HSDPA Handover via Simultaneous HS-SCCH Reception
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Solution Overview
Problem
In HSDPA communication systems, handovers between base stations result in communication interruptions due to the inability to synchronize data transmission timing, leading to unnecessary stoppages even when base stations' timing is synchronized, and existing methods using reception quality to select the next base station still generate useless interruption times.
Innovation Solution
A mobile communication system that allows continuous HSDPA communication by enabling the mobile terminal to receive HS-SCCH signals from both the source and destination base stations simultaneously, with up to four signals, and perform handover without stopping, by aligning transmission timings and using despreading sections to manage signal reception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If hard handover is performed in HSDPA communication, then the mobile terminal can switch between base stations, but the communication is interrupted during handover
Solution Approach 1:
The mobile terminal receives and buffers HS-SCCH signals from both the source base station and destination base station simultaneously before completing the handover. This preliminary reception of signals from both stations allows the terminal to prepare for the transition without interrupting the ongoing communication, thereby eliminating the communication interruption that occurs in traditional hard handover.
Solution Approach 2:
The handover process is designed to maintain continuous reception of HS-SCCH signals from base stations throughout the transition. By enabling the mobile terminal to receive signals from multiple base stations concurrently and maintain communication continuity during the handover process, the system eliminates the stoppage time inherent in traditional hard handover while ensuring seamless base station switching.
2Loss of time
If the mobile terminal receives HS-SCCH signals from multiple base stations simultaneously, then handover can be performed without communication stop, but the number of signals to be processed increases
Solution Approach 1:
The mobile terminal maintains a buffer to temporarily store received HS-SCCH signals from multiple base stations. When the number of simultaneously receivable signals reaches the maximum limit of four, the terminal discards older buffered signals and recovers by accepting new signals from the current active base stations. This buffering mechanism allows continuous signal reception during handover without overwhelming the processing capacity.
Solution Approach 2:
The mobile terminal dynamically adjusts the number of HS-SCCH signals it processes based on the handover state. During normal operation, it processes signals from one base station; during handover, it simultaneously processes signals from multiple base stations up to the maximum of four. This dynamic adaptation allows the system to handle increased signal processing demands only when necessary, minimizing overall device complexity.
Data Source
AI summary
A mobile communication system includes a plurality of base station apparatuses; and a mobile terminal configured to perform HSDPA (High Speed Downlink Packet Access) communication between the mobile terminal and the plurality of base station apparatuses. The mobile terminal has a receiving section configured to receive HS-SCCH (High Speed Shared Control Channel) signals from the base station apparatus as a source of handover and the base station apparatus as a destination of the handover at a same time.