In a WiFi network, assume a WiFi station does not silence itself for an RTS/CTS reception from other stations and it keeps on transmitting. I have few questions related to this scenario,

1.Will that affect the whole network?

2.How this kind of an issue is handled?

3.CSMA/CA is applicable only for the connected stations or all WiFi stations in the vicinty of the stations and APs?


2 Answers 2


Will that affect the whole network?

All stations that now lose packets are affected. I.e. every station at which your malfunctioning's station is strong enough to damage received packets.

How this kind of an issue is handled?

Well, since that bad station won't always have something to send, it will probably not be handled at all: packets that collided will simply be re-sent, which the user only notices through increased latency and reduced throughput.

If that bad station continuously transmits, the its WiFi channel is simply blocked, which means the other stations notice that none of what they send ever gets acknowledged, and they'll leave that network eventually. An access point might use that knowledge and change channels, but that would assume it's configured to do that.

CSMA/CA is applicable only for the connected stations or all WiFi stations in the vicinty of the stations and APs?

Think about this logically: if you only forced connected stations to adhere to the rules of cooperation, everyone would suffer when a new station enters an area.

So, it doesn't only apply to connected stations. It also applies to unconnected stations. And even non-WiFi devices: in many countries (most) any ISM-band device with a maximum duty cycle above 1‰ typically needs to do "listen before talk".


Appearance of RTS/CTS signaling presumes the CSMA/CA implementation is supplemented in your application with Multiple Access Collision Avoidance, a technique used to fight hidden/exposed terminal problems. It is unclear if you ask about scenarios which the technique is designed for, or you have concerns about a station violating the CSMA/CA + MACA protocol timing conventions. Any way,

(my best effort to answer item 1 of your question): the disturbance by a station, this disturbance being either "legal" and described in protocol, or the station is malfunctioning/malicious, affects only the nodes that receive the undesired transmittance, and not the whole network.

(my best effort to answer item 2): If this transmittance can be interpreted as regular in the framework of protocol rules, the affected nodes that request the access to the occupied channel enter the exponential backoff. Otherwise, the node considers this corrupted transmission as an external interference and avoids the busy channel for the period when the node senses this interference.

As for item 3: if my treatment of the first two items does not resolve your confusion, please clarify your question in terms of CSMA/CA + MACA scenarios and protocol signaling timelines.

You can read about some aspects of control and data frame exchanges at the 802.11ah physical level and see the timeline diagrams in the article Reliability and scalability evaluation with TCP/IP of IEEE802.11ah networks. I intentionally refer you to the article covering application specific features of IEEE802.11 signaling. Although you find wireless protocol descriptions in IEEE standards and detailed explanations elsewhere, with the ns-3 simulator, which is a workhorse of network protocol development similar to as SPICE is a must-have tool for circuit designers, you can simulate and examine scenarios like that of your question -- whether your are interested in details of signal timing or what happens in the presence of malfunctioning devices. You should have a certain experience with computer programming languages, though. NS-3 uses C/C++ and Python for module development and as languages of simulation scripts.


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