Wireless Handover Without Random Access Channel
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Solution Overview
Problem
Current wireless communication systems face inefficiencies in handover processes, particularly in LTE networks, where the random access channel (RACH) becomes over-utilized, leading to challenges in seamlessly transferring communications between base stations without causing timing errors.
Innovation Solution
The method involves obtaining semi-static information such as timing advance (TA) and channel quality indicator (CQI) from target base stations using sounding reference signals (SRS), allowing mobile devices to handover without relying on the RACH by utilizing assigned uplink control channels and strategically choosing time intervals with longer cyclic prefixes to account for timing errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the random access channel (RACH) is used for handover requests, then mobile devices can request and schedule resources for handover, but the RACH becomes over-utilized leading to increased congestion and reduced handover efficiency
Solution Approach 1:
The patent applies preliminary action by having the mobile device obtain semi-static information (timing advance and CQI) from target base stations in advance before actual handover occurs. The device performs measurements and resource acquisition on target cells during idle periods, so that when handover is needed, the necessary resources and timing information are already prepared, eliminating the need to use RACH for handover resource scheduling.
Solution Approach 2:
The patent introduces uplink control channels as an intermediary mechanism between the mobile device and target base station. Instead of using RACH directly for handover, the device uses assigned uplink control channels to transmit scheduling requests to multiple target base stations simultaneously, thereby mediating the handover process and reducing RACH congestion.
2Reliability
If the mobile device obtains timing advance and CQI information from target base stations, then handover can proceed without using RACH, but the device must manage multiple uplink control channels and timing synchronization
Solution Approach 1:
The patent applies segmentation by dividing the handover process into distinct phases: (1) obtaining semi-static information (timing advance and CQI) from target base stations, (2) selecting appropriate time intervals with longer cyclic prefixes for resource acquisition, and (3) executing handover using the prepared resources. This segmentation allows the device to manage complexity systematically by handling one aspect at a time.
Solution Approach 2:
The patent utilizes parameter changes by strategically selecting time intervals with longer cyclic prefixes to account for timing errors during handover. The device adjusts the cyclic prefix parameter dynamically based on the acquired timing advance information, allowing flexible adaptation to different synchronization conditions and improving handover reliability under varying network conditions.
3Measurement precision
If the device uses longer cyclic prefixes for timing error compensation, then timing accuracy is improved, but the time interval for resource acquisition is extended
Solution Approach 1:
The patent applies periodic action by having the mobile device periodically monitor and measure timing information from target base stations during idle periods. The device performs measurements at regular intervals to accumulate sufficient timing advance and CQI information, allowing efficient resource acquisition when handover is needed while maintaining timing accuracy through continuous periodic monitoring.
Data Source
AI summary
Systems and methodologies are described that facilitate handing over mobile device communications in a wireless network from a source base station to a target base station without using a random access channel (RACH). In this regard, the mobile device can monitor multiple base stations determining timing information related thereto and access scheduling request channels for the base stations. When ready for handover, the mobile device can request data resources over the scheduling request channel using the appropriate timing information.