LTE eNB Cell Edge Interference Mitigation via Resource Element Allocation
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Solution Overview
Problem
In LTE wireless networks, devices at the cell edge experience low signal strength and significant interference, leading to inefficient resource allocation and reduced coverage due to the assignment of minimum bandwidth, resulting in wasted resources and degraded voice call quality.
Innovation Solution
An enhanced Node B system that determines the location of User Equipment at the cell edge and allocates resources by Resource Elements (REs) instead of entire Resource Blocks (RBs, allowing for more efficient use of bandwidth and mitigating interference, thereby optimizing communication resources and improving coverage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If minimum bandwidth of 180 KHz (one Resource Block) is assigned to each UE for voice calls, then coverage is improved, but resource efficiency deteriorates and interference increases at cell edge
Solution Approach 1:
The patent segments the Resource Block into smaller Resource Elements (REs). Instead of allocating the entire 180 KHz RB to each UE, the system divides it into 12 subcarriers × 7 symbols = 84 REs per slot, allowing granular allocation. This enables assigning only the necessary portion of bandwidth to each voice call (typically 2-3 REs per slot), improving resource efficiency while maintaining coverage through selective RE allocation at cell edge.
2Reliability
If minimum bandwidth of 180 KHz is assigned to each UE, then coverage is improved, but interference increases at cell edge region
Solution Approach 1:
The patent implements local quality by applying different allocation strategies based on UE location. For cell center UEs, traditional RB allocation is used. For cell edge UEs experiencing interference, the system selectively allocates specific REs with better channel conditions and applies interference coordination techniques on those specific REs, rather than uniformly allocating entire RBs. This localized approach reduces interference impact while maintaining coverage.
3Ease of operation
If entire Resource Blocks are allocated to UEs, then simplicity of resource management is maintained, but resource utilization efficiency deteriorates
Solution Approach 1:
The patent introduces dynamic allocation at the RE level for cell edge UEs. The eNB determines channel conditions and interference levels for each RE, then dynamically selects which REs to allocate to each UE based on real-time conditions. This dynamic approach allows the system to adapt to varying channel conditions and maximize resource utilization, with the complexity managed through standardized procedures and algorithms.
4Reliability
If 180 KHz bandwidth is assigned to voice calls, then coverage degradation is compensated, but spectral efficiency deteriorates
Solution Approach 1:
The patent changes the allocation parameter from coarse-grained RB units (180 KHz) to fine-grained RE units (15 KHz per subcarrier). This parameter change enables the system to allocate precisely the amount of bandwidth needed for each voice call (e.g., 2-3 REs = 30-45 KHz) rather than forcing allocation of the entire 180 KHz RB. The coverage requirement is met through selective RE allocation with appropriate power control and modulation schemes, while spectral efficiency improves through reduced bandwidth waste.
Data Source
AI summary
An enhanced Node B (eNB) and method for interference mitigation at a cell edge region in a Long Term Evolution (LTE) wireless network are provided. The eNB in one example embodiment includes a transceiver system for communicating with a User Equipment (UE) registered with the eNB and a processing system coupled to the transceiver system and configured to receive a signal strength and an interference information from the UE via the transceiver system, with the processing system configured to determine if the UE is located at a cell edge region of the eNB, determine if the UE is experiencing interference, and allocate by Resource Elements (REs) in the communications being transferred from the eNB to the UE if the UE is located at the cell edge region and if the UE is experiencing an unacceptable level of interference.