PRACH Signals with Different Bandwidths for Random Access

Solution Overview

Problem

The existing LTE random access procedure in radio communication networks faces challenges in sustaining higher path loss, as increasing the bandwidth of the Physical Random Access Channel (PRACH) signal to overcome path loss results in unreasonable resource allocation and is not beneficial for power-limited user equipment (UEs).

Innovation Solution

Transmitting two PRACH signals with different frequency bandwidths, where the first signal has a narrower bandwidth for energy concentration and the second signal has a wider bandwidth for improved time-of-arrival estimation, potentially without receiving feedback from the radio network node, to enhance resource utilization during the random access procedure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the bandwidth of the PRACH signal is increased to overcome path loss, then the signal can sustain higher path loss, but this results in unreasonable resource allocation and is not beneficial for power-limited user equipment

Engineering Contradiction:

Improvepath loss sustainabilityVSAvoidresource allocation

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The PRACH signal transmission is segmented into two distinct parts: a first PRACH signal with narrower bandwidth for initial access and energy concentration, and a second PRACH signal with wider bandwidth for improved time-of-arrival estimation. This segmentation allows each signal to serve its specific purpose optimally without the drawbacks of continuously using wide bandwidth

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different bandwidth characteristics are applied to different parts of the random access procedure. The first PRACH signal uses narrower bandwidth concentrated at a specific frequency resource, while the second PRACH signal uses wider bandwidth. This local quality differentiation optimizes resource usage at each stage of the access procedure

Inventive Principle:

Principle #3Local quality

2Reliability

If the bandwidth of the PRACH signal is increased to overcome path loss, then the signal can sustain higher path loss, but this is not beneficial for power-limited user equipment

Engineering Contradiction:

Improvepath loss sustainabilityVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The PRACH signal transmission is segmented into two distinct parts: a first PRACH signal with narrower bandwidth for initial access and energy concentration, and a second PRACH signal with wider bandwidth for improved time-of-arrival estimation. This segmentation allows each signal to serve its specific purpose optimally without the drawbacks of continuously using wide bandwidth

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different bandwidth characteristics are applied to different parts of the random access procedure. The first PRACH signal uses narrower bandwidth concentrated at a specific frequency resource, while the second PRACH signal uses wider bandwidth. This local quality differentiation optimizes resource usage at each stage of the access procedure

Inventive Principle:

Principle #3Local quality

3Device complexity

If a single PRACH signal is transmitted, then the procedure is simple, but accurate timing alignment and resource optimization are difficult to achieve

Engineering Contradiction:

Improveprocedure simplicityVSAvoidtiming alignment accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The PRACH signal transmission is segmented into two distinct parts: a first PRACH signal with narrower bandwidth for initial access and energy concentration, and a second PRACH signal with wider bandwidth for improved time-of-arrival estimation. This segmentation allows each signal to serve its specific purpose optimally without the drawbacks of continuously using wide bandwidth

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The first PRACH signal with narrower bandwidth is transmitted first to establish initial connection and concentrate energy for detection. Based on the outcome of this preliminary action, the system then decides whether to transmit the second PRACH signal with wider bandwidth for more precise timing estimation, performing the more resource-intensive action only when necessary

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS9936523B2PRACH signals with different bandwidths

Publication Date: 2018.04.03 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

The present disclosure concerns radio communication. More particularly, the present disclosure concerns random access procedures used in communication between user equipments (UEs) and radio network nodes, such as evolved NodeB's. According to one exemplary embodiment disclosed herein, a method in a UE 10 comprises transmitting 110, 130 two or more Physical Random Access Channel, PRACH, signals, where the two or more PRACH signals have different frequency bandwidths. Hereby it is made possible to improve the resource utilization during the random access procedure.