CDMA Supplemental Channel Scheduling via Segmented Rate Assignment
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Solution Overview
Problem
Current cellular communication systems face inefficiencies in managing shared channel resources, particularly in CDMA systems, leading to reduced throughput due to varying requested rates and congested base stations, especially during soft handoff conditions, which affects both data and voice communications.
Innovation Solution
The implementation of a 'fire and forget' scheduling method and a request/response type method for allocating time slices and rates in CDMA networks, where the primary base station allocates resources without waiting for secondary links' responses, and a fairness method to ensure equitable resource distribution based on signal strength and power constraints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the base station transceiver searches for the highest channel rate available by negotiating with multiple base station transceivers, then the data transmission rate is improved, but the negotiation overhead and system complexity increase significantly
Solution Approach 1:
The patent segments the channel allocation process into two independent phases: rate determination (based on mobile station capability and service requirements) and time slice assignment (performed separately by each base station transceiver). This segmentation eliminates the need for multiple transceivers to negotiate and reach consensus on the transmission rate, as each transceiver independently assigns time slices based on pre-determined rate parameters.
Solution Approach 2:
The mobile station's maximum data rate capability and service requirements are determined in advance before the actual channel allocation. This preliminary determination of transmission rate parameters allows base station transceivers to independently perform time slice assignment without needing to negotiate rates with each other, thereby reducing negotiation overhead while maintaining high data transmission rates.
2Reliability
If the base station negotiates common rate and time slice among several base station transceivers, then resource coordination is improved, but the throughput is severely impacted by the weakest or most congested base station
Solution Approach 1:
The patent extracts the rate determination function from the time slice assignment process. The transmission rate is determined by the mobile station's capability and service requirements, independent of individual base station transceiver availability. Each base station transceiver then independently assigns time slices based on this pre-determined rate, allowing the system to achieve resource coordination without being constrained by the weakest base station's negotiation position.
Solution Approach 2:
The system performs preliminary determination of the transmission rate based on mobile station capability and service requirements before time slice assignment. This allows each base station transceiver to independently assign time slices at the determined rate without needing to negotiate with other transceivers, thereby maintaining resource coordination reliability while avoiding throughput limitations imposed by the weakest base station.
3Reliability
If the base station allocates supplemental channel resources based on user's subscribed rate and current message flow backlog, then service quality is improved, but TCP throughput is significantly reduced due to varying requested rates
Solution Approach 1:
The patent implements a feedback mechanism where the mobile station reports its maximum data rate capability and service requirements to the base station. The base station uses this feedback to determine an appropriate transmission rate that balances service quality requirements with TCP throughput stability. This feedback-driven rate determination prevents excessive rate variations that would cause TCP to reduce throughput, while still allocating supplemental channel resources according to service quality needs.
Solution Approach 2:
The system dynamically adjusts the transmission rate parameter based on mobile station capability feedback and service requirements, rather than strictly following the user's subscribed rate. This parameter adjustment allows the base station to allocate supplemental channel resources in a manner that maintains service quality while avoiding rate variations that would negatively impact TCP throughput performance.
Data Source
AI summary
A method (30) schedules the utilization of the supplemental channel of a base station transceiver (20-25). This scheduling includes time slot assignment as well as data transfer rate per time slot. One method simply selects the next time slot with a maximum rate for the primary base station transceiver (130). The method then selects the same time slot for each of the secondary links with the secondary base stations (132). The data is then simply sent to each of the BTSs (20-25) for transmission to the mobile station (10). In another alternative, a request is made for a supplemental channel usage for the primary link (144). Then secondary links are selected for transmission to the mobile station (10) only if they provide additional diversity gain (148) and resources are available at the secondary link BTSs.