Mobile Station Downlink Channel Synchronization in Sleep Mode
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Solution Overview
Problem
In the IEEE 802.16e communication system, when a Mobile Station (MS) is in sleep mode, it cannot recognize changes in downlink channel information, leading to mismatched Downlink Interval Usage Codes (DIUCs) between the MS and the Base Station (BS), resulting in failed data transmission and reception.
Innovation Solution
The MS detects changes in downlink channel information and reports them to the BS, ensuring both devices use the same DIUC by updating the DIUC when necessary, using specific MAC header messages to request and confirm changes, thereby enabling synchronized data transmission and reception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the MS enters sleep mode to reduce power consumption, then power consumption is reduced, but the MS cannot recognize changes in downlink channel information, causing DIUC mismatch between MS and BS
Solution Approach 1:
The MS performs ranging and detects downlink channel information before entering sleep mode, storing this information for later use. This preliminary detection allows the MS to maintain accurate DIUC values without continuous monitoring during sleep mode, thus reducing power consumption while preventing information loss.
Solution Approach 2:
The system implements a feedback mechanism where the MS reports detected downlink channel information and DIUC values to the BS upon waking from sleep mode. The BS uses this feedback to verify and update its own DIUC values, ensuring synchronization between MS and BS while allowing the MS to remain in low-power state during sleep periods.
2Reliability
If the MS periodically performs ranging to detect channel changes, then channel synchronization is maintained, but power consumption increases due to frequent wake-ups
Solution Approach 1:
The MS performs ranging and channel detection at predetermined intervals rather than continuously or upon every wake-up. This periodic action maintains adequate channel synchronization while significantly reducing the frequency of high-power operations, thus balancing reliability with power consumption.
Solution Approach 2:
The MS performs comprehensive channel detection and DIUC determination before entering sleep mode, so that upon waking it can use this pre-acquired information for a extended period without immediate re-detection. This preliminary action reduces the frequency of wake-ups required for channel maintenance.
3Measurement precision
If the MS monitors all frequency bands to detect pilot signals upon power-on, then initial synchronization is achieved, but the time required for system startup increases
Solution Approach 1:
The MS stores frequency band information and pilot signal characteristics from previous operations in memory. Upon power-on or wake-up, it retrieves this stored information to quickly identify and lock onto the serving BS without重新 scanning all frequency bands, thus maintaining detection accuracy while reducing startup time.
Solution Approach 2:
Instead of uniformly monitoring all frequency bands with equal intensity, the MS uses stored information to focus its detection efforts on specific frequency bands or regions where it previously detected strong pilot signals. This localized approach maintains detection precision while significantly reducing the overall time required.
Data Source
AI summary
An apparatus and method for transmitting and receiving a signal according to a change of downlink channel information by a mobile station in a broadband wireless access communication system. The method includes: detecting the change of the downlink channel information; receiving a report from a base station that there is data for the mobile station; and reporting the change of the downlink channel information to the base station, so that the base station and the mobile station have same downlink channel information.