Contention-Free Handoff Return in Wireless Networks

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Solution Overview

Problem

In wireless communication networks, handoff processes often result in signal collisions and delays due to the use of contention-based preambles, which can disrupt continuous service when devices move between cell coverage areas.

Innovation Solution

The implementation of a contention-free handoff return method in wireless networks, where an enhanced Node B (eNB) obtains and provides pre-handoff and post-handoff contention-free (CF) preambles to User Equipment (UE), enabling seamless communication transitions without signal collisions, by comparing signal strengths and determining similarity ranges for efficient handoff and return processes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If contention-based preambles are used during handoff, then devices can access communication services, but signal collisions and delays occur disrupting continuous service

Engineering Contradiction:

Improvecontinuous serviceVSAvoidhandoff delay

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The source eNB allocates a dedicated CF preamble to the UE before the handoff is executed. This preliminary allocation ensures that when the UE needs to access the target eNB during handoff, it can use the pre-assigned preamble without contention, eliminating delays and signal collisions that would otherwise occur with contention-based preambles.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If contention-based preambles are used during handoff, then devices can access communication services, but signal collisions occur disrupting continuous service

Engineering Contradiction:

Improvecontinuous serviceVSAvoidsignal collision

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The source eNB acts as an intermediary by allocating a dedicated CF preamble to the UE before handoff. This intermediary action provides the UE with a unique identifier that it can use to access the target eNB without contention, eliminating signal collisions that would occur with contention-based preambles while maintaining continuous service.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If CF preambles are allocated for handoff return, then service interruption is prevented, but network signaling complexity increases

Engineering Contradiction:

Improveservice continuityVSAvoidhandoff signaling

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The source eNB allocates both pre-handoff CF preambles (for initial handoff) and post-handoff CF preambles (for potential return) to the UE in advance. This preliminary allocation of both preambles before handoff execution ensures that the UE can seamlessly return to the source eNB if needed, preventing service interruption while the signaling complexity is managed through automated network procedures.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS9277465B1Contention-free handoff return in a wireless network

Publication Date: 2016.03.01 T MOBILE INNOVATIONS LLC

AI summary

A first enhanced Node B (eNB) and method for contention-free handoff return in a wireless network are provided. The first eNB in one example embodiment includes a transceiver system configured to communicate with a User Equipment (UE) and a processing system coupled to the transceiver system and configured to receive signal strength information from the UE, with the processing system being further configured to obtain a pre-handoff CF preamble for handoff of the UE from the first eNB to the second eNB, provide the pre-handoff CF preamble to the UE, generate a post-handoff CF preamble for the UE where the UE can use the post-handoff CF preamble to return from the second eNB to the first eNB, and provide the post-handoff CF preamble to the UE.