Wireless LAN Control Response Frame Rate Determination
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Solution Overview
Problem
In wireless LAN environments, the coexistence of high throughput (HT) stations and legacy stations with different transmission capabilities leads to medium access fairness issues due to the inability of legacy stations to interpret HT frames, resulting in unequal access and potential collisions, as they rely solely on physical carrier sensing and experience frame check sequence errors.
Innovation Solution
A method to determine the transmission rate of a control response frame by obtaining and matching transmission parameters from the data transmission frame, allowing HT and legacy stations to access the medium equally, which involves searching for corresponding parameters and selecting the appropriate transmission rate, either from the receiving station's supported rates or the maximum basic rate, to ensure fair medium access.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If HT stations transmit data at high transmission rates, then throughput is improved, but legacy stations cannot interpret the frames causing FCS errors and medium access unfairness
Solution Approach 1:
The patent introduces a rate indication field as an intermediary element in the frame structure. This field acts as a mediator that conveys transmission rate information to legacy stations, enabling them to understand and properly handle frames from HT stations without requiring full interpretation capability of the data payload, thus resolving the FCS error issue while maintaining high throughput
Solution Approach 2:
The patent segments the frame into distinct functional parts: a header portion that legacy stations can interpret (including the new rate indication field) and a data portion that may use advanced modulation schemes. This segmentation allows legacy stations to process the frame header successfully and use the rate indication for medium access decisions, while HT stations can utilize the full high-rate data transmission capability
2Reliability
If legacy stations rely only on physical carrier sensing, then they can detect signals, but they cannot perform virtual carrier sensing leading to collision risks and reduced medium access fairness
Solution Approach 1:
The rate indication field serves as an intermediary information element that enables legacy stations to perform virtual carrier sensing. By extracting the transmission rate from this field and comparing it with their own capabilities, legacy stations can determine whether to defer access, effectively implementing virtual carrier sensing without requiring full frame interpretation capability
Solution Approach 2:
The patent enables legacy stations to perform preliminary assessment of frame compatibility by examining the rate indication field in the header before attempting full frame processing. This preliminary action allows them to make informed medium access decisions early in the reception process, improving overall medium access efficiency and reducing collision risks
3Productivity
If the control response frame is transmitted at the same high rate as data frames, then throughput is maximized, but legacy stations cannot decode the acknowledgment leading to protocol failures
Solution Approach 1:
The patent applies local quality by using different transmission rates for different parts of the communication process. Control response frames use a legacy-compatible rate ensuring all stations can decode acknowledgments, while data frames use high-rate modulation for maximum throughput. This localized differentiation of transmission quality resolves the compatibility issue while maintaining overall system productivity
Data Source
AI summary
A method is provided for determining a transmission rate of a control response frame for acknowledging data receipt in a wireless local area network. The method includes obtaining transmission parameters of a transmitting station from a data transmission frame received from the transmitting station, searching a receiving station for transmission parameters which correspond to the transmission parameters of the transmitting station, determining the transmission rate of the control response frame according to transmission parameters of the receiving station if the transmission parameters corresponding to the transmission parameters of the transmitting station are found in the receiving station, and determining a maximum rate among a set of basic transmission rates to be the transmission rate of the control response frame if the transmission parameters corresponding to the transmission parameters of the transmitting station are not found in the receiving station.