Two-Step Random Access Under DRX for Lower Signaling Latency
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Solution Overview
Problem
Existing wireless communication systems face inefficiencies in random access procedures, particularly in scenarios with discontinuous reception, leading to increased latency and resource utilization inefficiencies.
Innovation Solution
A two-step random access procedure is introduced, optimizing the random access process by reducing the number of steps required for wireless devices to establish communication with a base station, thereby improving latency and resource utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional four-step random access procedure is used, then reliability of connection establishment is improved, but latency and number of signaling steps increase
Solution Approach 1:
The patent segments the random access procedure into two distinct steps: (1) preamble transmission and opportunity message transmission in Msg A, and (2) random access response and contention resolution in Msg B. This segmentation consolidates multiple traditional steps into fewer exchanges, reducing latency while maintaining connection establishment reliability through structured message handling and acknowledgment mechanisms.
Solution Approach 2:
The patent implements preliminary action by having the wireless device transmit both the preamble and the opportunity message (containing uplink data or control information) simultaneously in Msg A. This preliminary consolidation of actions eliminates the need for separate transmission steps, reducing the overall random access latency while ensuring that connection establishment proceeds reliably with all necessary information provided upfront.
2Use of energy by moving object
If discontinuous reception is implemented, then energy consumption is reduced, but random access procedure efficiency deteriorates
Solution Approach 1:
The patent extracts the uplink data and control information transmission from the traditional multi-step random access procedure and places it directly in Msg A alongside the preamble. This extraction allows the wireless device to complete the random access procedure in fewer steps, improving efficiency while maintaining discontinuous reception benefits by reducing the time the device needs to remain actively listening for responses.
Solution Approach 2:
The patent merges the preamble transmission with the opportunity message transmission in a single Msg A transmission. This combining of functions reduces the number of separate transmission and reception events, thereby improving random access procedure efficiency while allowing the wireless device to return to sleep mode more quickly, preserving energy consumption benefits of discontinuous reception.
3Loss of time
If the number of random access steps is reduced, then latency is decreased, but signaling complexity per step increases
Solution Approach 1:
The patent applies universality by designing Msg A to serve multiple functions simultaneously: it contains the preamble for random access initiation, uplink data for transmission, and control information for scheduling requests. This multi-functionality consolidates what would traditionally require multiple separate messages into a single composite message, reducing latency while managing signaling complexity through standardized field structures that can be processed efficiently by both transmitter and receiver.
Data Source
AI summary
A wireless device receives one or more configuration parameters indicating one or more radio network temporary identifiers (RNTIs) to monitor, via downlink control channels, during an active time of DRX operation. The wireless device selects, for transmission of a message-A of a random access procedure, one or more resources, where the message-A comprises a preamble and a payload and the payload comprises a C-RNTI. The wireless device starts a response window based on transmitting the preamble via at least one resource of the one or more resources. Based on dropping transmission of the payload and during the response window, the wireless device monitors the downlink control channels for a first RNTI, where the first RNTI is associated with a response to the preamble and determined based on the at least one resource, and does not monitor the downlink control channels for the one or more RNTIs.