E-RACH Resource Signaling via AICH Signature Segmentation

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Solution Overview

Problem

The existing mechanisms for E-RACH access in UMTS WCDMA systems face challenges such as increased collision probability due to limited AICH signature space, which affects both R99 RACH and E-RACH, and require more accurate signature amplitude detection, while also impacting legacy UE detection probabilities.

Innovation Solution

The method involves signaling E-DCH resources independently from the acknowledgement indication, using a subset of AICH signatures to indicate resource sets, and associating each E-RACH preamble with a specific E-DCH resource, allowing for reduced signaling and interference, and configuring E-RACH and E-DCH resources into subsets to balance collision and blocking probabilities.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If multiple AICH signatures are mapped to each preamble to indicate E-DCH resources, then resource allocation capability is improved, but collision probability increases and detection accuracy deteriorates

Engineering Contradiction:

Improveresource allocation capabilityVSAvoidcollision probability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent divides the AICH signature space into multiple subsets, where each subset is dedicated to indicating a specific E-DCH resource parameter. This segmentation allows independent indication of multiple resources without requiring all signatures to be transmitted simultaneously, thereby reducing collision probability while maintaining resource allocation capability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces a new dimension for resource indication by using the absence or presence of signatures (rather than just signature values) to encode resource allocation information. This dimensional expansion allows more efficient use of the signature space and reduces the need for multiple simultaneous signature transmissions.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Adaptability or versatility

If multiple AICH signatures are transmitted to indicate E-DCH resources, then resource allocation capability is improved, but signature amplitude detection accuracy deteriorates

Engineering Contradiction:

Improveresource allocation capabilityVSAvoidsignature amplitude detection accuracy

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent extracts the resource indication function from the amplitude detection process by using the presence/absence of signatures rather than relying on amplitude variations. This separation allows legacy UEs to continue using amplitude detection for R99 RACH while E-RACH UEs use signature presence for resource indication.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces an intermediary mechanism where the Node B selectively transmits or withholds signatures based on resource allocation decisions. This intermediary approach allows resource indication without requiring legacy UEs to detect multiple signatures, thus maintaining detection accuracy for both R99 and E-RACH.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If the number of AICH signatures is increased to reduce collision probability, then access reliability is improved, but legacy UE detection probability deteriorates

Engineering Contradiction:

Improveaccess reliabilityVSAvoidlegacy UE detection probability

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The patent applies different signature usage strategies to different UE types: legacy UEs continue to use the existing amplitude detection mechanism for R99 RACH, while E-RACH UEs utilize the new signature presence/absence mechanism. This local differentiation allows both UE types to operate optimally without interfering with each other's detection accuracy.

Inventive Principle:

Principle #3Local quality

4Productivity

If E-DCH resources are indicated using existing AICH signatures, then signaling efficiency is improved, but resource allocation flexibility is reduced

Engineering Contradiction:

Improvesignaling efficiencyVSAvoidresource allocation flexibility

Core Design Contradiction:

ProductivityVSAdaptability or versatility

Solution Approach 1:

The patent makes the AICH signatures serve multiple functions: they continue to acknowledge R99 RACH preambles for legacy UEs while simultaneously indicating E-DCH resource allocations for E-RACH UEs. This multi-functionality achieves both signaling efficiency and resource allocation flexibility without requiring separate signaling channels.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS9497777B2Indicating E-DCH resources for E-RACH

Publication Date: 2016.11.15 KONINKLIJKE PHILIPS NV

AI summary

In UMTS WCDMA a new RACH-based uplink is being discussed. The request for uplink transmission resource is made using a mechanism based on the conventional RACH. The main difference from the conventional RACH is that the data transmission uses a high-speed uplink packet data channel, known as Enhanced Dedicated Channel (E-DCH), instead of a single short message associated directly with the RACH preamble. One proposed scheme for indicating the E-DCH resources to be used creates a link between the values of each of a group of multiple signatures sent on the AICH (to acknowledge the E-RACH access) and a specific set of E-DCH parameters defined in a table. We propose to signal the set of resources to be used independently from acknowledging the E-RACH access. One possible method is to transmit information in the unused portion of the AICH (corresponding to 1024 chips every slot) indicating the resource set.