Scheduling Forward Data Bursts in CDMA2000 Networks
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Solution Overview
Problem
CDMA2000 wireless networks face complexity in scheduling high-speed data bursts due to limited radio resources, leading to inefficient resource allocation and fragmentation, resulting in low-speed bursts and high processing power requirements.
Innovation Solution
Provisioning permanent virtual pipes with contiguous resources at base stations to manage high-speed data transmissions, scheduling bursts in a round-robin fashion across these pipes to achieve fairness and reduce processing overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If resources are divided into smaller pools and distributed amongst multiple mobile terminals, then more mobile terminals can be serviced simultaneously, but the data rate per terminal decreases and processing power requirements increase
Solution Approach 1:
The patent segments the high-speed data channel into multiple virtual pipes of different widths (rates). Each virtual pipe can be independently allocated to mobile terminals, allowing the system to serve multiple terminals simultaneously while maintaining high data rates on each pipe. The segmentation is done in the logical layer rather than physically dividing the radio resources.
Solution Approach 2:
The patent introduces a new dimension of resource allocation by creating virtual pipes with different widths (data rates). Instead of simply dividing resources into equal smaller portions, the system creates a multi-dimensional resource space where pipes of varying capacities can be assigned based on terminal needs and channel conditions, thereby maintaining high productivity while increasing quantity of serviced terminals.
2Productivity
If resources are continuously re-allocated to new burst requests, then resource utilization improves, but processing complexity and overhead increase significantly
Solution Approach 1:
The patent performs preliminary allocation of virtual pipes before actual data transmission. The base station pre-establishes multiple virtual pipes with different widths and assigns them to mobile terminals in advance based on predicted traffic patterns and channel conditions. This preliminary action reduces the need for continuous real-time re-allocation during active transmission, thereby reducing processing complexity while maintaining good resource utilization.
Solution Approach 2:
The patent implements dynamic virtual pipe management where the system can adjust the number and width of active virtual pipes based on current system load and traffic demands. When traffic is light, fewer wider pipes are used; when traffic increases, more pipes or narrower pipes are activated. This dynamic adaptation allows the system to maintain efficiency across varying load conditions without excessive processing overhead.
3Productivity
If permanent dedicated channels are used for high-speed data transmission, then data rate is maintained, but radio resource availability for multiple terminals is limited
Solution Approach 1:
The patent makes the high-speed data channel universal by creating virtual pipes that can be dynamically assigned to multiple different mobile terminals based on need. Instead of dedicating fixed radio resources to specific terminals, the same physical radio resources can support multiple virtual pipes that are allocated to different terminals at different times, allowing the system to maintain high data rates while serving more terminals through time- and rate-division multiplexing.
Data Source
AI summary
In a 3G CDMA2000 network, permanent virtual pipes of different data rates (153.6 kbps, 76.8 kbps, 38.4 kbps and 19.2 kbps, for example) are provisioned at a base station on the Forward Supplemental Channel (F-SCH) for the transmission of data bursts to requesting mobile terminals by allocating and grouping together a set of resources (i.e., contiguous Walsh codes, contiguous ASIC real estate, etc.). Data bursts arriving from the network are scheduled onto timeslots on all the pipes in a manner such that at least one burst segment of each active burst is scheduled into a timeslot on the highest data rate pipe. The other burst segments of a burst are scheduled onto all the pipes so they migrate through the various rate pipes in order to give all bursts opportunities on the higher rate pipes.