SUL-Based Cell Selection for Uplink Coverage Expansion
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Solution Overview
Problem
In wireless communication systems, unequal uplink and downlink service areas lead to reduced coverage and inefficient use of service areas, particularly due to limitations in uplink transmission resources and maximum Tx power levels of user equipment (UE).
Innovation Solution
Implementing supplementary uplink (SUL) frequencies, such as 1.8 GHz, in addition to higher frequencies like 3.5 GHz, to expand the uplink service area and enable cell selection based on SUL service areas, using SUL-specific criteria and parameters for UE operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If higher frequencies (e.g., 3.5 GHz) are used for uplink transmission, then data transmission speed is improved, but uplink coverage area is reduced
Solution Approach 1:
The uplink frequency spectrum is segmented into multiple bands: higher frequencies (3.5 GHz) for fast data transmission in good coverage areas, and lower frequencies (1.8 GHz) for extended coverage in poor coverage areas. This segmentation allows the system to optimize for both speed and coverage by selecting appropriate frequency bands based on service area conditions.
Solution Approach 2:
The system dynamically changes the frequency parameter of uplink transmission based on coverage conditions. When coverage is poor, it switches to lower frequencies with better propagation characteristics; when coverage is good, it uses higher frequencies for faster data rates. This parameter adaptation resolves the contradiction between speed and coverage area.
2Length of stationary object
If maximum Tx power levels of UE are increased, then uplink transmission distance is improved, but uplink service area expansion is limited
Solution Approach 1:
Instead of relying solely on increasing Tx power, the system changes the frequency parameter to extend service area. Lower frequencies (1.8 GHz) have better propagation characteristics and can achieve larger service areas at the same power level, effectively resolving the limitation of power-based distance extension.
3Quantity of substance
If uplink transmission resources are increased, then data transmission capacity is improved, but resource efficiency is reduced
Solution Approach 1:
Different frequency resources are allocated based on local service area quality: higher frequencies (3.5 GHz) are used in areas with good coverage for high-speed data transmission, while lower frequencies (1.8 GHz) are used in areas with poor coverage for reliable connectivity. This local quality differentiation optimizes resource efficiency by matching resource characteristics to service area conditions.
Data Source
AI summary
A method, performed by a user equipment (UE), of transmitting and receiving signals in a wireless communication system, according to an embodiment, includes receiving a logical channel release request from a next-generation node B (gNB), determining a logical channel to release, an operation mode of the logical channel to release, and whether a packet data convergence protocol (PDCP) layer apparatus connected to the logical channel is re-established, based on the logical channel release request, and performing PDCP data recovery based on the determination result.