Presentation on theme: "Lesson 10: WiFi and WiMAX MAC Analysis Giovanni Giambene Queuing Theory and Telecommunications: Networks and Applications 2nd edition, Springer All rights."— Presentation transcript:
The Classical IEEE 802.11 Wireless System zThe classical IEEE 802.11 system (1997) is characterized by a channel bit-rate of 1 or 2 Mbit/s in the ISM frequency band at 2.4- 2.4835 GHz with two different wireless transmission techniques: yDirect Sequence Spread Spectrum (DSSS), yFrequency Hopping Spread Spectrum (FHSS). zThese spread spectrum techniques are used to reduce the interference produced by other instruments that use ISM frequencies (e.g., microwave ovens, cordless phones, Bluetooth and other appliances). zThere is also the possibility of infrared transmissions with a wavelength in the range from 850 and 950 nm.
QoS Support in WiMAX zThe WiMAX standard envisages the following traffic classes with related resource allocation methods: yUGS (Unsolicited Grant Services): it supports constant bit-rate services (CBR) with specified max sustained rate, max latency tolerance, and jitter tolerance. yrtPS (real-time Polling Services): it is used for real-time services such as streaming video and VoIP with activity detection. This offers a variable bit-rate, but with a guaranteed minimum rate and guaranteed delay. yertPS (enhanced Real-Time Variable Rate), specified in 802.16e, is used for VoIP services with variable packet sizes as opposed to fixed packet sizes; typically, silence suppression is used. ynrtPS (non-real-time Polling Service): supports non-real-time variable size data packets, e.g., FTP. yBE (Best Effort services).