Physical Layer Random Access in Wideband TDD Systems
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Solution Overview
Problem
In wideband time division duplex mobile communication systems, the increased number of users leads to a higher probability of random sequence collisions and interference due to all users occupying the same channel resource, necessitating an effective random access mechanism to reduce collisions and interference.
Innovation Solution
The method involves dividing the UpPTS timeslot into unequal frequency sub-bands based on system broadcast messages, allowing terminals to select a frequency sub-band for random access based on signal-to-noise ratios or reception powers of the downlink pilot channel, and retransmitting the random access sequence if no response is received within a predetermined period.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If all users occupy the same channel resource for random access, then the system maintains simple channel structure, but the probability of random sequence collisions increases
Solution Approach 1:
The patent divides the UpPTS timeslot into multiple unequal frequency sub-bands based on system broadcast messages. Terminals select different frequency sub-bands for random access transmission, thereby segmenting the shared channel resource. This segmentation reduces the probability of random sequence collisions while maintaining relatively simple system structure.
2Ease of operation
If users transmit random access sequences in the same frequency band, then the transmission mechanism remains simple, but interference between terminals increases
Solution Approach 1:
The patent assigns different frequency sub-bands to different terminals for random access transmission. Each terminal transmits its random access sequence in a locally optimized frequency sub-band selected based on downlink pilot channel signal-to-noise ratio measurements. This local quality differentiation reduces interference between terminals while keeping the overall transmission mechanism relatively simple.
3Adaptability or versatility
If the system uses equal frequency division for random access, then resource allocation is uniform, but it cannot adapt to varying signal conditions of different terminals
Solution Approach 1:
The patent divides the UpPTS timeslot into unequal frequency sub-bands rather than equal divisions. This asymmetric division allows the system to adapt to varying signal conditions of different terminals by allocating appropriate frequency resources based on downlink pilot channel quality measurements. The asymmetric structure provides better adaptability while managing system complexity.
4Reliability
If terminals retransmit random access sequences without timeout control, then access reliability improves, but power consumption increases
Solution Approach 1:
The patent implements periodic random access sequence transmission with predetermined timeout control. Terminals retransmit random access sequences in periodic intervals only when no response is received within the timeout period. This periodic action mechanism maintains access reliability by ensuring retransmission when necessary while controlling power consumption by avoiding continuous transmission.
Data Source
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AI summary
A method for physical layer random access in wideband TDD mobile communication system is disclosed, and the method comprises: receiving the system broadcast message of the cell, obtaining the configuration information of the frequency band in frequency domain in the UpPTS time slot of the cell; and the terminal sends random access sequences to the BS in the UpPTS time slot according to the configuration information of the frequency band in the UpPTS time slot. The configuration information of the frequency band in frequency domain in the UpPTS time slot comprises the information about the frequency band number that the total bandwidth used is divided in the UpPTS time slot, the information about the bandwidth size of each frequency band, and the information about the position of the frequency point. Phod, device and terminal for physical layer random access in wideband TDD mobile communication system provided in the present invention can use the frequency bands whose time slots are different to perform network access, which can reduce the competition and collision probability when sending random access sequences, and can realize an efficient random access procedure.