Adaptive Array Antenna Space Division Multiplexing
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Solution Overview
Problem
The existing wireless LAN systems, particularly those following the IEEE 802.11 standard, face challenges in combining carrier sense methods with adaptive array antennas, leading to difficulties in coexistence and insufficient communication capacity, especially when handling multiple data streams.
Innovation Solution
A communication system and method that introduce new frame formats for the RTS, CTS, and ACK signals to enable space division multiplexing, allowing an access point with an adaptive array antenna to transmit data to multiple stations simultaneously while coexisting with stations operating under conventional protocols, by learning weightings for the adaptive array antenna based on clear to send signals and response signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If carrier sense method is used for media access control, then collision avoidance is achieved, but communication capacity is insufficient for multiple data streams
Solution Approach 1:
The patent segments the communication channel into multiple spatial streams by introducing adaptive array antenna technology. Instead of using a single carrier sense method for one data stream, the system divides the wireless medium into multiple independent spatial channels, each capable of carrying separate data streams simultaneously. This segmentation resolves the contradiction by maintaining collision avoidance through carrier sense while increasing communication capacity through spatial multiplexing.
Solution Approach 2:
The patent transitions from two-dimensional time-frequency domain communication (single carrier sense) to three-dimensional space-time-frequency domain communication by introducing the spatial dimension through adaptive array antennas. This dimensional expansion allows multiple data streams to coexist in different spatial directions while maintaining collision avoidance protocols, thereby resolving the capacity limitation of traditional carrier sense methods.
2Productivity
If adaptive array antenna is introduced to increase communication capacity, then multiple data streams can be transmitted, but coexistence with conventional stations becomes difficult
Solution Approach 1:
The patent implements universality by designing the adaptive array antenna system to perform multiple functions: it can operate in high-capacity mode with multiple data streams when advanced stations are present, and automatically degrade to conventional single-stream mode when only legacy stations are detected. This multi-functionality ensures compatibility with conventional IEEE 802.11 stations while enabling enhanced capacity when needed, resolving the coexistence contradiction.
Solution Approach 2:
The system dynamically adjusts its operation mode based on the presence and capabilities of surrounding stations. The access point continuously monitors the network environment and adapts its transmission strategy - switching between spatial multiplexing mode and conventional mode as conditions change. This dynamic adaptability allows the system to maintain high capacity when possible while ensuring seamless coexistence with conventional stations, resolving the contradiction between enhanced capacity and adaptability.
3Productivity
If new frame formats are introduced for space division multiplexing, then communication capacity increases, but device complexity increases
Solution Approach 1:
The patent extracts the complex spatial multiplexing functionality into a dedicated control mechanism separate from the core data transmission protocol. The new frame formats introduce minimal additional signaling elements that carry only the essential spatial stream information, while the bulk of the data transmission continues to use standard formats. This extraction approach increases capacity through space division multiplexing while limiting the complexity increase to only the necessary control overhead.
Data Source
AI summary
A communication system for carrying out data communication among a plurality of communication stations is disclosed in which a first communication station for transmitting to other communication stations a Request To Send (RTS) signal for requesting a transmission upon the start of the data transmission; and a plurality of second communication stations transmitting to other communication stations a Clear To Send (CTS) signal for notifying the completion of preparing the reception, wherein the first communication station transmits the RTS signal describing at least each of addresses the second communication stations that are desired to receive the data, and receives a plurality of CTS signals transmitted from each of the second communication stations in order to increase communication capacity.