FDD WLAN Trigger Frame for Simultaneous Uplink Downlink
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Solution Overview
Problem
Current wireless local area network (WLAN) systems face challenges in improving spectrum efficiency and area throughput, especially in dense environments with multiple access points and stations, and in outdoor settings, where existing technologies suffer from low-latency communication and channel contention issues.
Innovation Solution
The implementation of a frequency division duplex (FDD) method in WLAN systems, where a trigger frame is used to facilitate simultaneous transmission and reception of physical layer protocol data units (PPDUs) across primary and secondary channels, allowing for fast uplink transmission without channel contention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If frequency division duplex (FDD) method is implemented to enable simultaneous transmission and reception across primary and secondary channels, then spectrum efficiency and area throughput are improved, but device complexity and protocol overhead increase due to trigger frame coordination requirements
Solution Approach 1:
The patent divides the communication channel into primary and secondary channels, allowing simultaneous uplink and downlink transmissions on different frequency segments. The trigger frame mechanism segments the coordination process into specific fields ( bandwidth information, resource allocation) to manage complexity while enabling FDD operation
Solution Approach 2:
The patent transitions from time-division duplex (TDD) to frequency-division duplex (FDD) by adding a frequency dimension to the communication protocol. This allows simultaneous transmissions in different frequency domains while using trigger frames to coordinate resource allocation across these dimensions
2Loss of time
If trigger frame mechanism is used to coordinate simultaneous uplink and downlink transmissions, then low-latency communication is achieved, but message overhead and processing complexity increase
Solution Approach 1:
The trigger frame is transmitted in advance to allocate resources for upcoming uplink and downlink transmissions. By preliminarily specifying bandwidth information, resource units, and transmission parameters in the trigger frame, the system enables immediate simultaneous transmissions without waiting for channel contention or arbitration
Solution Approach 2:
The trigger frame acts as an intermediary message that coordinates between the access point and stations, carrying bandwidth information and resource allocation details that enable simultaneous transmissions without direct negotiation or contention between transmitting devices
3Productivity
If simultaneous downlink and uplink transmissions are enabled through FDD, then area throughput increases, but interference management and signal separation become more difficult
Solution Approach 1:
The patent segments the frequency spectrum into primary and secondary channels with distinct resource units allocated to specific directions (uplink or downlink). This segmentation prevents frequency collision and simplifies signal separation at the receiver by knowing which frequency resources correspond to which transmission direction
Solution Approach 2:
Different resource units within the frequency spectrum are assigned different local qualities or purposes - some are designated for uplink, others for downlink. The trigger frame specifies which resource units have which characteristics, enabling receivers to properly separate and process signals based on their allocated frequency resources
Data Source
AI summary
A method and a device for transmitting and receiving a PPDU on the basis of an FDD in a wireless LAN system are presented. Particularly, an AP transmits a trigger frame to a first STA and a second STA. The AP transmits a first downlink (DL) PPDU to the first STA on the basis of the trigger frame. The AP transmits a second DL PPDU to the second STA on the basis of the trigger frame. The AP receives a first uplink (UL) PPDU from the second STA on the basis of the trigger frame. The trigger frame includes bandwidth information of a primary channel and a secondary channel. The first DL PPDU is transmitted through the primary channel. The second DL PPDU and the first UL PPDU are transmitted through the secondary channel. The first and second DL PPDU are simultaneously transmitted. The first UL PPDU is received after a preset period after the second DL PPDU is transmitted.