WI-MAX
GROUP MEMBERS
SHAHEER SHAHBAZ HYDER AIBAD AHMED ALI HABIB USAMA AHFAZ
CONTENTS
INTRODUCTION WIMAX
ARCHITECTURE QOS CLASSES MULTIPLEXING TECHNIQUES MODULATION SCHEMES WIMAX RADIOS APPLICATIONS
INTRODUCTION
BACKGROUND PROJECT DEVELOPMENT ON WIMAX WAS START IN 1998. WHY WIMAX????? Wi-Fi signals can not cover more than a hundred meters. Both LOS and NLOS support. Higher data rate than former technologies. Fewer base stations.
CONT.
WIMAX refers to interoperable implementations of the IEEE 802.16 family of wireless-networks standards ratified by the WiMAX Forum. There were some earlier version of Wimax that were used for testing purposes: 802.16a ,802.16b ,802.16c .
The current versions are 802.16d(FIXED) and 802.16e(MOBILE).
CURRENT DEPLOYMENT IN PAKISTAN:
Pakistan is the first country with worlds largest nationwide installed WiMAX network
Providers: Wi-Tribe, Wateen (3.5GHz), Mobilink Infinity, Qubee.
WiMAX could potentially be deployed in a variety of spectrum bands: 2.3GHz, 2.5GHz, 3.5GHz, and 5.8GHz
Operates in both licensed and un-licensed bands
WIMAX NETWORK CHARACTERISTICS
There are two scenarios for a wireless deployment: point-topoint and point-to multipoint.
Point to Point (P2P): Point to point is used where there are two points of interest: one sender and one receiver. As the architecture calls for a highly focused beam between two points range and throughput of point-to point radios will be higher than that of point-to-multipoint products.
CONT...
Point-to-Multipoint (PMP):
One base station can serve hundreds of dissimilar subscribers in terms of bandwidth and services offered.
LINE OF SIGHT (LOS) OR NON-LINE OF SIGHT (NLOS):
WiMAX functions best in line of sight situations. Buildings between the base station and the subscriber diminish the range and throughput, but in an urban environment, the signal will still be strong enough to deliver adequate service.
WiMAX ability to deliver services non-line-of-sight, the WiMAX service provider can reach many customers in high-rise office buildings to achieve a low cost per subscriber because so many subscribers can be reached from one base station.
WIMAX ARCHITECTURE END-TO-END REFERENCE MODEL
R2
R1 MSS ASN
R3 CSN
R4
NSP
Another ASN
ASP Netw ork OR Internet
NAP
DECOMPOSED ASN INTO BS AND ASN GW
ENTITIES
CPE OR MS
CPE and MS are end-user products which integrates with user devices Like laptops, mobile phones. it also includes USB modem, PCMCIA cards Can be fixed or mobile
BASE STATION
It provides connectivity to the consumer equipments Base station consist of wireless electronic tower Coverage area theoretically up to 50km but practically 10 km Additional functions are: handoff triggering, QoS policy enforcement, DHCP etc BS can be point-to point or point-to-multipoint BS are LOS as well as NLOS
ENTITIES OF THE WIMAX NETWORK
ASN: Access Serving Network
Logical representation of the functions of a NAP, e.g. 802.16 interface network entry and handover Radio Resource Management & Admission ctrl. L2 Session/mobility management QoS and Policy Enforcement Foreign Agent (FA) Forwarding to selected CSN
ASN-GW
Access service network-Gate Way acts as a layer 2 traffic aggregation points within an ASN. management, network optimization, and forwarding of all subscriber traffic, routing to the selected CSN , AAA client functionality.
CSN
Connectivity
service network provides: AAA servers that support authentication for the devices Operations tools IP & traffic management QoS & Policy Pre paid billing Billing control support for roaming between different NSPs
CONT....
AUTHENTICATION, AUTHORIZATION AND ACCOUNTING
AAA refers to Authentication, Authorization and Accounting. The AAA server provides the following services to WiMAX:
Authentication Services
These include MS, user, or combined MS and user authentication. These include the delivery of information to configure the session for access, mobility, QoS and other applications. These include the delivery of information for the purpose of billing (both prepaid and post paid billing) and information that can be used to audit session activity by both the home NSP and visited NSP.
