiting periods
Solution Approach 1:
The patent extracts the DCF backoff algorithm from the individual radio systems and implements it at the unified MAC layer level. This extraction allows the backoff mechanism to operate once for the entire multi-radio system rather than independently for each radio, thereby maintaining collision avoidance while eliminating redundant waiting periods and improving transmission speed.
Data Source
AI summary
An apparatus includes a first media access control (MAC) device comprising a first radio transceiver and having a first MAC address and a second MAC device comprising a second radio transceiver and having a second MAC address. The second MAC device is operatively coupled to the first MAC device. The first MAC device is operative to receive first MAC layer data for the first MAC device and receive second MAC layer data for the second MAC device, and transmit the first MAC layer data and the second MAC layer data to an access point (AP) using the first radio transceiver of the first MAC device.