SDMA Virtual Sub-Sector Beamforming for Spectral Efficiency
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Solution Overview
Problem
Current wireless communication systems face limitations in spectral efficiency due to high map overheads and interference in SDMA networks, particularly in the transmission of control channels and the inability to beamform maps, which restricts peak throughput and spectral efficiency gains.
Innovation Solution
The method involves dynamically allocating transmission resources on a frame-by-frame basis by dividing sectors into virtual sub-sectors, selecting pairs of subscriber devices with minimal interference, generating orthogonal time-frequency allocation maps, and beamforming transmissions to these sub-sectors, allowing for efficient reuse of resources and reduced interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of sectors per site is increased to increase spectral efficiency, then spectral efficiency may improve in theory, but peak rate and peak throughput decrease due to increased interference from other sectors
Solution Approach 1:
The invention divides a single sector into multiple virtual sub-sectors (e.g., 2-4 sub-sectors per physical sector). Each virtual sub-sector is assigned a unique beamforming signature, allowing simultaneous transmissions to different spatial directions within the same physical sector. This segmentation enables multiple users to share the same time-frequency resources with reduced interference, thereby increasing spectral efficiency without adding more physical sectors that would cause inter-sector interference.
2Productivity
If SDMA is implemented to increase spectral efficiency and reduce delay, then throughput increases, but map overhead increases and devices become more complex
Solution Approach 1:
The invention merges multiple sector-specific maps into a single unified map that covers all virtual sub-sectors within a physical sector. This unified map contains time-frequency resource allocations for all sub-sectors, allowing subscriber devices to receive comprehensive scheduling information in one message rather than multiple separate maps. This reduces control channel overhead and simplifies device processing while maintaining SDMA capabilities.
3Power
If beamforming is used to increase received power for subscriber devices, then signal quality improves, but the additional power increase yields limited improvement in throughput due to multi-user scheduling constraints
Solution Approach 1:
The invention dynamically assigns different beamforming signatures to different virtual sub-sectors based on real-time channel conditions and traffic demands. The base station adaptively adjusts beamforming weights and signatures for each sub-sector, allowing optimal spatial resource allocation. This dynamic approach enables the system to exploit spatial diversity and multiplexing gains, significantly improving throughput beyond what static beamforming can achieve in multi-user scenarios.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances spectral efficiency without increasing sector costs, supports operation with devices unaware of SDMA, and achieves higher throughput by optimizing resource allocation and interference reduction.
Implementation Method 1
a beam from the base station is directed towards that subscriber device (referred to herein as 'beamforming'), and the received power for that subscriber device is respectively increased
Implementation Method 2
In a Spatial Division Multiplexing Access ('SDMA') type of radio network, where a number of channels are transmitted simultaneously to a number of users
Data Source
AI summary
In a wireless network employing Spatial Division Multiplexing Access (“SDMA”) in at least one of its cells, a method is provided for dynamically allocating transmission resources to different subscriber devices. The method comprises the steps of: providing at least one base station comprising at least one antenna array; providing one or more sectors associated with that wireless communications network; dynamically dividing one or more of the sectors into a plurality of virtual sub-sectors, each allowing communications between the base station and at least one respective subscriber; from among the plurality of the virtual sub-sectors, selecting at least one pair of subscriber devices wherein each of the pair of subscriber devices is not interfered substantially by transmissions directed to the other subscriber of that pair; for each of the divided sectors, generating plurality of time frequency allocation maps; transmitting the generated maps to all virtual sub-sectors associated with the respective sector; and for each of the sectors, beamforming the transmissions to be conveyed to the subscriber devices' pairs, summing them and conveying the summed result towards the array antenna.