Random Access Message Configuration for Faster Handover Synchronization
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Solution Overview
Problem
Conventional random access channel (RACH) procedures in wireless communications experience collisions and require extended time for connectivity due to limited information provided by random access preamble sequences, leading to inefficiencies in establishing connections with base stations.
Innovation Solution
Configuring user equipment (UE) with different transmission parameters for contention-free random access (CFRA) and contention-based random access (CBRA) procedures, utilizing dedicated time/frequency domain resources to enhance connectivity by providing additional information and reducing interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If conventional RACH procedures use random access preamble sequences with limited information, then device complexity is reduced, but connection establishment time increases and collisions occur more frequently
Solution Approach 1:
The RACH procedure is segmented into multiple independent components: preamble sequence selection, payload message transmission, and uplink grant reception. Each component operates independently to reduce overall procedure time and collision impact. The preamble sequence is segmented into multiple sequences with different information contents, allowing parallel transmission attempts without full procedure collision.
Solution Approach 2:
The UE performs preliminary actions by selecting and preparing multiple preamble sequences and associated payload messages before initiating the RACH procedure. This preliminary preparation includes configuring transmission parameters and selecting from pre-defined preamble sets, enabling faster response when a preamble is successfully received and reducing the overall connection establishment time.
2Reliability
If conventional RACH procedures transmit only one preamble sequence, then transmission power requirements are reduced, but connection establishment reliability decreases due to collisions
Solution Approach 1:
The system implements partial action by transmitting a subset of prepared preamble sequences and payload messages rather than all possible combinations. The UE selects and transmits multiple preambles with associated payloads in a controlled manner, providing excessive information content in each transmission attempt to increase the probability of successful connection establishment while managing power consumption through selective transmission rather than exhaustive transmission of all possibilities.
3Speed
If RACH procedures use limited preamble information content, then message transmission complexity is reduced, but synchronization speed decreases
Solution Approach 1:
The system changes parameters by varying the information content and structure of payload messages associated with different preamble sequences. Different preamble sequences are associated with different payload configurations, allowing the system to adapt message transmission complexity based on the specific connection establishment scenario. This parameter variation enables faster synchronization for simple cases while maintaining the capability for more complex information exchange when needed.
Data Source
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AI summary
Methods, systems, and devices for wireless communication are described. In some wireless systems, a base station may configure a user equipment (UE) for random access (RACH) message transmission in dedicated RACH resources during, for example, a handover process. The contention-free random access (CFRA) resources may allow the UE to transmit RACH messages at a higher transmission power than contention-based random access (CBRA) resources. The base station may indicate, to the UE, RACH transmission parameters for CFRA that are different than parameters for CBRA. These parameters may include configuration information, frequency division multiplexing information, RACH retransmission parameters, target received power, response window length, etc. The UE may use the indicated RACH transmission parameters to transmit a RACH message to the base station. The base station may respond with a RACH response message, and the base station and UE may synchronize upon completion of the RACH procedure.