Network MIMO with Reserved Subframes for Cell Edge Reliability
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Solution Overview
Problem
Cell edge user equipment (UE) in wireless cellular networks experience low signal-to-interference plus noise ratio (SINR) due to their proximity to the edge of cells, leading to increased media access control layer (MAC) HARQ error probability, which current techniques struggle to address effectively.
Innovation Solution
The implementation of Network MIMO, where cooperating eNBs coordinate to provide diversity gain by establishing a reserved resource block space and scheduling mechanism, allowing for efficient coordination and simultaneous downlink transmission to cell edge UEs using a fast inter-eNB interface, such as the X2 interface, to enhance transmission reliability and throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cell edge UEs are served by traditional single base station transmission, then base station operation is simple, but SINR is low and HARQ error probability increases
Solution Approach 1:
The patent merges transmission resources from multiple base stations (primary eNB and secondary eNB) to serve cell edge UEs. By coordinating transmissions from both base stations using reserved resource blocks and subframes, the system achieves spatial diversity gain, improving SINR and reducing HARQ error probability while managing complexity through structured coordination protocols.
Solution Approach 2:
The patent implements preliminary actions by establishing reserved resource blocks and reserved subframes in advance for Network MIMO operations. The primary eNB and secondary eNB pre-coordinate transmission resources, including configuring reserved RB spaces and scheduling timelines, before actual data transmission to cell edge UEs, enabling efficient diversity gain without real-time complexity.
2Reliability
If reserved resource blocks are allocated for Network MIMO, then transmission reliability improves, but resource utilization efficiency decreases
Solution Approach 1:
The patent implements dynamic resource allocation where reserved resource blocks and subframes are configured semi-statically but can be adjusted based on traffic conditions. The system dynamically selects which UEs receive Network MIMO service in each reserved subframe based on channel conditions and queue status, optimizing both reliability and resource utilization by adapting to changing network states.
Solution Approach 2:
The patent changes key parameters including the number of reserved resource blocks, reserved subframe patterns, and coordination timing between primary and secondary eNBs. By optimizing these parameters based on traffic load and cell edge UE distribution, the system achieves reliable transmission while minimizing resource overhead and maximizing overall network productivity.
Data Source
AI summary
Embodiments of the invention provide a method to efficiently enable Network MIMO for use in the downlink direction. An association is established between a primary NodeB in a first cell and a secondary NodeB in an adjacent second cell. A set of downlink transmission resources is reserved for use by both the primary NodeB and the secondary NodeB. A transport block is transmitted from the secondary NodeB simultaneously with the primary NodeB to a user equipment (UE) near the edge of the first cell in response to a schedule provided by the primary NodeB. A time instance of the reserved transmission resources is released by the secondary NodeB when no simultaneous transmission of a transport block is scheduled within a minimum time.