IEEE 802.11ad WLAN için yöneltilmiş MAC protokolü

Millimeter-wave (mmWave) communications is a promising technology that enables high rate (Giga-bit) multimedia applications. We consider the directional multigigabit (DMG) transmission problem in IEEE 802.11ad wireless local area network (WLAN). Traditional directional MAC uses Network Allocation Vector (NAV) to decrease collisions drastically by making nodes which have their NAV set, defer their communication. Directional MAC protocols usually implement either directional RTS/CTS (DRTS/DCTS), multi-directional sequential (Circular) RTS/CTS (CRTS/CCTS) or multi-directional concurrent RTS/CTS control packets. IEEE 802.11ad MAC implements an A-BFT phase where each node beamforms (BF) with the Access Point (AP). In this thesis, we propose a Directional MAC protocol for Basic STAs (DMBS) that uses DRTS/DCTS as well as CRTS/CCTS control packets along with two NAVs (NAV1 and NAV2) to fully leverage spatial reusability and tackle deafness and hidden terminal problem without using any complicated hardware. DMBS makes each node keep a beamforming table (BF table) to store location information of other nodes. We implement an Intelligent Listening during A-BFT (ILA) mechanism where STAs gather beamforming information by listening to the channel during A-BFT phase and update their BF table. This considerably reduces the overall network beamforming associated overhead. Furthermore, if a node already have BF information of the destination node, it uses DRTS/DCTS packet to communicate otherwise CRTS/CCTS packet is used to gather location information. This assures that the control overhead is minimal and the protocol doesn't have to use any complicated technique or hardware or rely on upper layers for location tracking. NAV1 keeps a list of all the nodes that are busy and is set every time a RTS/CTS packet is received. A node would not initiate communication with a node that is in NAV1 subsequently reducing deafness. With the help of RTS/CTS control packets received, the nodes determine whether they can cause interference to an ongoing communication. NAV2 is only set if a node can cause interference to an ongoing communication. If NAV2 is set, then the node defers its multi-directional communication but still communicates directionally. This increases spatial reusability all the while keeping interference minimal which increases the overall network throughput. We perform extensive simulations by comparing DMBS with other commonly used protocols and by comparing different features of DMBS in different scenarios. Simulations demonstrate that the DMBS improves the network throughput considerably, especially at higher network size.