Chapter 8: WMAN - IEEE / WiMax. Introduction and Overview

Transcription

1 Chapter 8: WMAN - IEEE / WiMax Introduction and Overview

2 IEEE and WiMAX IEEE Working Group on Broadband Wireless Access, established 1999 Worldwide Interoperability for Microwave Access Objective: Standardisation of Wireless Metropolitan Area Network (WMAN) WiMAX: industry consortium provides standardised PHY and MAC Interoperability between devices Compatibility to higher protocol layers Network architecture First standard published in

3 IEEE evolution (1) a e Date Completed December 2001 January 2003 June 2004 December 2005 Spectrum GHz < 11 GHz < 11 GHz < 6 GHz Operation LOS, only SC Non-LOS OFDM Non-LOS OFDMA NLOS and Mobile Bit Rate Mbps Up to 75 Mbps Up to 75 Mbps Up to 15 Mbps Cell Radius 2-4 km 5-8 km 5-8 km 2-4 km Hussain, APRICOT

4 IEEE evolution (2) Air Interface for Fixed and Mobile Broadband Wireless Access System PHY and MAC Layers for Combined Fixed and Mobile Operation in Licensed Bands (former e) Network Management (NetMan): Management Information Base (MIB), Management Plane Procedures and Services Coexistence in license-exempt bands

5 Further developments IEEE h: Improved coexistence mechanisms in licenseexempt operation (2010) IEEE j: Multihop Relay (2009) PMP compliant, multihop operation for OFDMA PHY IEEE m: Advanced Air Interface with data rates of 100 Mbit/s mobile and 1 Gbit/s fixed (2011) Also known as Mobile WiMAX Release 2 or WirelessMAN- Advanced Aiming at fulfilling the ITU-R IMT-Advanced requirements on 4G systems IEEE p: Enhancements to Support Machine-to- Machine Applications (2012) IEEE IEEE evolution (3) IEEE n: Reliable Operation (2013)

6 Fundamentally different MAC layer approaches: : distributed control, contention based access : centrally coordinated, frame based Similar OFDM based PHY modes Quality of service (QoS) support vs Guaranteed multimedia QoS in In the first years, no QoS support in standard Higher data rates due to reduced MAC overhead Much longer distances due to allocated frequency band and higher transmit power

7 WiMax deployment: point-to-point backbone (LOS) 7

8 WiMAX deployment: backhaul links point-to-multipoint, non-line-of-sight, stationary 8

9 WiMAX deployment: user access point-to-multipoint, non line-of-sight, mobile 9

10 WiMAX Protocol Stack Handling higher layer protocols Channel access, connection handling, QoS Authentication, secure key exchange, encryption 10

11 profiles and performance comparison 11

12 MAC layer For data transport, base station controls channel variable-length time slot in a superframe is assigned by base station to each mobile station Encapsulation of different (wired) packet formats on the air interface: Ethernet, ATM, raw IP Connection-oriented: station needs to register in order to get a time slot allocated Because of time slots, QoS provisioning easy Connection setup by random access DES/AES encryption 12

13 QoS classes Unsolicited Grant Service (UGS) Periodic fixed-size packets, e.g. T1 transport Extended Real-Time Polling Service (ertps) Periodic variable-size packets, e.g. VoIP Real-time polling service (rtps) Periodic variable-size packets, e.g. MPEG stream Non-real-time polling service (nrtps) Delay-tolerant streams, minimum throughput, e.g. FTP Best Effort (BE) No QoS requirements, e.g. HTTP 13