Wireless Communication Terminal Random Access Contention Window
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Solution Overview
Problem
In multi-user communication systems, existing methods for resource unit allocation in OFDMA (Orthogonal Frequency Division Multiple Access) face inefficiencies, such as reduced resource usage due to terminals transitioning to sleep mode or having no uplink transmission requests, and lack of fairness in contention window selection, leading to frame collisions and unsuccessful transmissions.
Innovation Solution
A wireless communication method where a base station transmits a trigger frame specifying resource units for random access, allowing terminals to select and use resource units randomly, with a mechanism to adjust the contention window value based on transmission success or failure to ensure fairness and optimize resource utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a trigger frame specifies terminals for UL-OFDMA transmission, then transmission timing can be synchronized, but resource units are not efficiently used when terminals are in sleep mode or have no uplink transmission requests
Solution Approach 1:
The trigger frame is designed to serve multiple functions: it can specify particular terminals for scheduled UL-OFDMA transmission, or it can indicate resource units without terminal specification for random access. This multi-functionality allows the system to adapt between scheduled and random access modes based on terminal availability and transmission requests, resolving the contradiction between timing synchronization and resource efficiency.
2Productivity
If terminals select resource units randomly from STA-unspecified RUs, then resource utilization improves, but frame collisions occur when multiple terminals select the same resource unit
Solution Approach 1:
The contention window (CW) for random access is made dynamic rather than fixed. The CW size is adjusted based on transmission outcomes: when frame collisions occur or transmissions fail, the CW is increased to reduce collision probability; when transmissions succeed, the CW can be decreased to improve resource utilization. This dynamic adjustment resolves the contradiction between resource utilization and transmission reliability.
3Device complexity
If the contention window is selected under the same condition as successful terminals, then protocol simplicity is maintained, but fairness is compromised for terminals that experience transmission failures
Solution Approach 1:
The terminal uses feedback from transmission outcomes (success or failure) to adjust its contention window selection. When a transmission fails or collision occurs, the terminal receives no acknowledgment and uses this feedback to increase its CW for the next random access attempt. This feedback mechanism ensures fairness by giving terminals that experience failures better chances in subsequent attempts, while maintaining protocol simplicity through straightforward conditional logic.
Data Source
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AI summary
According to one embodiment, a wireless communication terminal includes: at least one antenna; a receiver; a transmitter; a communication processor; a network processor; and a memory. The transmitter is configured to transmit a first frame including information to specify a plurality of frequency components. The communication processor is configured to determine whether or not a second frame is received via each of the plurality of frequency components. The transmitter is configured to transmit a third frame including first information concerning a first value range which is used to determine whether to respond to the first frame, the first value range being dependent on a number of frequency components via which the second frame has been received. The first frame or the third frame includes the first data cached in the memory or information based on the first data.