Segmented Access Sequence Allocation for Cellular RACH Optimization
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Solution Overview
Problem
In large cellular communication systems, the random access channel (RACH) overhead is high due to the use of identical sequences by all user equipment, leading to increased collision probability and access latency, especially in large cells where path loss and frequency offset vary significantly across users.
Innovation Solution
A segmented access scheme is implemented, where user equipment selects a sequence set based on its intra-cell location and transmission information, allowing for different sequence lengths and modulation schemes, and inserts intentional delay information to reduce sequence dependency and collision probability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If identical sequences are used by all user equipment for random access, then sequence allocation is simple, but collision probability increases and RACH overhead becomes high
Solution Approach 1:
The patent segments the single sequence set into multiple sequence sets (first sequence set and second sequence set) based on user equipment location within the cell. Users in different locations are assigned different sequence sets, dividing the sequence space to reduce collision probability while maintaining manageable allocation complexity
Solution Approach 2:
Different sequence sets are assigned to different spatial locations within the cell. The first sequence set is used by users in a first location and the second sequence set is used by users in a second location, creating location-dependent sequence allocation that adapts to spatial variations in traffic patterns
2Device complexity
If identical sequences are used by all user equipment, then device complexity is low, but RACH overhead increases in large cells
Solution Approach 1:
The patent segments users into different groups based on their location within the cell and assigns different sequence sets to each group. This segmentation allows the system to reduce RACH overhead by enabling more efficient sequence utilization across large cells while keeping the complexity manageable through location-based classification
3Reliability
If sequence sets are differentiated by user location, then collision probability decreases, but base station search load increases
Solution Approach 1:
The patent applies preliminary action by having user equipment insert delay information into their random access signals. This delay information is inserted in advance and allows the base station to pre-determine which sequence set to search, eliminating the need for exhaustive sequence searching and reducing computational load
4Loss of time
If all users use the same sequence set, then access latency is reduced, but path loss and frequency offset variations cannot be addressed
Solution Approach 1:
The patent implements local quality by assigning different sequence sets to users based on their location within the cell. Users experiencing different path loss and frequency offset conditions are assigned appropriate sequence sets that optimize their random access performance for their specific channel conditions
Solution Approach 2:
The patent introduces dynamics by enabling users to select sequence sets based on their current channel conditions and location. The system dynamically adapts sequence allocation to user needs rather than using a static uniform assignment, improving both adaptability and access efficiency
Data Source
AI summary
A segmented access based signal transmitting/receiving method and a sequence allocating method for the same are disclosed. According to one embodiment of the present invention, a method of transmitting a signal of a user equipment in a communication system includes selecting a channel in accordance with at least one selected from the group consisting of a signal attenuation extent of a downlink signal to the user equipment and a speed of the user equipment from channels differently provided based on at least one selected from the group consisting of the signal attenuation extent of the downlink signal and the speed of the user equipment and transmitting the signal using the selected channel.