PHICH Reception in LTE-A Wireless Communication
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Solution Overview
Problem
In LTE-A systems, the use of a PHICH can lead to decreased system throughput due to interference and inefficiency, especially in subframes unsuitable for PHICH use.
Innovation Solution
A communication apparatus and method that selectively receive and transmit PHICHs based on whether the terminal monitors an E-PDCCH, avoiding PHICH use in subframes with high interference and optimizing retransmission control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PHICH is used for uplink retransmission control, then retransmission control function is provided, but system throughput decreases due to interference and inefficiency
Solution Approach 1:
The patent extracts the PHICH channel from the system by not mapping it in subframes where E-PDCCH is monitored. Instead of using PHICH for retransmission control in these subframes, the system relies on adaptive retransmission through E-PDCCH, thereby eliminating the throughput-decreasing PHICH while preserving retransmission functionality through the alternative mechanism.
2Quantity of substance
If control signals are mapped to data region (E-PDCCH), then resource shortage in control region is solved, but PHICH transmission efficiency decreases
Solution Approach 1:
The patent implements dynamic behavior by conditionally mapping PHICH based on whether the terminal monitors E-PDCCH. In subframes where E-PDCCH is monitored, PHICH is not mapped (dynamic adaptation to E-PDCCH usage). This dynamic approach allows the system to maintain PHICH transmission efficiency in appropriate subframes while enabling flexible control signal capacity management through E-PDCCH in other subframes.
3Reliability
If PHICH is transmitted in all subframes, then retransmission control is continuously provided, but interference to other cells increases
Solution Approach 1:
The patent applies local quality by differentiating PHICH mapping behavior across different subframes based on E-PDCCH monitoring requirements. In subframes where E-PDCCH is monitored (local condition), PHICH mapping is suppressed to reduce interference. In other subframes, PHICH mapping is maintained. This localized adaptation ensures retransmission control continuity through E-PDCCH in critical subframes while reducing interference in subframes where PHICH is not transmitted.
Data Source
AI summary
Provided is a wireless communication device. A PHICH reception unit determines whether a received signal in a PHICH region is an ACK signal or a NACK signal. When doing so, the PHICH reception unit does not receive a PHICH in a subframe in which a terminal monitors an E-PDCCH. A control signal reception unit outputs a retransmission prompting signal to a signal allocation unit when the signal outputted from the PHICH reception unit is a NACK signal and when a UL grant was not detected. Meanwhile, when a UL grant was detected, the control signal reception unit outputs the detected UL grant to the signal allocation unit. The signal allocation unit maps the transmission signal in accordance with the retransmission prompting signal and the UL grant and transmits the transmission signal from a wireless transmission unit.