PRACH Resource Allocation for Cellular Access
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Solution Overview
Problem
The existing random-access (RA) procedure in cellular communication networks, particularly in LTE and New Radio (NR) systems, faces challenges in defining a sufficient number of unique PRACH preamble sequences, leading to potential collisions between user equipment (UE) transmissions, and current solutions either reduce resource usage efficiency or incur unacceptable latency.
Innovation Solution
The method involves allocating PRACH resources as combinations of time, frequency, and sequence resources, allowing wireless devices to select from a larger set of unique preambles, thereby increasing the addressable space without incurring excessive resource overhead or latency, by configuring multiple time and frequency resources within the Master Information Block (MIB) and Physical Broadcast Channel (PBCH).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the number of PRACH preamble sequences is increased to reduce collisions, then the addressable space increases, but the resource overhead and latency increase
Solution Approach 1:
The patent extends the PRACH resource space by introducing multiple time resources (different time instances) and frequency resources (different frequency locations) in addition to the sequence dimension. This multi-dimensional resource allocation allows the system to provide a larger number of unique preambles without requiring proportionally longer processing times, as UEs can select from diverse time-frequency-sequence combinations rather than only sequence variations.
Solution Approach 2:
The patent segments the PRACH resources into multiple independent dimensions: time resources (different time instances), frequency resources (different frequency locations), and sequence resources (different preamble sequences). This segmentation allows the system to distribute the preamble selection across multiple resources, increasing the total addressable space while maintaining efficient access procedures through structured resource organization.
2Quantity of substance
If multiple time and frequency resources are allocated for PRACH preambles, then the number of unique preambles increases, but the resource overhead increases
Solution Approach 1:
The patent utilizes multiple dimensions (time, frequency, and sequence) to expand the PRACH resource space. By distributing preambles across these dimensions rather than relying solely on sequence variations, the system achieves a larger number of unique preambles with more efficient resource utilization, reducing the overhead associated with any single dimension.
Solution Approach 2:
The patent creates a multi-functional PRACH resource structure where time resources, frequency resources, and sequence resources all serve the common purpose of providing unique preamble identification. This universal approach allows any combination of time-frequency-sequence to function as a distinct preamble resource, maximizing the utility of each resource element and reducing overall overhead.
Data Source
AI summary
A method in a wireless device for performing an access procedure comprises: receiving an indication from a network node, the indication comprising an allocation of a plurality of Physical Random Access Channel (PRACH) resources for PRACH preamble transmission, wherein the plurality of PRACH resources comprises one of a first combination and a second combination of time resources, frequency resources and sequences, wherein the first combination comprises a plurality of time resources, one or more frequency resources and a first plurality of sequences and the second combination comprises one or more time resources, a plurality of frequency resources and a second plurality of sequences; and selecting a PRACH resource among the plurality of PRACH resources. A wireless device for performing this method is also disclosed.