SDMA Base Station Uplink Bandwidth Allocation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional wireless access networks face high overhead and latency due to bandwidth request collisions, which hinder efficient bandwidth allocation in broadband wireless access networks like WiMax.
Innovation Solution
The implementation of Space-Division Multiple Access (SDMA) techniques in base stations to differentiate orthogonal sequences from subscriber stations, allowing simultaneous bandwidth requests using disjoint pilot patterns and orthogonal frequency division multiple access (OFDMA), reducing collisions and latency by enhancing channel bandwidth and network throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional bandwidth request methods are used, then bandwidth allocation can be performed, but overhead consumption increases and latency increases due to collisions
Solution Approach 1:
The patent introduces spatial dimension through SDMA technology, allowing subscriber stations to transmit bandwidth requests simultaneously from different spatial locations. The base station uses multiple receive antennas to separate these simultaneous requests, transforming the traditional single-dimension (time/frequency) resource allocation into multi-dimensional allocation, thereby resolving the contradiction between allocation efficiency and latency.
2Productivity
If conventional bandwidth request methods are used, then bandwidth allocation can be performed, but overhead consumption increases
Solution Approach 1:
The patent merges multiple bandwidth request transmissions that would traditionally occur sequentially into a single simultaneous transmission window. By combining spatial multiplexing with the bandwidth request mechanism, multiple subscriber stations can send requests at the same time without requiring separate time slots or frequency resources, thus reducing overall overhead while maintaining allocation efficiency.
3Speed
If simultaneous bandwidth requests are submitted, then bandwidth allocation speed improves, but collision rate increases causing latency
Solution Approach 1:
The patent resolves the collision problem by adding spatial separation as an additional dimension. Instead of allowing simultaneous requests that collide in the same time-frequency resource, the system enables simultaneous requests from different spatial locations, with the base station using multiple antennas to separate them. This transforms collisions into separable spatial streams, maintaining high allocation speed while eliminating reliability issues.
4Productivity
If SDMA techniques are implemented, then collision rate decreases and throughput increases, but system complexity increases
Solution Approach 1:
The patent makes the base station's receive antennas serve multiple functions: they simultaneously receive bandwidth requests from multiple subscriber stations, separate these requests using spatial processing, and maintain backward compatibility with conventional transmission methods. This multi-functionality allows the system to achieve higher throughput through SDMA while managing complexity by reusing existing infrastructure for multiple purposes.
Data Source
AI summary
Embodiments of a base station and methods for allocating uplink bandwidth using SDMA are generally described herein. In some embodiments, uplink bandwidth request messages are received on a bandwidth request contention channel from one or more subscriber stations. The uplink bandwidth request messages are generated by the subscriber stations by modulating pilot subcarriers of a randomly selected disjoint pilot pattern with a randomly selected orthogonal sequence. The base station allocates uplink bandwidth to the subscriber stations when the uplink bandwidth request messages are successfully detected and decoded. The base station uses an SDMA technique to determine channel responses based on the orthogonal sequences to detect and decode the uplink bandwidth request messages.