Download presentation
Presentation is loading. Please wait.
Published byLewis Rodgers Modified over 8 years ago
1
Ben-Gurion University of the Negev Department of Communication Systems Engineering
3
Great customer demand for wireless communication. Momentum of the wireless market. Customers demand for wireless communication anytime, anywhere. Wireless necessity
4
WiMAX WiMAX - known as IEEE 802.16, refers to a wireless digital communication system. WiFi WiFi - known as IEEE 802.11, uses high frequency radio signals to send and receive data over short distances. WiMAXWiFi Supports handoff - mobility Managed 1.5 km in urban area Metropolitan area network (MAN) Does not support handoff ~100 m coverage area Local area network (LAN)
6
Neither Technology Makes Possible The Best Available Network at All Times. In Areas That WiFi Has Already Proven Itself as a Good Solution WiMAX May Not Be Able to Compete. Latency Bandwidth Mobility Cost
7
WiMAX Base Station WiFi Access Point Handoff among heterogeneous wireless access network technologies.
8
Time In WiFi Battery WiMAX Resources Signal Strength WiMAX WiFiWiFi The Decision Function returns the protocol to which the host should connect to:
10
Last two years - WiFi technology and Decision Function were implemented. focusing- implementing the WiMAX technology This year focusing- implementing the WiMAX technology.
12
Admission Control - Determines if a new call request is granted, or rejected. Scheduler - Allocates bandwidth according to BW request from MSs. MAC layer PHY layer OFDMA technology allows using several sub-channels simultaneously with high spectral efficiency. Synchronized frames between the base station and the hosts.
13
VoiceVoice VideoVideo DataData BW Request Per Application Type: BW Request Per Application Type: - Not Required - Current Queue size Mobile Station BW-Request
14
BW-Response MS WiMAX Base Station MS PriorityQoSBandwidth…PriorityQoSBandwidth…
15
frequency-timeunit The minimum frequency-time resource unit is one slot. Modulation TypeCoding Rate The host Modulation Type and Coding Rate will determine the number of bits in one slot. Coding Rate ½ 3/4 Modulation Type QPSK QAM 16 QAM 64
16
highest to lowest priority. Bandwidth allocation Per Frame from highest to lowest priority. Applications & Priority VOICE: Real time traffic Constant bit–rate VOICE: Real time traffic Constant bit–rate VOICE: Real time traffic Constant bit–rateVOICE: Real time traffic Constant bit–rate VIDEO: Real time traffic variable bit–rate VIDEO: Real time traffic variable bit–rate DATA: Non real time traffic variable bit–rate DATA: Non real time traffic variable bit–rate VIDEO: Real time traffic variable bit–rateVIDEO: Real time traffic variable bit–rate DATA: Non real time traffic variable bit–rateDATA: Non real time traffic variable bit–rate
17
Applications & QoS Requirements QoS requirements. Bandwidth Allocation algorithm with respect to QoS requirements. VoiceVoice VideoVideo DataData - Fixed numbers of time slots - Maximum latency tolerance - Best effort, no QoS guarantee
18
slot allocation BW Response to specific host includes amount of slot allocation for next frame. Synchronized DownLink/UpLink transmissions. Downlink Subframe TTG OFDMA Symbol Number Subcarrier Number DL Map DL Burst #3DL Burst #4 DL Burst #1 DL Burst #5 DL Burst #2 Ranging Subchannel Preamble UL Burst #1 UL Burst #2 UL Burst #3 UL Burst #4 UL Burst #5 Uplink Subframe FCH UL Map Slot One Subchannel 1->6 OFDMA Symbols Slot …… … … …
19
new connection established Admission control decides whether a new connection can be established. A connection is admitted if: enough bandwidth 1.There is enough bandwidth to accommodate the new connection. receive QoS guarantees 2.The newly admitted connection will receive QoS guarantees in terms of both bandwidth and delay. existing connections maintained 3.QoS of existing connections is maintained.
21
Combined WiFi & WiMAX device 16 km 2 Area 4 Fixed base stations (802.16) 24 Fixed access points (802.11) Three service types – Data, Video and Voice 300 Hosts Two Host Types: 2/3 Pedestrian (0-3 km/h) 1/3 Cars (50-80 km/h)
22
Host served by WiMAX Host in IDLE state Host served by WiFi Host denied service
23
6 Simulation Types: 1. WiMAX only 2. WiMAX + WiFi No DF (If WiFi exists connect to it) 3. WiMAX + WiFi DF #1 (Signal Strength) 4. WiMAX + WiFi DF #2 (Number of Slots) 5. WiMAX + WiFi DF #3 (Battery) 6. WiMAX + WiFi DF #4 (Time in WiFi Zone) 10 runs per type (different seeds)
Similar presentations
© 2025 SlidePlayer.com. Inc.
All rights reserved.