Distributive Medium Reservation in WLAN Beacon Frames
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing IEEE 802.11 protocol for wireless local area networks (WLANs) is not fully backwards compatible with legacy stations when implementing advanced medium reservation mechanisms, leading to potential interference from stations using the original protocol.
Innovation Solution
A distributed reservation protocol (DRP) that utilizes the Contention Free Period (CFP) information element within the beacon signal, allowing any station to reserve medium access time, ensuring compatibility with both new and legacy stations by interpreting CFP as control by an Access Point, thus avoiding collisions and hidden node issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a new medium reservation mechanism is implemented in WLAN, then collision avoidance and network efficiency are improved, but compatibility with legacy IEEE 802.11 stations deteriorates
Solution Approach 1:
The patent uses existing IEEE 802.11 beacon frame structures and CFP information elements as templates, copying their format and semantics. New reservation information is embedded within these existing beacon structures, allowing legacy stations to process them as standard beacons while new stations can interpret the embedded reservation data, thus maintaining compatibility while enabling new functionality
Solution Approach 2:
The beacon frame's CFP information element is given multiple functions: it continues to serve its original purpose of coordinating medium access in PCF mode while simultaneously carrying new distributed reservation information. This multi-functionality allows a single message structure to serve both legacy compatibility and new reservation capabilities without requiring separate protocols
2Productivity
If distributed reservation protocol is used, then medium access control is improved, but interference from legacy stations using original protocol increases
Solution Approach 1:
The patent applies preliminary anti-action by having stations broadcast reservation information in advance through beacons before actual data transmissions occur. This allows legacy stations to detect the reserved time periods in beacon frames and defer their transmissions accordingly, preventing collisions before they can occur rather than reacting to conflicts after they happen
3Reliability
If RTS-CTS mechanism is used, then collision reduction is achieved, but medium blockage time increases due to longer DATA packets
Solution Approach 1:
The patent uses beacon frames to perform preliminary reservation actions before actual data transmissions. By announcing reserved time periods in advance through beacons, the system secures medium access rights beforehand, allowing DATA packets to be transmitted without the overhead of RTS-CTS handshakes during the reserved period, thus reducing medium blockage time while maintaining collision reduction
Data Source
AI summary
Method for reservation of a medium in a radio communication network for data transmission between stations (A-E) of the network comprising at least one station (A, B, E) operating according to a first protocol (DRP) and a second station (C, D) operating according to a second protocol (802.11), the method comprises the steps of: providing a contention free period (23) within the first and second protocol; performing the reservation of the medium for the first station (A, B, E) according to the first protocol; and performing the reservation of the medium for the second station (C, D) according to the second protocol, announcing the contention free period for the first and second protocol by use of the same signal (21, 22, 31, 33). In particular a beacon signal is used, wherein the beacon includes a signal (488) which is recognized and accepted by the second stations (C, D). Further information (404) is added into the beacon frame (41) for reserving reservation periods (23) for the first stations (A, B, E).