Bandwidth-Part Random Access Mapping for Downlink Resource Savings
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Solution Overview
Problem
In 5G communications systems, the existing method for random access processes on bandwidth parts leads to a significant waste of downlink resources due to the network device sending random access responses and physical downlink control channels on all configured downlink bandwidth parts, as it cannot determine which user equipment is sending the random access preamble until after receiving Msg3.
Innovation Solution
Establishing a correspondence between downlink and uplink bandwidth parts or between downlink/uplink bandwidth parts and random access configurations, allowing the network device to send random access responses and scheduling messages only on the relevant bandwidth parts, thereby optimizing resource usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the network device sends random access responses and PDCCH on all configured downlink bandwidth parts, then the user equipment can reliably receive the messages, but downlink resources are severely wasted
Solution Approach 1:
The patent segments the downlink bandwidth parts into multiple parts and establishes a correspondence relationship between them. The network device determines a specific downlink bandwidth part based on the uplink bandwidth part used by the UE for random access, rather than transmitting on all downlink bandwidth parts. This segmentation approach maintains reliable message delivery while significantly reducing downlink resource consumption by limiting transmissions to only the relevant bandwidth part.
2Reliability
If the network device transmits on all configured downlink bandwidth parts, then message delivery is ensured, but resource efficiency deteriorates
Solution Approach 1:
The patent applies local quality by making the downlink bandwidth part selection specific to the uplink bandwidth part used by the UE. Instead of uniform transmission across all downlink bandwidth parts, the network device selectively transmits random access responses and PDCCH on the locally determined relevant downlink bandwidth part that corresponds to the UE's uplink activity, thereby improving resource efficiency while maintaining delivery reliability.
3Reliability
If random access responses are sent on all downlink bandwidth parts, then reception reliability is improved, but resource consumption increases
Solution Approach 1:
The patent implements preliminary action by establishing the correspondence relationship between uplink and downlink bandwidth parts before the random access procedure. The network device pre-configures multiple downlink bandwidth parts and their correspondence with uplink bandwidth parts, enabling it to quickly determine the appropriate downlink bandwidth part for response transmission based on the UE's uplink selection, thus avoiding unnecessary transmissions and reducing resource consumption.
Data Source
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AI summary
This application provides a random access method, user equipment, and a network device. The method on a user equipment side includes: selecting, by user equipment, a random access preamble from a random access preamble set, and selecting a random access channel resource from a random access channel resource set; sending, by the user equipment, the random access preamble by using the random access channel resource; and receiving, by the user equipment, a random access response message on a first downlink bandwidth part; where at least one of the random access preamble set or the random access channel resource set corresponds to the first downlink bandwidth part, and the random access channel resource includes at least one of a random access channel time domain resource or a random access channel frequency domain resource. In this method, a network device sends a random access response on only a downlink bandwidth part corresponding to random access configuration based on the foregoing correspondence, thereby avoiding a waste of downlink resources.