Determining Data Channel Start Subframe via Control Indicator
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Solution Overview
Problem
In wireless communication systems, particularly for M2M applications, there is a need to determine the starting subframe of data channels accurately due to variations in path-loss and coverage issues, which can lead to misunderstandings between base stations and mobile devices regarding the start time of physical channel transmissions.
Innovation Solution
User Equipment (UE) monitors control channel candidates that occupy multiple subframes, decodes the control channel, and determines the starting subframe of the data channel using a known gap or subframe indicator, potentially applying predefined rules to accurately identify the start time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If physical channels are repeated to improve coverage for M2M devices, then coverage is improved, but misunderstanding between base station and mobile station on start time of transmission occurs
Solution Approach 1:
A subframe indicator is introduced as an intermediary element within the control channel to convey start subframe information. This indicator acts as a mediator between the base station and mobile station, providing explicit timing information that resolves the synchronization misunderstanding caused by physical channel repetitions.
Solution Approach 2:
The start subframe information is conveyed in advance through the control channel before the actual data channel transmission begins. By providing the subframe indicator preliminarily, the mobile station can prepare and synchronize its reception timing before the repeated physical channels are transmitted, preventing timing misunderstandings.
2Reliability
If control channel occupies multiple subframes, then coverage is extended, but determination of data channel starting subframe becomes complex
Solution Approach 1:
The start subframe information is extracted and conveyed through a dedicated subframe indicator field within the control channel message. This separates the timing information from the control channel structure itself, providing a clear and standardized method for determining the data channel start subframe regardless of how many subframes the control channel occupies.
Solution Approach 2:
The subframe indicator provides explicit parameter information about the start subframe, changing the approach from implicit timing derivation to explicit parameter communication. This allows the mobile station to directly obtain the start subframe value without complex calculations, simplifying the determination process even when the control channel spans multiple subframes.
Data Source
AI summary
Apparatus and method are provided to determine the starting subframe of a data channel. In one novel aspect, the UE monitors one or more control channel candidates, which at least one of the control channel candidate occupies a plurality of the subframes. The UE detects a control channel intended for the UE, decodes the control channel and determines the starting subframe of the data channel based on the control channel and a known gap. In another novel aspect, the UE further obtains a subframe indicator from the control channel. The subframe indicator signals either the number of subframes between the starting subframe of the data channel and the starting subframe of the control channel, or the number of subframes of the control channel, or the starting subframe of the data channel. In another embodiment, predefined rule can be applied to the subframe indicator to determining the starting subframe of the data channel.