Wireless Handoff Using Intra-Frequency Cell Measurement
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Solution Overview
Problem
Current wireless communication devices face inefficiencies in measuring and handing off to other base stations, as they must retune for different frequencies and perform time-consuming processes like waiting for time offsets, leading to increased communication time and decreased throughput.
Innovation Solution
The wireless communication device measures only nearby base stations on the same frequency as the current base station, estimates its location based on receive power, and initiates handoffs without waiting for acknowledgement signals or time offsets, using previously measured time offsets to reduce latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the wireless communication device measures all cells within range, then measurement completeness is improved, but communication time is lost due to retuning for different frequencies
Solution Approach 1:
The patent extracts and prioritizes only the most relevant cells for measurement based on proximity and frequency matching. Instead of measuring all cells within range, the device identifies and focuses on nearby cells operating on the same frequency as the current base station, eliminating unnecessary retuning operations while maintaining measurement effectiveness for handoff decisions.
Solution Approach 2:
The patent applies local quality by differentiating measurement priorities based on cell characteristics. Cells are categorized into different measurement priorities: high priority for nearby same-frequency cells, medium priority for nearby different-frequency cells, and low priority for distant cells. This localized quality assignment optimizes measurement resources by concentrating efforts on the most relevant cells for potential handoffs.
2Manufacturing precision
If the wireless communication device waits for time offset from new base station, then handoff accuracy is improved, but handoff latency increases by up to 10 ms
Solution Approach 1:
The patent performs preliminary measurements of time offsets during the cell measurement phase, before the actual handoff is triggered. The device continuously monitors and stores time offset information from neighboring base stations in advance, so that when a handoff is needed, the pre-measured time offset can be immediately utilized without waiting for new measurements or acknowledgments, significantly reducing handoff latency.
Solution Approach 2:
The patent enables the device to skip the traditional waiting period for time offset confirmation from the new base station. By using pre-measured time offset values and making handoff decisions based on current signal conditions, the device rushes through the handoff process more quickly, accepting a calculated risk that can be managed through continuous monitoring and rapid fallback capabilities.
3Adaptability or versatility
If the wireless communication device performs unorganized PLMN search, then network compatibility is improved, but system performance deteriorates due to significant time consumption
Solution Approach 1:
The patent performs preliminary PLMN identification during the cell measurement and evaluation phase. Before initiating a full PLMN search, the device checks whether the target cell's PLMN is already known or previously identified, allowing for rapid handoff decisions when PLMN information is available and avoiding time-consuming searches when unnecessary.
Solution Approach 2:
The patent implements a dynamic PLMN search strategy that adapts to current network conditions. The device adjusts the thoroughness of PLMN searching based on factors such as signal strength, cell priority, and existing PLMN knowledge. When conditions favor rapid handoff, the search is minimized; when network compatibility is uncertain, more comprehensive searching is performed, optimizing the balance between compatibility and performance.
Data Source
AI summary
A wireless communication device is disclosed that is capable of performing efficient handoffs in order to maximize connection time with either a serving or target base station. The wireless communication device performs measurements of only intra-frequency base stations to avoid retuning its radio module. Based on this information, as well as stored information relating to nearby base stations, the serving base station is able to estimate a position of the wireless communication device and compare the estimated position to positions of the known base stations in order to make a handoff decision. In addition, by storing information during measurement or handoff preparation, the device is capable of skipping handoff steps, immediately return to the serving base station after handoff failure, and/or perform streamlined PLMN searching.