Uplink Contention Resource Segmentation for LTE Collision Avoidance
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Solution Overview
Problem
In Long Term Evolution (LTE) networks, the existing scheduling-based uplink data transmission process is inefficient due to contention collisions when multiple user equipment (UEs) share the same uplink contention resource, leading to failed decoding of uplink data by the evolved base station (eNB).
Innovation Solution
The proposed solution involves configuring a shared uplink contention resource with distinct SR and data symbols, where UEs send scheduling requests (SR) and data using orthogonal code channels, enabling the eNB to differentiate and decode data from multiple UEs, even in contention scenarios, through the use of code channels, cyclic shift values, and time-domain orthogonal codes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a same uplink contention resource is configured for multiple UEs, then resource utilization is improved, but contention collision occurs leading to failed decoding
Solution Approach 1:
The uplink contention resource is segmented into distinct SR symbols and shared symbols, with further segmentation into multiple code channels (e.g., code channel 0, code channel 1). Each UE is assigned a specific code channel, allowing simultaneous transmissions to be differentiated at the eNB through code channel identification, thereby maintaining high resource utilization while preventing decoding failures.
2Reliability
If scheduling-based sending manner is used, then reliable data transmission is achieved, but time consumption increases to approximately 22.5 ms
Solution Approach 1:
The eNB pre-configures multiple code channels and their corresponding parameters (cyclic shift values, time-domain orthogonal codes) for uplink contention resources. UEs are pre-assigned to specific code channels, enabling them to immediately transmit data without waiting for scheduling grants, thus reducing latency while maintaining reliability through the structured code channel framework.
3Loss of time
If contention-based sending manner is used, then time consumption is reduced, but contention collision occurs when multiple UEs transmit simultaneously
Solution Approach 1:
Each code channel within the uplink contention resource is assigned unique local qualities through different cyclic shift values and time-domain orthogonal codes. This allows the eNB to distinguish between simultaneous transmissions from different UEs by detecting the specific code channel characteristics, thereby enabling contention-based transmission without collisions while maintaining fast access.
Data Source
AI summary
A method includes: configuring, by an eNB, a same uplink contention resource for multiple UEs; sending, by the UE, an SR to the eNB by using an SR symbol in the uplink contention resource, and sending uplink data to the eNB by using a shared symbol in the uplink contention resource; receiving, by the eNB, the SR sent by the UE by using the SR symbol in the uplink contention resource; and receiving, by the eNB, the uplink data sent by the UE by using the shared symbol in the uplink contention resource. This resolves a problem that when multiple UEs send uplink data to an eNB by using a same uplink contention resource and a contention collision occurs, the uplink contention resource is totally wasted.