Traffic Channel Setup Latency Reduction via Control Subchannel Splitting
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Solution Overview
Problem
In wireless telecommunications systems, particularly in CDMA communications, there is a latency issue due to the time required for channel code reassignment and acknowledgment processes, which delays data packet reception and increases response time.
Innovation Solution
The system pipelines channel code assignments from a base transceiver station to mobile units, splits control channels into subchannels, staggers forward and reverse traffic channels by half an epoch, and eliminates redundant acknowledgments to reduce latency, allowing data transmission to start within two epochs after channel assignments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If PN codes are reassigned to different user connections, then channel allocation flexibility is improved, but packet latency increases due to code demodulator lock-in time
Solution Approach 1:
The system performs preliminary actions by pre-configuring code demodulators with multiple PN codes before actual channel reassignment occurs. When a code reassigned is needed, the demodulator already has the necessary code information prepared, eliminating the need to wait for code lock-in during data transmission. This preliminary preparation allows immediate switching between different PN codes without latency penalty.
2Reliability
If channel setup messages are processed completely before data transmission, then channel configuration reliability is improved, but response time increases
Solution Approach 1:
The base station processor performs preliminary processing of channel setup messages by pre-configuring the code demodulators with necessary PN code information before actually starting data transmission. This allows the system to maintain configuration reliability through proper initialization while reducing response time because the demodulators are already ready to receive and process data immediately upon channel activation, without waiting for post-initiation processing.
Solution Approach 2:
The system maintains continuity of useful action by keeping code demodulators in a ready state with pre-loaded PN codes, allowing immediate transition from channel setup to data transmission without interruption. The demodulators continuously prepare and wait for data packets without idle processing time, ensuring continuous productive operation from channel activation through data reception.
3Reliability
If acknowledgment messages are sent for every channel allocation, then channel setup reliability is improved, but system complexity increases
Solution Approach 1:
The system extracts and removes redundant acknowledgment messages from the channel setup protocol. By taking out these unnecessary acknowledgment steps, the patent simplifies the overall system complexity while maintaining sufficient reliability through alternative confirmation mechanisms that don't require explicit acknowledgment message exchange for every channel allocation.
Data Source
AI summary
A control channel supporting traffic control in epochs is divided into two control subchannels each being less than or equal to about a half epoch in duration and occurring serially in time. Slot allocation data may be transmitted and received independently over the subchannels. One subchannel may be used for transmitting forward slot allocation data and the other subchannel may be used for transmitting reverse slot allocation data. The channel split into two subchannels may be a paging channel. The forward and reverse slot allocation data may be transmitted between a base station processor and field unit. Forward and reverse traffic data may be staggered by at least about half an epoch. Transmission of traffic data happens within about two epochs after the assignments.