UWB Superframe MAC Protocol for Power Reduction
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Solution Overview
Problem
The conventional CSMA/CA method for ultra wideband impulse communication systems in sensor networks and low-rate WPANs faces issues with high power consumption, complex device management, and increased collision probability due to the need for continuous channel monitoring and complicated time hopping patterns, especially when dealing with multiple devices and wide frequency bands.
Innovation Solution
A radio communication system that operates on a superframe basis, with a network coordinator managing devices into groups and allocating time slots, allowing for contention-free periods and reducing power consumption by activating devices only during active periods and inactivating them during inactive periods, using a pre-arbitrated slot allocation-based MAC protocol and binary exponential backoff method.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If CSMA/CA method is used for multiple access in UWB impulse communication system, then channel access control is achieved, but power consumption increases due to continuous channel monitoring
Solution Approach 1:
The patent implements periodic channel monitoring instead of continuous monitoring by defining specific superframe structures with active and inactive periods. Devices monitor channels only during designated active periods and enter low-power states during inactive periods, reducing power consumption while maintaining reliable channel access control through periodic CSMA/CA operations.
2Reliability
If devices remain in active state to monitor channel, then channel access is controlled, but power consumption increases
Solution Approach 1:
The patent introduces dynamic power state management where devices transition between active and inactive states based on their role in the superframe structure. Coordinators remain active during beacon periods and contention access periods, while other devices dynamically switch to inactive states during these periods, activating only during contention-free periods or when data needs to be transmitted, thus reducing overall power consumption while maintaining channel access control.
3Reliability
If hierarchical backoff method is used, then collision between devices is reduced, but device complexity increases
Solution Approach 1:
The patent segments the backoff mechanism into hierarchical levels: superframe-level backoff and time-slot-level backoff. This segmentation allows devices to apply different backoff strategies at different granularity levels, reducing collisions through multi-level randomization while keeping individual backoff logic relatively simple and modular, thus managing device complexity effectively.
4Productivity
If multi-piconets operate with different frequency bands, then network capacity increases, but transmitting and receiving structure complexity increases
Solution Approach 1:
The patent implements a universal time-hopping spread spectrum mechanism that operates across multiple frequency bands (3.1-10.6 GHz divided into 500 MHz bands). The same time-hopping code and synchronization approach are applied universally across all frequency bands and piconets, allowing devices to handle multiple bands with a single unified receiving structure, thus increasing network capacity while minimizing device complexity.
5Adaptability or versatility
If arbitrary time hopping pattern is used, then UWB impulse signal is applied to time hopping system, but time hopping pattern management becomes complicated with many devices
Solution Approach 1:
The patent enforces homogeneous time-hopping pattern management across all devices in the network. All devices use the same time-hopping code length, same synchronization reference (coordinator's beacon), and same pattern generation algorithm. This homogeneity simplifies management significantly, as the coordinator can manage a single set of time-hopping parameters for the entire network rather than individually managing arbitrary patterns for each device, while still maintaining the flexibility of time-hopping spread spectrum.
Data Source
AI summary
Provided is a radio communication system for ultra wideband (UWB) impulse communications and a radio communication apparatus and method thereof. The present patent provides a radio communication system that can minimize power consumption by eliminating a need for carrier detection and sharing transmission/reception time information in UWB impulse communications. The system includes a network coordinator; and one or more devices communicating on a superframe basis in subordination to the network coordinator. The devices perform data transmission/reception in predetermined time slots and then they are inactivated to thereby reduce power consumption.