Multiple Mode CTS and CF-End Frames for WLAN TXOP Management
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Solution Overview
Problem
Current wireless local area network (WLAN) technologies are not robust or efficient in managing multiple mode operations, particularly in recovering unused transmission opportunity (TXOP) duration and optimizing Power Save Multi-Poll (PSMP) sequences, leading to inefficient medium usage and inconsistencies in bandwidth allocation.
Innovation Solution
The implementation of multiple mode operation mechanisms, including enhanced MAC protection and PSMP sequences, which allow for efficient medium utilization by supporting multiple CTS frames, CF-End frame sequences, and flexible PSMP scheduling across different modes, enabling stations to relinquish unused TXOPs and optimize bandwidth usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dual mode protection is implemented with multiple CTS frames, then medium protection reliability is improved, but device complexity increases
Solution Approach 1:
The patent segments the protection mechanism into separate CTS frames for different modes (first CTS frame for first mode, second CTS frame for second mode). Each CTS frame independently protects its respective mode, allowing reliable medium protection without requiring a single complex unified protection mechanism.
Solution Approach 2:
The access point sends multiple CTS frames that serve multiple functions simultaneously - each CTS frame protects its designated mode while also establishing NAV values for stations in other modes. This multi-functionality improves protection reliability without proportionally increasing complexity.
2Productivity
If multiple CF-End frames are sent to release unused TXOP, then medium utilization efficiency is improved, but loss of time increases
Solution Approach 1:
The patent sends CF-End frames in advance to release unused TXOP duration before the current TXOP expires. This preliminary action allows stations to prepare for the next transmission opportunity, improving medium utilization efficiency by ensuring the medium is ready for rapid reuse without waiting for the current TXOP to naturally expire.
Solution Approach 2:
By sending multiple CF-End frames corresponding to different modes, the patent ensures continuous readiness of the medium for multiple modes simultaneously. This maintains continuity of useful action by preventing idle time between transmissions and ensuring the medium can be continuously utilized across different operational modes.
3Adaptability or versatility
If PSMP sequences are optimized for multiple modes, then adaptability is improved, but device complexity increases
Solution Approach 1:
The patent segments the PSMP sequence into mode-specific portions (first PSMP sequence portion for first mode, second PSMP sequence portion for second mode). This segmentation allows each mode to have optimized scheduling parameters while maintaining overall adaptability, reducing the complexity of managing a single unified multi-mode schedule.
Solution Approach 2:
The patent implements dynamic scheduling where the access point can selectively send different PSMP sequence portions based on the operational mode. This dynamic adaptability allows the system to optimize performance for each mode without requiring all stations to process complex unified schedules, thereby improving versatility without proportionally increasing device complexity.
Data Source
AI summary
A method and apparatus that applies medium access control (MAC) transmission opportunity (TXOP) protection for multiple mode operation in a WLAN system. In particular, MAC mechanisms are defined to support multiple mode CTS frames, and multiple mode CF-End frames sent by the AP, each in a format appropriate for the corresponding mode which may also apply to a single mode. MAC mechanisms permit truncation of TXOP duration for releasing the unused portion of the TXOP when no further data for transmission is available. Release of unused protected TXOP is possible for both protected AP transmissions and STA transmissions.