Radio Channel Preamble Cyclic Shift Selection for Cell Size
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Solution Overview
Problem
Current cellular radio systems face challenges in synchronizing uplink timing due to unknown round-trip propagation delays, leading to inefficient Random Access (RA) procedures and limited support for cell sizes, as the number of preambles derived from a single root sequence is cell-size dependent, restricting the effective cell size and increasing interference.
Innovation Solution
Introducing multiple sets of basic cyclic shift values, where the preamble format acts as a selector for the appropriate set, allowing for a higher granularity of cyclic shift lengths and increasing the number of orthogonal preambles, thereby supporting larger cell sizes and reducing interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single set of basic cyclic shift values is used for all preamble formats, then the system is simple to implement, but the number of orthogonal preambles is limited and cell size support is restricted
Solution Approach 1:
The patent divides the single set of basic cyclic shift values into multiple sets, where each set is associated with specific preamble formats. This segmentation allows different cyclic shift values to be used depending on the cell size and preamble format, thereby increasing the number of orthogonal preambles and improving cell size support without significantly increasing system complexity.
Solution Approach 2:
The patent introduces dynamic selection of basic cyclic shift value sets based on the preamble format being used. The system can adaptively choose the appropriate set of cyclic shift values according to the specific RA preamble format, enabling flexible support for different cell sizes and improving overall system adaptability.
2Reliability
If the cyclic prefix and guard period are increased to support larger cell sizes, then the timing uncertainty is covered, but the preamble length increases and received energy is diluted
Solution Approach 1:
The patent changes the parameter of basic cyclic shift values based on the preamble format and cell size requirements. By selecting appropriate cyclic shift values from different sets, the system can maintain proper timing separation for large cell sizes without necessarily increasing the cyclic prefix or guard period duration, thus avoiding preamble length extension and energy dilution.
3Productivity
If more RA preambles are provided to reduce collisions, then the probability of successful access increases, but the number of root sequences required increases system complexity
Solution Approach 1:
The patent applies different basic cyclic shift values from different sets to different preamble formats based on local requirements (cell size, timing uncertainty). This allows the system to generate more orthogonal preambles from the same root sequences by utilizing different cyclic shift patterns, thereby increasing the number of available preambles without proportionally increasing the number of root sequences required.
Data Source
AI summary
The invention relates to methods and communication devices for transmitting data on a radio channel comprising the steps of determining a first preamble format to be used in a cell of the second communication device, determining a basic cyclic shift value from a set of basic cyclic shift values, the set is selected based on the preamble format, and transmitting data comprising indication of the determined first preamble format and a basic cyclic shift value pointer indicating the basic cyclic shift value in the set of basic cyclic shift values.