E-PHICH Resource Allocation for LTE Control Channel Capacity
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Solution Overview
Problem
Current LTE systems face challenges in efficiently transmitting multiple transmission acknowledgement items due to limitations in legacy PHICH design, including spatial reuse issues, frequency domain inter-cell interference coordination, and overhead management, which are exacerbated by the introduction of new carrier types and enhanced control channels in LTE Rel-11.
Innovation Solution
The introduction of an enhanced physical HARQ indicator channel (E-PHICH) that supports increased control channel capacity, frequency-domain inter-cell interference coordination, and beamforming, allowing for improved spatial reuse and operation on new carrier types, with E-PHICH resources allocated within the PDSCH region and utilizing UE-specific reference signals for demodulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If legacy PHICH design is used, then implementation simplicity is maintained, but control channel capacity is insufficient and spatial reuse is limited
Solution Approach 1:
The PHICH is segmented into multiple groups (first PHICH group and second PHICH group) with different resource allocations and transmission characteristics. This segmentation allows the system to serve multiple UE sets simultaneously with different requirements, thereby increasing overall control channel capacity while maintaining manageable complexity through modular structure.
Solution Approach 2:
The patent introduces a new dimension of resource allocation by mapping PHICH to different resource element sets and using multiple downlink control information (DCI) formats. This dimensional expansion in the resource space enables higher control channel capacity without proportionally increasing structural complexity.
2Object-affected harmful factors
If PHICH resources are allocated in control channel region, then legacy compatibility is maintained, but frequency domain inter-cell interference coordination is insufficient
Solution Approach 1:
Different PHICH groups are allocated to different resource regions with distinct characteristics. The first PHICH group uses resources in the control channel region for legacy compatibility, while the second PHICH group uses resources in the data channel region for enhanced performance. This local differentiation allows optimized interference coordination for specific carrier types while maintaining overall system adaptability.
Solution Approach 2:
The enhanced PHICH structure serves multiple functions: it supports both legacy FDD carriers and new TDD carriers, accommodates different UE sets with varying requirements, and provides both control channel and data channel resource utilization. This multi-functionality enables the system to adapt to diverse carrier types while managing inter-cell interference effectively.
3Productivity
If multiple PHICH groups are introduced, then spatial reuse is improved, but overhead management becomes more complex
Solution Approach 1:
The patent dynamically determines which PHICH group to use based on the set of UEs requiring acknowledgment and their specific requirements. The eNodeB adapts the PHICH configuration in each subframe, selecting from multiple groups to optimize spatial reuse while minimizing overhead. This dynamic adaptation resolves the contradiction by making overhead management flexible rather than fixed.
Solution Approach 2:
Multiple PHICH groups are merged into a unified enhancement structure that shares common control elements and management mechanisms. The groups are coordinated through a single control signal structure that manages all PHICH groups collectively, thereby achieving improved spatial reuse efficiency while preventing proportional increase in overhead management complexity.
4Adaptability or versatility
If E-PHICH is introduced for enhanced capacity, then control channel capacity increases, but device complexity increases
Solution Approach 1:
The E-PHICH structure is nested within the existing LTE control channel framework. The enhanced PHICH groups are integrated with the existing DCI formats and resource allocation mechanisms, allowing the additional capacity to be achieved through nested structures rather than completely separate systems. This nesting approach increases control channel capacity while limiting the increase in overall device complexity.
Data Source
AI summary
Methods for devices, devices and computer program products for devices relate to a communication module, arranged for packet based communication, and including a receiving module. The receiving module is arranged to receive a control message, wherein the control message includes a plurality of acknowledgement information items, wherein each of the plurality of acknowledgement information items are located in a preset portion of the control message, respectively. The device further includes a determination module, arranged to determine whether the received control message is intended for the device, a selection module, arranged to select, responsive to an affirmative determination result, at least one of the plurality of acknowledgement information items based on the preset portions, and an obtaining module, arranged to obtain control data contained in the selected at least one of the plurality of acknowledgement information items.