Wireless Channel Management via Periodic NAV Reservation
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Solution Overview
Problem
In wireless communication systems using carrier sense multiple access with collision avoidance (CSMA/CA), the 'hidden node' problem occurs when a neighboring node within range of the receiving node but not the transmitting node transmits on the channel, causing the channel to appear idle, leading to failed data transmissions. Additionally, the frequent RTS/CTS handshake process for periodic data communications burdens channel and processing resources.
Innovation Solution
Incorporating an indication of the number of remaining data-ACK exchanges in the sequence within the data or ACK messages, along with the period and duration of each exchange, allowing neighboring nodes to set a periodic NAV and refrain from transmitting accordingly, thereby reducing the need for individual RTS/CTS handshakes for each exchange.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If RTS/CTS handshake process is performed for each periodic data communication, then reliability of data transmission is improved, but channel utilization deteriorates and processing burden increases
Solution Approach 1:
The patent merges multiple RTS/CTS handshake operations into a single handshake for a sequence of periodic data transmissions. The transmitting node performs one RTS/CTS exchange to reserve the channel for N periodic transmissions, eliminating the need for separate handshakes for each transmission. This combining approach maintains reliability by ensuring the channel is reserved for the entire sequence while improving productivity by reducing control overhead and channel access delays.
Solution Approach 2:
The patent applies preliminary action by performing the RTS/CTS handshake in advance for a sequence of N periodic transmissions rather than for each individual transmission. The initial handshake reserves the channel for the entire sequence, and subsequent periodic transmissions proceed without additional handshakes. This preliminary reservation reduces channel access delays and processing burden while maintaining transmission reliability.
2Reliability
If RTS/CTS handshake process is performed for each periodic data communication, then hidden node problem is mitigated, but device complexity increases
Solution Approach 1:
The patent combines multiple RTS/CTS handshake operations into a single handshake that covers a sequence of N periodic transmissions. This merging reduces device complexity by eliminating redundant handshake processing while maintaining hidden node problem mitigation through the initial channel reservation. The transmitting and receiving nodes only need to perform the handshake once per sequence rather than for each individual transmission.
Solution Approach 2:
The patent extracts the essential function of the RTS/CTS handshake (channel reservation and hidden node detection) and applies it once per sequence of transmissions rather than repeatedly for each transmission. By taking out the redundant handshake operations and replacing them with a single preliminary reservation, the system maintains reliability while reducing processing complexity.
3Reliability
If NAV period is set for each RTS/CTS message, then channel access control is improved, but loss of time increases due to frequent handshakes
Solution Approach 1:
The patent merges multiple NAV period settings into a single extended NAV reservation that covers a sequence of N periodic transmissions. Instead of setting NAV for each individual RTS/CTS exchange, the system sets one NAV period that reserves the channel for the entire sequence. This maintains channel access control by preventing other nodes from transmitting during the reserved period while eliminating the time overhead of repeated handshakes.
Solution Approach 2:
The patent enables continuous data transmission across N periodic intervals by establishing a single continuous channel reservation through the RTS/CTS handshake. The NAV period is set to cover the entire sequence of transmissions, allowing data to flow continuously without interruption from repeated handshake protocols. This eliminates idle time between handshakes and maintains continuous useful action.
Data Source
AI summary
Disclosed is a method and apparatus to help manage communication on a wireless channel when transmitting and receiving nodes will engage in a sequence of data-ACK exchanges with each other on the channel. As disclosed, the transmitting node and/or receiving node may include in at least one of the data-ACK exchanges an indication of how many data-ACK exchanges remain in the sequence and may further include indicia of how often each data-ACK exchange will occur and how long each data-ACK exchange will last. A neighboring node that is observing the channel to determine whether the channel is available may thus determine, based at least in part on the indication in the data-ACK exchange how many times to refrain from transmitting on the channel, how often to so refrain, and how long to refrain in each instance.