WLAN RTS CTS Subband Segmentation for Collision Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing wireless local area network (WLAN) systems face inefficiencies in medium access due to hidden and exposed node issues, leading to data frame collisions, particularly when determining appropriate channel bandwidths for transmissions between access points and stations.
Innovation Solution
A method and apparatus for transmitting frames in a WLAN that involves an access point transmitting a Request to Send (RTS) frame to multiple target stations through a channel, receiving a Clear to Send (CTS) frame from one station, and then transmitting downlink data through subbands within a data frame, with the RTS frame including identification information for each station to manage medium access effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the transmitting terminal transmits the RTS frame through a wide band channel (e.g., 160 MHz), then the channel bandwidth utilization is improved, but the destination terminal may not be able to respond through the same wide band if its current available bandwidth is limited (e.g., 80 MHz), leading to bandwidth mismatch and transmission inefficiency
Solution Approach 1:
The patent segments the wide band channel into multiple subbands (e.g., dividing 160 MHz into two 80 MHz subbands). The AP transmits the RTS frame through the wide band channel, and when the destination terminal responds with a narrower bandwidth (e.g., 80 MHz), the AP identifies which subband the response came from and transmits subsequent data frames through that specific subband. This segmentation allows the system to utilize wide band resources while adapting to the actual bandwidth capabilities of the destination terminal.
Solution Approach 2:
The patent implements dynamic bandwidth adaptation where the channel bandwidth is not fixed but adjusts based on the destination terminal's capabilities. The AP dynamically selects the appropriate subband for data transmission based on the CTS frame response, and can dynamically switch between different subbands for different data frames. This dynamic adjustment resolves the contradiction between utilizing wide band channels and adapting to limited terminal bandwidth.
2Area of stationary object
If the RTS frame is transmitted through a wide band channel, then the coverage area and reach are improved, but the likelihood of interframe collisions and data frame collisions increases due to hidden and exposed node issues
Solution Approach 1:
By segmenting the wide band channel into multiple subbands and using identification information in the CTS frame to identify which subband the response came from, the patent reduces the probability of collisions. Each subband can be treated as a separate transmission resource, and the AP can select specific subbands for data transmission based on the CTS response, thereby reducing the likelihood of interframe collisions compared to using the entire wide band channel.
Solution Approach 2:
The patent uses the CTS frame as an intermediary to establish a reliable transmission path before data transmission. The CTS frame contains identification information that acts as a mediator to match the RTS frame with the appropriate subband for subsequent data transmission. This intermediary mechanism ensures that data frames are transmitted only on subbands where the destination terminal has successfully received the RTS frame and is ready to receive data, reducing collisions from hidden and exposed node issues.
3Reliability
If the destination terminal responds with a CTS frame through a narrower bandwidth than the RTS frame was transmitted, then the transmission reliability for the response is improved, but the subsequent data frame transmission bandwidth is limited to the narrower bandwidth
Solution Approach 1:
The patent segments the wide band channel into multiple subbands, allowing the AP to transmit the RTS frame through the entire wide band channel (e.g., 160 MHz) while the destination terminal responds through its available bandwidth (e.g., one 80 MHz subband). The AP then uses the identification information in the CTS frame to identify which subband the response came from and transmits subsequent data frames through that identified subband. This allows the system to maintain wide band utilization for data transmission while ensuring reliable response transmission through the terminal's available bandwidth.
Data Source
AI summary
Disclosed are a method and apparatus for transmitting a frame. A method for transmitting a frame in a wireless LAN comprises the steps of: an AP transmitting a first RTS frame, through a primary channel, to a plurality of first target STAs; the AP receiving, from one target STA from among the plurality of first target STAs, a first CTS frame as a response to the first RTS frame, through the primary channel; and the AP transmitting, to the plurality of first target STAs, a plurality of pieces of first downlink data for each of the respective plurality of first target STAs, through a plurality of first subbands included in the primary channel on one first data frame, wherein a first RTS frame may include identification information for each of the plurality of first target STAs.