Hidden node problem

However, the mechanism introduces latency, and the overhead can often be greater than the cost, particularly for short data packets.

Another example would be where A and C are either side of an obstacle that reflects or strongly absorbs radio waves, but nevertheless they can both still see the same AP.

IEEE 802.11 uses 802.11 RTS/CTS acknowledgment and handshake packets to partly overcome the hidden node problem.

As wireless LANs use the CSMA/CA protocol, nodes will wait their turn before communicating with the access point.

In the typical case of a WiFi network, increasing transmission power on the access point only will not solve the problem because typically the hidden nodes are the clients (e.g. laptops, mobile devices), not the access point itself, and the clients will still not be able to hear each other.

The alternative to forcing users to move is extending the wireless LAN to add proper coverage to the hidden area, perhaps using additional access points.

This eliminates the hidden node problem at the cost of increased latency and less maximum throughput.

With cellular networks the hidden node problem has practical solutions by time domain multiplexing for each given client for a mast, and using spatially diverse transmitters, so that each node is potentially served by any of three masts to greatly minimise issues with obstacles interfering with radio propagation.