Background
The hidden node problem occurs in the Manet and WLAN-infrastructure networks. If node A and Node B no longer transmit the power range of the other party, collision is triggered when a and B initiate communication with AP (or node C) at the same time. the more hidden nodes, the higher the probability of collision, and the lower the throughput.
Solution
- Increase the node transmission power and extend the transmission range
- Before starting data stream communication, introduce the RTS/CTS handshake mechanism to reserve the channel. Note that both RTS and CTS areBroadcast. RTS/CTS is generally used in WLAN-Infrastructure mode.
New problems caused by RTS/CTS:
- Overhead brought by the RTS and CTS packages.
- Exposed node problem, the sending node A cannot transmit data to the destination node B, because B cannot reply the CTS packet to a (node C exists outside the power range, and B is within the C power range, when C sends CTS to other nodes, it also informs B that channel is prohibited ). This phenomenon is more prominent in the MANET network.
- False blocking. For more information, see paper,Sobrinho, et. al. "Why RTS-CTS is not your ideal Wireless LAN Multiple Access Protocol", IEEE wcnc, 2005.
Optimization of RTS/CTS Use adaptive RTS threshold to replace the traditional fixed threshold. Refer to papers:
Ahsan, et. al. "exploiting packet distribution for tuning RTS threshold in IEEE 802.11," IEEE qbsc, 2010.
Choi, et. al. "A real-time updating algorithm of RTS-CTS threshold to enhance EDCA Mac performance in IEEE 802.11e wireless LANs," ieee vtc, 2004.
Chatzimisios, et. al. "optimisation of RTS/CTS handshake in IEEE 802.11 Wireless LANs for maximum performance," IEEE GlobeCom, 2004.
Summary The channel interference in wireless networks cannot be eliminated by 100%, but can be minimized as much as possible. Note that the reduction of collision does not mean that throughput must increase.
