Infrastructure Equipment Repeated Transmission Pattern
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Solution Overview
Problem
Existing mobile communications systems face challenges in extending radio coverage for low-power, simple communication devices, such as those supporting machine-type communications (MTC), especially when resource elements are already allocated for other purposes, making it difficult to implement coverage extension techniques without disrupting existing signal transmission formats.
Innovation Solution
The technique involves repeating message transmissions across subframes, specifically using the enhanced Physical Downlink Control Channel (ePDCCH) and avoiding resource elements allocated for Cell-specific Reference Signals (CRS) and Channel State Information Reference Signals (CSI-RS) to ensure reliable message reception, even in challenging radio conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If coverage extension is implemented by repeating message transmissions, then radio coverage is extended for low-power devices, but resource elements allocated for other purposes (CRS, CSI-RS) cannot be used, reducing available transmission resources
Solution Approach 1:
The transmission resources are segmented into two distinct sets: resource elements for normal transmissions (including CRS and CSI-RS) and separate resource elements for coverage-enhanced repeated transmissions. This segmentation allows the system to maintain existing resource allocations while creating dedicated resources for coverage extension, resolving the conflict between extending coverage and preserving available transmission resources.
2Reliability
If repeated transmissions are used for coverage extension, then signal detection reliability is improved, but the complexity of resource allocation and transmission formatting increases
Solution Approach 1:
The system performs preliminary actions by pre-configuring and signaling the resource element patterns for coverage-enhanced transmissions before actual data transmission begins. The network device signals the pattern of resource elements to be used for repeated transmissions, allowing the user equipment to prepare appropriate reception configurations in advance. This preliminary setup reduces the complexity during actual transmission by establishing clear, predetermined resource allocation rules.
3Reliability
If resource elements are reserved for CRS and CSI-RS, then reference signal functionality is maintained, but fewer resource elements are available for repeated message transmissions
Solution Approach 1:
The invention extracts and isolates the resource elements needed for coverage-enhanced repeated transmissions from the overall resource pool, specifically excluding resource elements allocated for CRS and CSI-RS. By taking out these reference signal resources and creating a separate resource set for repeated transmissions, the system maintains reference signal functionality intact while dedicating specific resources for coverage extension, thus resolving the conflict between maintaining reference signal functionality and maximizing transmission capacity.
Data Source
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AI summary
An infrastructure equipment for a mobile communications network comprises a transmitter and a receiver for transmitting and receiving signals via a wireless access interface to one or more communications devices. The wireless access interface comprises a down-link communications channel in which each of a plurality of time divided units comprises communications resource elements in time and frequency for allocation to transmit messages to the communications devices. The infrastructure equipment is configured to identify, for each of a plurality of time units, communications resource elements of the communications channel which cannot be allocated to transmit messages to one of the communications devices, to determine, with respect to one of the plurality of time units as a reference time unit, a number of the communications resource elements of the communications channel for repeatedly transmitting one or more message units to the communications device a plurality of times in the reference time unit, to identify, for each of the plurality of time units, a pattern of the communications resource elements for the repeated transmission of the one or more message units, within each time unit, determined with respect to the reference time unit, the pattern of the communications resource elements for each of the plurality of time units excluding the communications resource elements of the communications channel which cannot be allocated to the communications devices, and to control the transmitter to transmit the one or more message units to the communications device via the identified pattern of the communications resource elements in the plurality of time units of the wireless access interface. Accordingly the infrastructure equipment is arranged to identify a pattern of communications resource elements for performing repeated transmission of one of more message units to provide coverage extension for communications devices, which accommodates pre-allocated communications resource elements which have been specified for a different purpose in one or more of the time units so that these communications resource elements cannot be used for transmitting the one or more message units, and in which these allocated resource elements change from one time unit to another.