Channel Mode Conversion Synchronization in Wireless Portable Internet
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Solution Overview
Problem
In wireless portable Internet systems, there is a delay in converting channel modes from diversity to Band Adaptive Modulation and Coding (AMC), leading to increased transmission errors due to asynchronous CQI and REP_RSP transmissions, and difficulty in recognizing CINR of bands, which affects resource allocation and synchronization.
Innovation Solution
A method that synchronizes CQI transmission through the physical layer with REP_RSP transmission at the MAC layer by allocating uplink resources after a predetermined number of frames, allowing for timely conversion from a first channel mode to a second mode, and efficiently changing bands by controlling CQI de-allocation and bandwidth allocation sequentially.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If the terminal transmits REP_RSP after receiving REP_REQ through CQICH, then the channel quality information can be reported to the AP, but a large delay occurs before the terminal receives REP_REQ and transmits REP_RSP
Solution Approach 1:
The AP pre-allocates uplink resources for REP_RSP transmission before the actual channel mode conversion is completed. By preparing the resource allocation in advance and using a predetermined frame counter mechanism, the system eliminates the delay that would otherwise occur while waiting for REP_REQ reception and processing.
2Measurement precision
If the CINR reported to REP_RSP is increased or decreased per dB to correct the difference, then the CINR can be adjusted, but the time delay is still generated until the difference is corrected and transmission errors are increased
Solution Approach 1:
The system pre-adjusts the CINR values in the REP_RSP message before transmission, incorporating compensation for the predetermined frame counter delay. This preliminary correction ensures that the CINR values are already accurate when received by the AP, eliminating the need for post-transmission adjustment and preventing transmission errors during the correction period.
3Productivity
If the REP_RSP is transmitted to the same frame as the CQI of the changed channel mode or after the CQI has been transmitted, then the channel quality information can be sent, but it is difficult to perform transmission synchronization between the CQI and REP_RSP
Solution Approach 1:
The AP uses a predetermined frame counter to pre-determine the exact timing for REP_RSP transmission, ensuring synchronization with the CQI transmission frame. By calculating the appropriate frame offset in advance and allocating resources accordingly, the system achieves precise synchronization between the physical layer CQI transmission and the MAC layer REP_RSP transmission.
4Adaptability or versatility
If the diversity channel is converted into AMC channel mode through multiple steps, then the channel mode conversion can be completed, but the processes are complex and time-consuming
Solution Approach 1:
The system consolidates multiple channel mode conversion steps into a single streamlined process by pre-allocating uplink resources and using a predetermined frame counter mechanism. This preliminary preparation eliminates the need for multiple sequential operations, reducing the overall complexity of the conversion process while maintaining the flexibility to handle different channel modes.
Data Source
AI summary
Provided is a channel mode converting method of a wireless portable Internet system. When a diversity channel mode is converted into an Adaptive Modulation and Coding (AMC) channel mode, a radio resource for transmitting Channel Quality Information (CQI) is allocated without responding to a resource allocation request and a request between a terminal and an access point. Therefore, a delay time can be reduced on the channel mode conversion. In addition, a CQI channel for transmitting the existing channel quality information is released and a CQI channel for a new channel is allocated on the channel mode conversion. As a result, a time for changing the diversity channel CQI transmission to the AMC channel CQI transmission at the physical layer can be easily synchronized for transmitting the REP_RSP at the MAC.