Wireless Multihop Relay Scheduling Using Spatial Grouping
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Solution Overview
Problem
Current wireless multi-hop relay communication systems face inefficiencies in transmission scheduling, leading to suboptimal link quality and system capacity, especially for users at cell boundaries, due to increased interference and hardware costs associated with directional antennas.
Innovation Solution
The method involves equipping base stations and relay stations with directional or sector antennas, allowing them to measure and group based on interference levels, enabling efficient reuse of radio resources through time division duplex access and permutation of service orders across cells to minimize interference and maximize spectrum efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If relay stations are deployed to improve link quality for users at cell boundaries, then coverage area and link quality are improved, but system complexity and hardware costs increase
Solution Approach 1:
The system segments relay stations into different groups based on their service areas and interference characteristics. Each group is scheduled independently, allowing manageable complexity while maintaining improved link quality through targeted relay deployment.
Solution Approach 2:
The scheduling mechanism dynamically adjusts the service order of different relay station groups based on current system conditions and interference levels, enabling adaptive optimization without requiring complex static configuration.
2Productivity
If multiple serving stations are active simultaneously to improve spectrum efficiency, then spectrum efficiency is improved, but interference level increases
Solution Approach 1:
The system employs periodic time-division scheduling where different groups of serving stations are activated in alternating time slots. This periodic activation allows multiple stations to be utilized over time while controlling instantaneous interference levels through structured time separation.
Solution Approach 2:
The scheduling mechanism changes the temporal parameters of station activation, switching which groups are active at different time slots. This parameter adjustment enables the system to achieve high overall spectrum efficiency while maintaining acceptable interference levels at any given moment.
3Reliability
If transmission power of base station is increased to improve link quality, then link quality is improved, but transmission cost and interference level increase
Solution Approach 1:
Instead of uniformly increasing base station transmission power across all directions, the system applies power control locally to specific relay station groups based on their channel conditions and service requirements. This localized approach improves link quality where needed while minimizing overall energy consumption and interference.
4Reliability
If relay stations are disposed outside coverage area with directional antennas to improve link quality, then link quality is improved, but hardware cost increases
Solution Approach 1:
The system designs relay stations with universal omni-directional antennas that can serve multiple functions and directions, eliminating the need for expensive directional antennas while maintaining the ability to provide targeted service to users at cell boundaries through intelligent scheduling.
Data Source
AI summary
A scheduling technique for wireless multihop relay communication systems is provided. With spatial separation caused by the shadowing effect of surrounding buildings, a base station and its relay stations in a single cell are divided into several groups by following the rule that stations with severe potential interference are separated into different groups. The base station arranges the scheduling of these groups and serves these groups sequentially in the time domain. To take advantage of shadow effect, the same radio resources can be scheduled for relay stations within the same group due to the isolation of interfering signals. In the present invention, base stations and relay stations are equipped with directional antennas or sector antennas to further exploit the advantage of spatial separations. Different relay groups can also reuse the radio resource through appropriate power control. The cell capacity can be enhanced substantially because of aggressive radio resource reuse.