PUCCH Resource Allocation for Multi-Cell HARQ Feedback Latency
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Solution Overview
Problem
Current mobile communication systems face challenges in efficiently managing ACK/NACK and CQI transmissions between multiple NodeBs, particularly in LTE Rel-10, where HARQ-ACK transmissions on two antenna ports for PUCCH format 1a/1b are not effectively coordinated, leading to delays and increased latency in multi-site scheduling systems.
Innovation Solution
The solution involves determining the PUCCH resource index based on downlink assignment, allowing for HARQ-ACK transmission on two antenna ports, and configuring PUCCH resources to accommodate X2 delays between eNBs, enabling separate PUCCH transmissions for each cell and coordinated scheduling to minimize mutual interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If HARQ-ACK transmissions are sent on two antenna ports for PUCCH format 1a/1b in multi-site scheduling, then system capacity and coordination between eNBs are improved, but transmission latency and delays increase due to X2 interface delays between sites
Solution Approach 1:
The patent segments the feedback transmission by allowing separate PUCCH transmissions for each cell on different antenna ports. This enables independent handling of HARQ-ACK feedback for each site, reducing the need for coordination delays over the X2 interface while maintaining multi-site scheduling capability.
Solution Approach 2:
The patent introduces a spatial dimension by utilizing two antenna ports for PUCCH transmissions. This dimensional expansion allows simultaneous or near-simultaneous feedback transmission to multiple eNBs, bypassing the sequential X2 interface delay constraint and improving overall system throughput.
2Reliability
If separate PUCCH transmissions are configured for each cell in multi-site scheduling, then interference coordination between sites is improved, but resource allocation complexity and device complexity increase
Solution Approach 1:
The patent employs a universal PUCCH resource configuration that can be applied across multiple cells and antenna ports. By defining a common set of resource allocation rules and parameters that work for both single-cell and multi-cell scenarios, the patent reduces the complexity burden while maintaining the ability to coordinate interference effectively.
3Reliability
If additional HARQ processes are configured to accommodate X2 delays, then feedback transmission reliability is improved, but processing overhead and system resource consumption increase
Solution Approach 1:
The patent implements preliminary action by pre-configuring multiple HARQ process IDs and PUCCH resources before multi-site scheduling operations begin. This advance preparation allows the system to handle X2 delays without requiring dynamic resource allocation or additional processing overhead during actual feedback transmission, as all necessary resources are already in place.
Data Source
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AI summary
Systems, methods, and instrumentalities are disclosed for a user equipment (UE) to provide feedback in a multi-site scheduling system (e.g., a system where multiple entities may schedule and/or send data to the UE). For example, the UE may receive a first data from a first network entity and a second data from a second network entity. A network entity may include entities that transmit data and/or control information to the UE, e.g., an eNodeB (eNB). The UE may generate feedback relating to received data, such as ACK/NACK information or channel state information (CSI). The UE may send a first feedback relating to the first data in a first subframe and a second feedback relating to the second data in a second subframe.