MAC Control Element for Fast SRS and CQI Termination
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Solution Overview
Problem
Current LTE systems lack efficient mechanisms to quickly terminate uplink signaling, particularly for secondary cells and primary cells, due to limitations in TA timer management and MAC layer control elements, leading to slow and granular control over SRS and CQI reporting.
Innovation Solution
Introduction of a new Medium Access Control (MAC) Control Element (CE) that allows mobile terminals to selectively activate and deactivate SRS and CQI reports for serving cells, using bitmaps to indicate transmission status for each cell, enabling faster control of uplink signaling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If TA timer expiration is used to terminate uplink signaling, then signaling termination occurs, but the termination is slow and not immediate
Solution Approach 1:
The patent applies preliminary action by sending a MAC CE command to the UE before the TA timer expires, instructing the UE to stop SRS and CQI transmissions in advance. This allows the network to control the termination timing precisely when needed, rather than waiting for the TA timer to naturally expire, thereby achieving immediate signaling termination without the delay inherent in timer-based approaches.
2Measurement precision
If MAC CE control is implemented for SRS and CQI termination, then control precision improves, but device complexity increases
Solution Approach 1:
The patent applies universality by designing the MAC CE to serve multiple functions: it controls both SRS and CQI transmissions, can target individual cells or multiple cells simultaneously, and can be used for both activation and termination of uplink signaling. This multi-functional design achieves precise control over uplink signaling while avoiding the need for separate control mechanisms for each signaling type, thereby limiting the increase in device complexity.
Solution Approach 2:
The patent applies segmentation by dividing the control into cell-specific bitmap fields within the MAC CE, allowing independent control of SRS and CQI for each served cell. This segmented approach enables precise granular control where needed while maintaining simplicity for cases where broader control is sufficient, balancing control precision with implementation complexity.
3Reliability
If periodic SRS and CQI transmissions are maintained for all serving cells, then channel information availability is improved, but uplink resource usage increases
Solution Approach 1:
The patent applies dynamics by enabling the network to dynamically activate or deactivate SRS and CQI transmissions for each serving cell based on current channel conditions, traffic requirements, and interference levels. This dynamic control allows the system to maintain reliable channel information for active cells while eliminating unnecessary transmissions in inactive cells, thereby reducing uplink energy consumption while preserving channel information availability where needed.
Data Source
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AI summary
Methods and operations in mobile terminals (100) and base stations (20) are disclosed which control uplink signaling. Amethod in a mobile terminal (100) controlsuplink signaling to a base station(20), and includes receiving (310) a MAC CEfrom the base station(20). The MAC CE indicates whether at least one of SRS or CQIreports should be transmitted for one or more serving cells configured for the mobile terminal(100). Transmission of at least one of the SRS or the CQI reports for the one or more serving cells from the mobile terminal (100) to the base station (20) is selectively activated and deactivated (320) responsive to the MAC CE. Related methods by base stations(20) and operations by base stations(20)and mobile terminals (100) are disclosed.