MTC Device HARQ ACK/NACK Reception via EPDCCH
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Solution Overview
Problem
Machine type communication (MTC) devices in LTE networks face challenges in receiving hybrid automatic repeat request (HARQ) acknowledgment (ACK)/non-acknowledgment (NACK) signals due to operating on a reduced band, which affects their ability to receive physical hybrid-ARQ indicator channels (PHICH) transmitted over the entire system band.
Innovation Solution
The method involves an MTC device determining a radio network temporary identifier (RNTI) and monitoring the downlink control channel within a search space to receive HARQ ACK/NACK signals by decoding the downlink control channel scrambled with the determined RNTI, allowing it to correctly receive ACK/NACK signals for uplink data transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If MTC device operates on a reduced band (sub-band), then device cost is reduced, but the device cannot correctly receive PHICH transmitted over the entire system band
Solution Approach 1:
The patent introduces a new downlink control channel (EPDCCH) as an intermediary to carry HARQ ACK/NACK signals for MTC devices. Instead of relying on the traditional PHICH which is transmitted over the entire system band, the EPDCCH is specifically designed to be transmitted within the MTC device's sub-band, acting as a mediator that bridges the gap between the base station and MTC devices operating on reduced bands.
Solution Approach 2:
The patent applies local quality by transmitting the EPDCCH specifically within the MTC device's sub-band rather than using the entire system band. This localized transmission approach ensures that MTC devices can receive control signals within their operational frequency range while maintaining cost-effectiveness by using reduced bands.
2Reliability
If MTC device uses existing PDCCH and PHICH, then HARQ ACK/NACK can be received, but the device cannot operate on a reduced band
Solution Approach 1:
The patent segments the control channel functionality by introducing a separate EPDCCH specifically for MTC devices, distinct from the traditional PDCCH and PHICH. This segmentation allows MTC devices to operate independently on reduced bands without being constrained by the system-wide control channel structure.
Solution Approach 2:
The patent adds a new dimension to the control channel architecture by introducing EPDCCH with enhanced functionality for MTC devices. This new dimension includes support for reduced band operation, multiple RNTI types, and flexible resource allocation, enabling MTC devices to operate adaptively on sub-bands while maintaining reliable HARQ feedback.
3Reliability
If MTC device determines RNTI among multiple new RNTIs and monitors downlink control channel, then it can receive ACK/NACK signals, but device complexity increases
Solution Approach 1:
The patent implements self-service by enabling MTC devices to autonomously determine their own RNTI from a set of new RNTIs and independently monitor the EPDCCH for their specific control signals. This self-service capability reduces the need for complex base station coordination and simplifies the overall system architecture.
Solution Approach 2:
The patent introduces new RNTI parameters specifically designed for MTC devices, including MTC-RNTI, MCCH-RNTI, and P-RNTI. These parameter changes enable differentiated handling of MTC devices and facilitate efficient resource allocation and signal reception without requiring complex device-side processing.
Data Source
AI summary
The present disclosure provides a method for a machine type communication (MTC) device to receive a hybrid automatic repeat request (HARQ) acknowledgement (ACK)/non-acknowledgement (NACK) signal. The method can include the steps of: the MTC device transmitting a physical uplink control channel (PUCCH) including uplink data; the MTC device determining a radio network temporary identifier (RNTI) for itself from among a plurality of new RNTIs; monitoring the reception of a downlink control channel in a search space; and receiving a HARQ ACK/NACK signal for the transmission of the uplink data by decoding a downlink control channel scrambled with the determined RNTI.