Preamble Sequence Configuration for IoT Random Access Conflicts
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Solution Overview
Problem
In massive machine-type communications (MTC) scenarios, especially in IoT, random access conflicts arise due to multiple user equipment (UEs) transmitting the same preamble sequence, leading to random access failures, as existing LTE systems lack sufficient preamble sequences to handle large numbers of UEs effectively.
Innovation Solution
The proposed solution involves an access network device determining and notifying user equipment with preamble sequence information, allowing UEs to select from a configured preamble sequence space that includes time-frequency and code domain resources, thereby increasing the number of available preamble sequences, reducing conflicts and failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If user equipment randomly selects preamble sequences for random access, then the access process is simple and fast, but the probability of random access conflict increases when multiple UEs select the same preamble sequence
Solution Approach 1:
The preamble sequence space is segmented into multiple groups (first group and second group) with different properties. The first group uses normal cyclic shifts while the second group uses extended cyclic shifts, allowing UEs to be divided into different access categories based on their channel conditions and requirements, thereby reducing conflicts within each subgroup.
Solution Approach 2:
The patent extends the traditional single-dimension preamble selection by introducing multiple dimensions: normal cyclic shift domain and extended cyclic shift domain. This dimensional expansion allows UEs to select from a broader sequence space, reducing the probability of collision while maintaining the random selection mechanism.
2Quantity of substance
If the number of preamble sequences is increased to handle more UEs, then the capacity for massive connections is improved, but the system complexity and resource configuration difficulty increase
Solution Approach 1:
The patent makes the same physical uplink resources serve multiple functions by supporting both normal cyclic shifts and extended cyclic shifts on the same time-frequency resources. This allows the system to double the effective preamble sequence capacity without proportionally increasing physical resource allocation or system complexity.
Solution Approach 2:
The patent changes the cyclic shift parameter to create different preamble sequences. By using different cyclic shift values (normal and extended), the system generates multiple distinguishable sequences from the same base sequence, effectively increasing the number of available preambles without adding new physical resources.
3Device complexity
If preamble sequences with normal cyclic shift are used, then the sequence structure is simple, but the ability to differentiate UEs in challenging channel conditions is limited
Solution Approach 1:
The patent applies different cyclic shift properties to different UE scenarios. UEs in good channel conditions use normal cyclic shifts for simple access, while UEs in poor channel conditions (edge users, high mobility) use extended cyclic shifts that provide better correlation properties and differentiation capability, matching the local channel quality requirements.
Data Source
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AI summary
This application provides a preamble sequence configuration method, user equipment, and an access network device, so that the user equipment can randomly access a communications network system, reducing a probability of a random access failure. The method in embodiments of this application includes: determining, by an access network device, preamble sequence information, where the preamble sequence information includes a message used to indicate a quantity of preamble sequences; and sending, by the access network device, the preamble sequence information to user equipment, where the preamble sequence information is used by the user equipment for random access.