Dual Preamble Sequence for LTE Random Access Collision Reduction
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Solution Overview
Problem
The scalability of LTE radio access systems is limited due to increased preamble collision events in massive machine communication scenarios, where machine devices transmit small payload messages, leading to inefficient signaling overhead and difficulty in detecting collisions in uplink random access channels.
Innovation Solution
A primary radio communications device determines a primary preamble sequence with specific properties and a secondary preamble sequence with associated properties, transmitting both to a secondary radio communications device, thereby enlarging the preamble space, reducing collision probability, and enabling multi-user detection without additional radio resources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the number of devices is increased for massive machine communication, then the network capacity and coverage are improved, but the number of preamble collision events increases and detection becomes difficult
Solution Approach 1:
The preamble is segmented into two distinct sequences: a primary preamble sequence transmitted on physical random access channel (PRACH) and a secondary preamble sequence transmitted on physical uplink shared channel (PUSCH). This segmentation allows the system to maintain the original random access function while adding a complementary detection mechanism that reduces collision impact.
Solution Approach 2:
The secondary preamble sequence acts as an intermediary element that provides additional detection capability. When primary preamble collisions occur, the secondary sequence serves as a mediator that enables the network to identify and handle colliding users through multi-user detection techniques.
2Device complexity
If traditional single preamble sequence is used, then the signaling overhead is simple, but the collision probability increases and multi-user detection is not possible
Solution Approach 1:
The patent merges two preamble transmission mechanisms into a unified random access procedure. The primary and secondary preamble sequences are combined in such a way that they work together to provide both initial access and collision detection capabilities, enabling multi-user detection without requiring completely separate access procedures.
Solution Approach 2:
The dual preamble sequence structure provides multi-functionality: the primary sequence handles initial random access signaling while the secondary sequence enables collision detection and multi-user detection. This universal structure serves multiple purposes within a single random access framework.
3Quantity of substance
If existing radio resources are used without additional resources, then the resource efficiency is maintained, but the preamble space is limited and collision probability increases
Solution Approach 1:
The patent introduces a new dimension to preamble transmission by utilizing different physical channels (PRACH and PUSCH) for primary and secondary sequences. This dimensional change in resource usage effectively expands the preamble space without requiring additional radio resources, as the same resources serve dual purposes.
Data Source
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AI summary
It is proposed a primary radio communications device (T1; T2), especially a terminal, for a radio communications network (2), the primary radio communications device (T1; T2) is configured to: determine (100; 200) a primary preamble sequence (ps1; ps1a; ps1b) with a first sequence property; determine (102; 202) a secondary preamble sequence (ps2; ps2a; ps2b) with a second sequence property being different from the first sequence property; and transmit (104; 204) a preamble (p; pa; pb) comprising the primary preamble sequence (ps1; ps1a; ps1b) and the secondary preamble sequence (ps2; ps2a; ps2b) to a secondary radio communications device (BS), especially a base station.