RACH Preamble Segmentation for Extended Cell Coverage
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Solution Overview
Problem
The existing preamble structure in broadband wireless communication systems limits the maximum cell radius due to a trade-off between cell radius and preamble length, resulting in reduced preamble detection capability and energy, which restricts the extension of cell coverage.
Innovation Solution
A method and apparatus for transmitting and receiving preambles using Single Carrier-Frequency Division Multiple Access (SC-FDMA) that extends the preamble length beyond a basic unit, divides it into segments, and uses transmit diversity with multiple antennas, along with a guard time to maintain detection performance across larger cell radii.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the preamble length is increased to extend cell coverage, then the cell radius is improved, but the preamble detection capability and energy are reduced
Solution Approach 1:
The patent divides the extended preamble into multiple segments, each transmitted in a separate time slot. This segmentation allows the base station to receive and process multiple preamble segments sequentially, maintaining detection capability while achieving extended cell coverage through the cumulative information from all segments.
Solution Approach 2:
The patent employs periodic transmission of preamble segments at regular time intervals. This periodic action ensures that the base station can systematically process each segment and maintain synchronization, thereby preserving detection reliability while extending the effective cell radius through time-dispersed transmission.
2Area of stationary object
If the preamble length is increased to extend cell coverage, then the cell radius is improved, but the access time delay is increased
Solution Approach 1:
By segmenting the preamble transmission across multiple time slots, the patent enables the mobile terminal to transmit preamble information more efficiently. The base station can process segments in parallel or sequentially without requiring the terminal to wait for a single long preamble transmission, thereby reducing overall access time delay while maintaining extended cell coverage capability.
Solution Approach 2:
The patent introduces dynamic adjustment mechanisms where the base station can determine the optimal processing timing for preamble segments based on actual channel conditions and terminal requirements. This dynamic approach allows flexible allocation of time resources, reducing access delays while preserving the extended cell coverage benefit.
3Reliability
If the preamble is divided into segments transmitted using different antennas, then transmit diversity is improved, but the device complexity is increased
Solution Approach 1:
The patent segments the preamble transmission across multiple antennas, where each antenna transmits a specific segment. This segmentation approach provides transmit diversity by distributing the transmission load across multiple spatial channels, improving detection reliability through independent fading paths while keeping the terminal structure relatively simple through automated segment assignment.
Solution Approach 2:
The patent implements a universal preamble transmission framework where the mobile terminal can dynamically select from multiple antennas based on channel conditions. This multi-functional approach allows the same terminal hardware to serve multiple transmission purposes without requiring dedicated complex structures for each antenna configuration, thereby improving detection while managing device complexity.
Data Source
AI summary
A method for transmitting a preamble over a Random Access CHannel (RACH) in a wireless communication system is provided. The method includes generating a preamble having a length longer than a basic transmission unit, and dividing the preamble into preambles having a length less than the basic transmission unit; and sequentially transmitting the divided preambles over the RACH using different antennas.