Voice Traffic Performance over Wireless LAN using the Point Coordination Function. Wei Wei Supervisor : Prof. Sven-Gustav Häggman Instructor: Researcher Michael Hall Helsinki University of Technology Communications Laboratory April, 2004. Contents. Background Objectives
Supervisor: Prof. Sven-Gustav Häggman
Instructor: Researcher Michael Hall
Helsinki University of Technology
- It brings increased efficiency and productivity.
- Fast and easy deployment.
- Can be set up where the wired networks are
imposible or difficult to reach.
- A backbone network that connects several access points or Basic Service Sets.
- Wired or wireless, implemented independently.
- In general, Ethernet is used as the backbone network technology.
- Connected to the DS, wireless-to-wired bridging function.
- In general, it’s referred to laptop computer.
- Frequency Hopping, Direct Sequence Spread Spectrum, Infra-red.
- It consists of a group of stations that are under control of DCF or PCF.
- It consists of several BSSs via DS.
- Provides larger network coverage area.
- A set of 802.11 wireless stations communicate directly with each other, without using access point.
- Also called Independent Basic Service Set (IBSS).
- The network consists of at least one access point and a set of mobile stations.
- AP bridges the wireless traffic to a wired Ethernet or the Internet.
- AP can be compared with a base station used in a celluar network.
Taken from IEEE 802.11 standard
- After a SIFS, only polled MS can send
- After a PIFS, only AP can send (PCF control)
- After a DIFS, every station can send according
to CSMA/CA (DCF)
- Realistic traffic model
- unpredictable Beacon frame delay resulting in shortened CFP
- unknown transmission time of polled stations making it difficult for PC to predict and control the polling scheldule for the remainder of CFP
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