Random Access Message Transmission Using Spreading Codes
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Solution Overview
Problem
In wireless communication systems, multiple user equipment (UEs) attempting to connect to a network simultaneously experience collisions during random access message transmission, leading to inefficient access procedures and communication delays due to the inability of base stations to distinguish between overlapping messages.
Innovation Solution
UEs transmit random access messages using multiple symbols with repetitions of a random access sequence weighted by different elements of a spreading code, allowing for differentiation and reducing collisions by using unique spreading codes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple UEs transmit random access messages simultaneously using traditional methods, then the network can receive more access requests, but message collisions increase and prevent successful identification of UEs
Solution Approach 1:
The random access message is segmented into multiple repetitions transmitted across different time symbols. Each repetition is weighted by different elements of a spreading code, allowing the base station to reconstruct the original message even if some repetitions collide with other UEs' messages. This segmentation transforms a single vulnerable transmission into multiple recoverable segments.
Solution Approach 2:
The patent changes the parameter of message transmission by applying spreading codes (weighting factors) to different message repetitions. Instead of transmitting identical unweighted repetitions, each repetition is modified by multiplying with corresponding spreading code elements, enabling the base station to distinguish between simultaneous transmissions from different UEs through correlation processing.
2Device complexity
If random access messages are transmitted using single symbol traditional methods, then the transmission structure is simple, but collisions cannot be distinguished and cause access delays
Solution Approach 1:
The UE performs preliminary actions by pre-multiplying message repetitions with spreading code elements before transmission. This preprocessing ensures that when messages are received at the base station, the spreading code structure is already embedded in the transmitted signal, enabling faster correlation-based identification and reducing access delay without requiring complex post-processing at the UE side.
3Reliability
If random access sequences are repeated without weighting, then transmission robustness improves, but ability to distinguish simultaneous messages from different UEs decreases
Solution Approach 1:
Different local qualities are applied to different message repetitions through spreading code weighting. Instead of uniform unweighted repetitions, each repetition position in the time sequence is assigned a specific weighting factor from the spreading code. This creates local variations that enable the base station to distinguish between simultaneous transmissions from different UEs while maintaining overall transmission robustness through the repeated structure.
Data Source
AI summary
A user equipment (UE) may transmit a random access message to a wireless node using multiple symbols. The random access message may include repetitions of a random access sequence weighted by a spreading code. For example, a random access sequence may be weighted using different elements of the spreading code, where a first repetition may be weighted with a first element and a second repetition may be weighted using a second element. The weighted random access signals may be spread over multiple symbols and transmitted to the wireless node as the random access message. In some cases, a spreading code may include values of one and negative one, may be based on rows of a Hadamard matrix, or may correspond to a number of symbols used to transmit the random access message.