PHICH Resource Allocation in LTE-A Carrier Aggregation
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Solution Overview
Problem
In LTE-A systems with Carrier Aggregation, PHICH resource collisions occur due to asymmetrical uplink and downlink CC transmissions, leading to misjudgment and degraded transmission quality, as existing algorithms fail to ensure unique PHICH resource locations for each UE.
Innovation Solution
The solution involves changing the encoding mode for the lowest PRB index of PUSCHs, where the minimum value amongst the lowest PRB index numbers of uplink CCs is set to the sum of PRBs across all CCs, ensuring each UE has a distinct PRB index, thereby preventing PHICH resource collisions and ensuring compatibility with LTE systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the existing PHICH resource calculation algorithm is used in LTE-A with Carrier Aggregation, then the system supports multiple CCs and flexible spectrum allocation, but PHICH resource collisions occur between different UEs leading to misjudgment and degraded transmission quality
Solution Approach 1:
The patent modifies the parameter IPRB-RAlowest-index used in PHICH resource calculation. Specifically, it changes the encoding mode of the lowest PRB index by setting the minimum value amongst the lowest PRB index numbers of uplink CCs to the sum of PRBs across all CCs. This parameter change ensures that each UE calculates a unique PHICH resource location even in asymmetric uplink-downlink CC configurations, thereby preventing PHICH resource collisions while maintaining Carrier Aggregation functionality
Solution Approach 2:
The patent applies different PRB index encoding rules to different UEs based on their specific CC configurations. By making the minimum PRB index value UE-specific (calculated as the sum of PRBs of all uplink CCs for that UE), each UE receives locally optimized PHICH resource allocation that prevents collision with other UEs, while the overall system maintains flexibility through Carrier Aggregation
2Productivity
If multiple uplink CCs are configured for a UE, then spectrum utilization is improved, but asymmetrical uplink and downlink CC transmissions cause PHICH resource collisions
Solution Approach 1:
The patent changes the calculation parameter IPRB-RAlowest-index from a fixed or simple allocated value to a UE-specific value derived from the sum of all uplink CC PRBs. This parameter transformation ensures that even when multiple uplink CCs are configured for high spectrum utilization, each UE's PHICH resource location remains unique and collision-free, effectively eliminating the harmful effect of PHICH resource collision in asymmetric configurations
3Reliability
If the lowest PRB index is re-encoded to prevent PHICH collision, then PHICH resource uniqueness is ensured, but compatibility with existing LTE systems must be maintained
Solution Approach 1:
The patent introduces a modified parameter calculation method that is backward compatible. The new encoding mode sets the minimum PRB index to the sum of all uplink CC PRBs, which ensures unique PHICH resources. This parameter change is designed to work within the existing LTE framework, allowing UEs to calculate PHICH resources using the same fundamental algorithm while incorporating the new encoding rule, thus maintaining compatibility with existing LTE systems while preventing PHICH resource collisions
Data Source
AI summary
The present invention relates to a method, device and system for solving channel collision, which are applied to a Long Term Evaluation Advanced (LTE-A) system. The method includes: receiving control information transmitted by a base station; transmitting uplink data to the base station according to the control information; and receiving decoding results on the uplink data from the base station, and determining the resource location of a Physical Hybrid ARQ Indicator Channel (PHICH) according to the control information, thereby determining the decoding result corresponding to a User Equipment (UE) itself. The implementation of the embodiments of the present invention can avoid the problem of collision the channel resources of the PHICH determined by the UE when the LTE-A has to be compatible with the LTE.