Response Frame Type Indication in Wireless Networks
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Solution Overview
Problem
The current IEEE 802.11 TGah standard for wireless local area networks (WLANs) lacks a clear distinction between different types of ACK and Block ACK (BA) frames, making it difficult for stations to determine when to initiate channel access, leading to potential packet collisions due to ambiguity in response frame type indications.
Innovation Solution
A method is introduced to classify response frame types based on their transmission durations, using predefined indication values in the signal (SIG) field of the physical layer header, allowing stations to defer channel access for specific time periods corresponding to the frame types, thereby improving channel access coordination without increasing signaling overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If a two-bit response frame type indication is used in the SIG field, then the signaling overhead is kept low, but the distinction between different ACK and BA frame types becomes ambiguous
Solution Approach 1:
The response frame type indication is segmented into multiple categories: ACK frames (immediate acknowledgment), BA frames (block acknowledgment), and no ACK frames. Each category is assigned a specific two-bit indication value (00, 01, 10 respectively), enabling clear distinction between different frame types while maintaining compact signaling.
Solution Approach 2:
The patent uses a two-bit indication field which provides 4 possible values (00, 01, 10, 11). While only 3 categories are needed (ACK, BA, no ACK), the extra value (11) is reserved for future use or special cases. This approach provides sufficient distinction for current needs while maintaining efficiency, avoiding the complexity of larger indication fields.
2Reliability
If stations wait for uncertain duration to access the channel, then packet collisions may occur, but if they defer access for fixed time periods, then channel access efficiency decreases
Solution Approach 1:
Stations perform preliminary action by deferring channel access for predetermined time periods based on the response frame type indication received in the SIG field. If an ACK frame is indicated (00), stations wait for a first time period; if a BA frame is indicated (01), they wait for a second time period; if no ACK is indicated (10), they wait for a third time period. This preliminary deferral prevents packet collisions while maintaining channel access efficiency.
Data Source
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AI summary
Embodiments are provided for indicating response frame types according to response frame durations in a wireless network. The embodiments include defining a plurality of response frame types in accordance to different transmission durations. The different response frame types are assigned corresponding indication values. When transmitting a current frame to a receiver entity, a transmitter entity selects a response frame type from the defined response frame types, and indicates in the current frame the selected response frame type using the assigned indication value. When a third entity receives the current frame, the third entity waits for a time period about equal to a predefined inter-frame and backoff time before transmitting a new frame. Upon determining that the indication value in the current frame is for sending a response frame, the third entity also waits an additional time period about equal to the transmission duration of the indicated response frame type.