S15. How is the hidden terminal problem solved? Flashcards
What is the hidden terminal problem?
The hidden terminal problem occurs in wireless networking when a station (terminal) is unable to detect other stations that are within range of the access point (AP) but are hidden from it due to obstacles or distance.
What are the effects of the hidden terminal problem?
Hidden terminals can lead to collisions and degraded network performance when multiple stations, unaware of each other’s presence, transmit simultaneously to the AP.
What techniques are used to address the hidden terminal problem?
CSMA/CA, RTS/CTS, Virtual Carrier Sensing, adjusting the transmission power of stations
What is CSMA/CA and how does it address the hidden terminal problem?
CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance) is a protocol used in wireless networks to avoid collisions by listening to the wireless medium before transmitting data. Stations must wait for the medium to be idle before transmitting, reducing the risk of collisions.
What is RTS/CTS and how does it address the hidden terminal problem?
Request-to-Send/Clear-toSend (RTS/CTS) is a mechanism used in IEEE 802.11 wireless networks in combination with CSMA/CA in scenarios where hidden terminals may occur. When a station wants to transmit data, it first checks if the channel is idle, then initiates an RTS/CTS exchange. This involves the sender station transmitting an RTS frame to the AP or other station to which it wants to send data. The RTS frame includes the duration of time the sender intends to use the channel for its transmission. Upon receiving the RTS frame, the recipient responds with a CTS frame, granting the sender permission to transmit. The sender can then proceed to transmit its data within the specified duration.
What is virtual carrier sensing and how does it address the hidden terminal problem?
Virtual Carrier Sensing is a technique implemented in some protocols that involves stations exchanging information about neighboring stations and their transmission status. This allows stations to make more informed decisions about when to transmit, even if they cannot directly sense the activity of hidden terminals.
How does adjusting the transmission power of stations address the hidden terminal problem?
Adjusting the transmission power of stations can help mitigate the effects of hidden terminals. By reducing transmission power, stations limit their coverage area, reducing the likelihood of hidden terminals interfering with each other.
