Relay Node Signal Delay Compensation for MTC Coverage
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Solution Overview
Problem
Third and fourth generation mobile telecommunication systems face challenges in deploying machine type communication (MTC) devices due to their complex and expensive radio transceivers, which are not suitable for low-power, battery-operated devices with reduced transmission power, often deployed in remote locations with poor radio propagation conditions.
Innovation Solution
A communications device that uses a relay node to extend coverage by transmitting signals via a second wireless access interface, such as WiFi, to an LTE network, allowing for synchronization of data transmission and acknowledgment processes, and determining additional delays caused by the relay node to adjust transmission timing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If complex radio transceivers are used in MTC devices to support advanced data modulation techniques, then communication reliability is improved, but device complexity and cost increase
Solution Approach 1:
A relay node is introduced as an intermediary between the MTC device and the base station. The relay node receives signals from the MTC device using simpler radio transceiver capabilities and retransmits them to the base station, allowing the MTC device to communicate reliably without requiring complex transceivers. The relay node handles the complex modulation and signal processing functions.
2Use of energy by moving object
If low power transmission is used in battery-operated MTC devices, then energy consumption is reduced, but transmission power capability deteriorates
Solution Approach 1:
The relay node acts as a mediator that receives low-power signals from the battery-operated MTC device and retransmits them to the base station with appropriate power levels. This allows the MTC device to operate at low power consumption while still achieving reliable communication with the network infrastructure.
3Area of stationary object
If relay node transmission is used to extend coverage, then coverage area is improved, but transmission delay increases
Solution Approach 1:
The relay node determines and communicates the additional delay caused by its transmission to the base station in advance. The base station uses this advance information to adjust its expectations for signal arrival times, allowing the synchronous HARQ process to continue functioning correctly despite the relay node introducing additional delay.
4Reliability
If synchronization is maintained in HARQ processes with relay nodes, then communication reliability is improved, but timing complexity increases
Solution Approach 1:
The relay node provides feedback information about the additional delay it introduces to the base station. This feedback mechanism allows the base station to adjust its timing expectations and maintain synchronization in the HARQ process. The relay node transmits an indication of the additional delay, enabling the base station to compensate for the timing difference.
Data Source
AI summary
A controller configured in combination with a transmitter and a receiver to transmit signals via a second wireless access interface to a communications apparatus operating as a relay node, the signals for transmission to infrastructure equipment by the communications apparatus as if the signals were transmitted by the communications device via a first wireless communications interface, to receive signals from the infrastructure via the first wireless access interface, to determine an additional delay caused by transmission of the signals to the communications apparatus acting as the relay node via the second wireless access interface compared with a time taken which would have been taken to transmit the signals to the infrastructure equipment as if transmitted via the first wireless access interface, and to transmit to the infrastructure equipment an indication from which the infrastructure equipment can derive the determined additional delay for adjusting transmission or reception of the synchronized response.