Wireless Handover Schemes for Latency and Reliability
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Solution Overview
Problem
Current wireless communication systems, such as IEEE 802.16m, face challenges in handover latency and reliability due to fluctuations in channel conditions and the need for efficient resource allocation and power control in multi-BS environments, particularly for supporting advanced services and applications like those described in ITU Report ITU-R M.2072.
Innovation Solution
The implementation of enhanced handover schemes, including soft handover and enhanced fast base station switching, with multi-BS ranging mechanisms, distributed control channels, and power control schemes to reduce latency and improve reliability, along with efficient neighbor BS system configuration information transmission to facilitate seamless transitions and resource management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If fast base station switching is implemented, then handover speed is improved, but handover reliability deteriorates due to channel condition fluctuations
Solution Approach 1:
The patent implements preliminary actions by pre-configuring multiple base stations in the active set before handover occurs. The mobile station measures and reports on multiple base stations simultaneously, and the network pre-establishes connection parameters for candidate base stations. This allows the mobile station to quickly switch between pre-configured base stations without waiting for full setup during handover, thereby improving speed while maintaining reliability through pre-validated connections.
Solution Approach 2:
The patent changes key handover parameters dynamically based on channel conditions. The network adjusts handover thresholds, active set composition, and switching timing based on real-time signal strength measurements and quality indicators. By adaptively modifying these parameters rather than using fixed thresholds, the system achieves fast switching when conditions permit while avoiding unreliable switches when channel fluctuations occur.
2Reliability
If multi-BS ranging mechanisms are implemented, then handover reliability is improved, but system complexity increases
Solution Approach 1:
The patent merges multiple base station ranging operations into a unified process. Instead of performing separate ranging procedures with each base station individually, the system combines ranging measurements with multiple base stations into a single coordinated operation. The mobile station performs one ranging sequence that simultaneously evaluates multiple base stations, and the network aggregates the results to determine the optimal target. This merging approach improves reliability through comprehensive evaluation while reducing complexity by eliminating redundant procedures.
Solution Approach 2:
The patent implements a universal ranging mechanism that serves multiple functions simultaneously. The same ranging procedure used for measuring signal strength also evaluates channel quality, determines handover eligibility, and establishes connection parameters. This multi-functional approach eliminates the need for separate measurement and handover preparation procedures, thereby improving reliability through thorough assessment while reducing system complexity by consolidating operations.
3Productivity
If distributed control channels are implemented, then resource allocation efficiency is improved, but control signal overhead increases
Solution Approach 1:
The patent segments the control channel into multiple distributed sub-channels, each serving a specific base station or cell region. Instead of using a single centralized control channel that must serve the entire network, the system divides control signaling into smaller, localized segments. This allows more efficient resource allocation within each segment while reducing the total overhead by eliminating redundant control signals across different regions. Mobile stations receive control information only from relevant segments, reducing unnecessary processing and signal traffic.
4Loss of time
If neighbor BS system configuration information is transmitted efficiently, then handover latency is reduced, but information transmission reliability may deteriorate
Solution Approach 1:
The patent implements preliminary transmission of neighbor base station configuration information during network entry or initial connection establishment. Rather than waiting for handover decisions to trigger configuration requests, the system pre-downloads and caches configuration parameters for multiple neighbor base stations. This allows the mobile station to immediately access configuration data when handover becomes necessary, significantly reducing handover latency. The preliminary action ensures that critical information is already available and validated, maintaining transmission reliability while eliminating delays associated with real-time configuration requests.
Data Source
AI summary
One method of wireless communication involves acknowledging that an anchor base station received a handover indication signal. Another method involves: receiving, from base stations of an active set, offset signals identifying a respective differences in time between a reference time and respective times when the base station received a ranging signal from a mobile station; and transmitting, to the mobile station, a ranging control signal in response to the respective offset signals. Another method involves transmitting, to a mobile station in response to an active set signal, a system configuration information signal including system configuration information of a base station in an active set. Another method involves determining an uplink control channel power parameter in response to channel condition signals received from base stations in an active set. Another method involves transmitting a control signal to base stations in an active set on respective control channels. Apparatuses are also disclosed.