RACH Preamble Collision Resolution via Spatial Beamforming
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Solution Overview
Problem
In wireless communication networks, especially in 5G and beyond 5G networks, existing random access procedures face challenges such as preamble collisions during initial access, leading to increased access delay, energy inefficiency, and higher failure rates due to power ramping and inaccurate channel state information, particularly in dense networks with massive machine-type communications and IoT devices.
Innovation Solution
The method involves early detection and resolution of preamble collisions through beamformed collision resolution signals, allowing devices to select different RACH preambles and occasions based on signal quality measurements, and enabling beam refinement during RRC setup, thereby avoiding power ramping and enhancing access efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If beamformed collision resolution signals are transmitted to resolve preamble collisions, then access delay is reduced and connection establishment is faster, but device complexity and network node complexity increase due to beamforming operations and collision detection mechanisms
Solution Approach 1:
The network node performs collision detection and resolution signal transmission during the random access response phase (step 2), before the device would otherwise need to perform power ramping and retransmit preambles. This preliminary action resolves collisions early in the access procedure, reducing access delay while concentrating the complexity in the network node that has the processing capabilities.
Solution Approach 2:
The patent introduces collision resolution signals as an intermediary mechanism between the network node and devices. These signals carry collision resolution information that mediates the conflict between multiple devices using the same preamble, enabling fast resolution without requiring complex interactions between devices themselves.
2Use of energy by moving object
If power ramping is avoided through early collision resolution, then energy consumption is reduced, but measurement precision of channel state information may be affected
Solution Approach 1:
The network node uses feedback from the random access response to determine whether collisions occurred and to select appropriate collision resolution signals. This feedback mechanism enables the network to adapt its response based on the actual reception conditions, ensuring accurate channel state information is obtained even when power ramping is avoided.
Solution Approach 2:
The patent changes the parameter of transmission power strategy by avoiding power ramping altogether through early collision resolution. Instead of increasing power on retransmissions, the system uses beamformed collision resolution signals to successfully establish connection on the first attempt, reducing energy consumption while maintaining connection reliability.
3Reliability
If beam refinement is performed during RRC setup, then connection establishment is optimized and access failure rate is reduced, but the complexity of the setup procedure increases
Solution Approach 1:
Beam refinement is performed as a preliminary action during the RRC setup phase, before actual data transmission begins. This early beam refinement ensures optimal beam conditions are established beforehand, reducing access failures during subsequent communications while the complexity is confined to the setup procedure rather than ongoing operations.
Data Source
AI summary
A network node in a communication network can perform random access channel (“RACH”) preamble collision resolution (“CR”) based on spatial information. The network node can receive respective random access (“RA”) requests from two or more communication devices. The network node can determine whether to transmit an indication of the CR based on whether the RA requests collided. Subsequent to determining whether to transmit the indication of the CR, the network node can transmit one or more RA responses toward the two or more communication devices.