Wireless Station Concurrent Transmission via CIR Evaluation
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Solution Overview
Problem
Conventional wireless communication systems face limitations in transmission capacity due to the 'exposed-node problem' and spatial density of wireless stations, where interference signals lead to prohibited transmissions even if they do not obstruct the desired signal, and existing solutions require centralized control or specific positional relations for concurrent transmission.
Innovation Solution
A wireless communication apparatus with a demodulation unit, link information management unit, and concurrent transmission link management unit that autonomously judges and controls transmission timing to allow concurrent links without centralized control, using received-signal strength and carrier-to-interference ratio (CIR) to determine interference and enable simultaneous data transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If CSMA method is used for access control, then carrier sense function detects interference signals, but transmission is canceled even when interference is too weak to obstruct communication (exposed-node problem)
Solution Approach 1:
The patent introduces the concept of interference area and non-interference area with different communication rules. Wireless stations in interference areas must wait for the interference signal to finish, while stations in non-interference areas can transmit simultaneously. This local differentiation resolves the exposed-node problem by allowing transmissions that would otherwise be canceled due to weak but detectable interference signals.
Solution Approach 2:
The patent dynamically determines transmission permission based on the carrier-to-interference ratio (CIR) threshold. The access control mechanism changes from a static prohibition (any detected interference stops transmission) to a dynamic decision process that compares signal strength ratios, allowing flexible adaptation to varying interference conditions and improving overall transmission capacity.
2Productivity
If centralized control is used to manage concurrent transmission, then transmission capacity improves, but device complexity increases
Solution Approach 1:
The patent enables wireless stations to autonomously determine whether they can transmit concurrently by measuring the carrier-to-interference ratio themselves. Each station independently evaluates the interference condition and makes its own transmission decision without requiring centralized control or coordination messages from other stations, thereby reducing system complexity while maintaining high transmission capacity.
3Reliability
If transmission is prohibited when any interference signal is detected, then packet collisions are avoided, but space-use efficiency decreases due to exposed-node problem
Solution Approach 1:
The patent divides the communication environment into interference areas and non-interference areas with different transmission rules. Stations in non-interference areas can transmit simultaneously with stations in interference areas, increasing space utilization. This local differentiation maintains collision avoidance where needed while enabling efficient concurrent transmission where safe.
Solution Approach 2:
The patent changes the access control parameter from a binary state (transmit or prohibit) to a continuous evaluation based on carrier-to-interference ratio. By using CIR threshold comparison, the system can fine-tune transmission permissions and optimize space utilization while maintaining reliable communication.
Data Source
AI summary
When communicating with a second wireless station, a first wireless station judges, based on link-related information received from the second wireless station and link-related information extracted from a signal transmitted by a fourth wireless station, whether a transmission link from the third wireless station to the fourth wireless station and a transmission link from the first wireless station to the second wireless station can be concurrently established without interference with each other. If judging affirmatively, the first wireless station transmits a signal to the second wireless station in synchronization with a signal transmitted by the third wireless station to the fourth wireless station.