Relay Node PRACH Region Allocation for Random Access Identification
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Solution Overview
Problem
In LTE wireless communication systems, identifying the relay node used by user equipment (UE) for random access is challenging due to the use of the same system information across all intra-cell relay nodes and UEs, which complicates the base station's ability to determine the reception timing of the physical channel related to the random access, especially considering propagation latency.
Innovation Solution
A physical channel communication method where relay nodes receive system information containing PRACH region allocation information, allowing them to transmit random access preambles to the base station on relay node-specific resource regions, enabling the base station to identify the UE attached to each relay node by using time or frequency indices for PRACH region allocation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the base station uses common system information for all relay nodes and UEs, then the system complexity is reduced and resource allocation is simplified, but the base station cannot identify which relay node a UE is attached to, making it impossible to determine the reception timing of random access preambles considering propagation latency
Solution Approach 1:
The patent segments the common system information into two parts: common parameters (preamble sequences, RA-RNTI, transmission power) that are shared by all relay nodes and UEs, and relay node-specific parameters (PRACH region allocation information) that are individually assigned to each relay node. This segmentation allows the base station to maintain simplified common system information while incorporating necessary identification information through the relay node-specific PRACH region allocation, thereby resolving the contradiction between system complexity reduction and relay node identification capability.
2Ease of manufacture
If relay nodes transmit random access preambles using common resource regions, then resource allocation is simplified, but multiple relay nodes' preambles overlap in time and frequency, causing interference and making it impossible for the base station to identify the source relay node
Solution Approach 1:
The patent applies local quality by allocating different PRACH region parameters (time indices, frequency indices, or both) to each relay node individually. This means that while all relay nodes use the same preamble sequences and RA-RNTI (maintaining commonality), each relay node transmits on its locally designated time-frequency resources. This local differentiation eliminates interference between relay nodes and enables the base station to identify the source relay node, while maintaining overall system simplicity through the common framework.
3Measurement precision
If the base station allocates relay node-specific PRACH region information, then it can identify the source relay node and determine reception timing, but the system information becomes more complex and requires additional signaling overhead
Solution Approach 1:
The patent resolves the complexity issue by introducing additional dimensions for resource allocation - specifically, allocating PRACH regions in the time dimension (different subframes), frequency dimension (different frequency resources), or both. Rather than complicating the existing system information structure, the patent extends the resource allocation into new dimensional spaces, allowing precise relay node identification through time-frequency indexing without fundamentally altering the core system information framework.
Data Source
AI summary
A physical channel communication method and apparatus for random access in a cellular communication system including a plurality of relay nodes and user equipments using the same system information is provided. The physical channel communication method for random access in a wireless communication system according to the present invention includes receiving, by at least two relay nodes connected to a base station, system information containing a Physical Random Access CHannel (PRACH) region allocation information for identifying user equipments attached to the relay nodes; receiving PRACHs for random accesses transmitted by the user equipments; and transmitting the PRACHs to the base station on relay node-specific resource regions according to the PRACH region allocation information.