Authorization Services
Accounting Services
INTERNETWORKING WITH 3GPP
Scope:
WiMAX-3GPP Interworking refers to the integration of a WiMAX Access Network to an existing 3GPP core network. Home AAA
GCSN Internet Billing Server PDG WAG 3GPP Core Network WiMAX Network Service Provider SGSN RNC 3GPP Access Network Loosely-Coupled Internetworking Local AAA Home Agent
WiMAX ASN
WiMAX Base Stations 3GPP Card WiMAX Card
UE
WIMAX REFERENCE POINTS
QOS CLASSES
Five QOS services are supported in WIMAX:
UGS (Unsolicited Grant Service) RT-VR (Real-Time -Variable Rate Service) NRT-VR (Non-Real Time -Variable Rate service) BE (Best Efforts) ERT-VR (Extended Real-Time Variable Rate)
UNSOLICITED GRANT SERVICE (UGS)
support real-time data streams consisting of fixedsize data packets issued at periodic intervals
Such as T1/E1 and Voice over IP without silence suppression
VoIP
REAL-TIME POLLING SERVICE (RTPS)
support real-time data streams consisting of variable-sized data packets that are issued at periodic intervals
Such as moving pictures experts group (MPEG) video.
NON-REAL-TIME POLLING SERVICE (NRTPS)
support delay-tolerant data streams consisting of variable-sized data packets for which a minimum data rate is required
such as FTP
BEST EFFORT (BE)
support data streams for which no minimum service level is required and therefore may be handled on a space-available basis.
EXTENDED REAL-TIME VARIABLE RATE (ERT-VR) SERVICE
support real-time applications with variable datarates, which require guaranteed data and delay, for example VoIP with silence suppression.
MULTIPLEXING TECHNIQUES
OFDM OFDM divides the bandwidth into multiple frequency sub-carriers. In OFDM sub-carriers are orthogonal to each other. OFDM also uses multiple sub-carriers but the sub-carriers are closely spaced to each other without causing interference, removing guard bands between adjacent sub-carriers. For fixed devices Orthogonal sub carriers produce no signal power in adjacent sub carriers
BASEBAND OFDM SYSTEM
CONT....
As a reminder, IFFT (Inverse Fast Fourier Transform) is used in a WiMAX transmitter to create an OFDM waveform from modulated data streams, while FFT (Fast Fourier Transform) is used in a WiMAX receiver to demodulate the data streams.
WHY IS OFDM SO POPULAR FOR NEW BROADBAND SYSTEMS?
Most broadband systems are subject to multipath transmission Conventional solution to multipath is an equalizer in the receiver With OFDM there is a simple way of dealing with multipath relatively simple DSP algorithms. It uses cyclic prefix to avoid residual ISI
If multipath delay is less than the cyclic prefix -no intersymbol or intercarrier interference -amplitude may increase or decrease
OFDMA:
OFDMA employs multiple closely spaced sub-carriers, which are divided into groups of sub-carriers. For mobile services Point-to-point systems are OFDM, and do not support OFDMA. Point-to-multipoint fixed and mobile systems use OFDMA.
CONT....
(OFDMA) is a multi-user version of the popular (OFDM) digital modulation scheme Assigns different subset of sub-carriers to individual user
Bandwidth options 1.25, 5, 10, or 20 MHz Entire bandwidth divided into 128, 512, 1024 or2048 sub carriers
SOFDMA:
SOFDMA is used for mobile Wi-Max mode. It adjusts the size of FFT while fixing the sub-carrier frequency Smaller FFT size is given to lower bandwidth channels, while larger FFT size to wider channels Capacity of each individual sub-channel remain constant By making the sub-carrier frequency spacing constant, SOFDMA reduces system complexity of smaller channels and improves performance of wider channels.
CONT....
SUB-CHANNELIZATION
Defines sub-channels that can be allocated to subscriber stations (SSs) Depends on :
Channel Conditions Data requirement
Base Station (BS) can allocate :
more transmit power to user devices (SSs) with lower SNR like for indoor SSs. less power to user devices with higher SNR.
Subchannelization in the uplink can save a user device transmit power because it can concentrate power only on certain sub-channel allocated to it.
Picture. Uplink Subchannelization in WiMAX In OFDM, only one SS transmits in one time slot. In OFDMA, several SS's can transmit at the same time slot over several sub-channels.
MODULATION SCHEMES
In Wimax the modulation schemes used are: Qpsk (Quadrature Phase Shift Keying) QAM-16, 64, & 256
QPSK uses four points on the constellation diagram In QPSK the phase is changed in 4 ways for sending data bits. QPSK can encode two bits per symbol.
CONT....
QAM is a technique in which the amplitude and phase varies simultaneously for sending higher data rate QAM is a combination of ASK and PSK.
In QAM-16, 4 bits are send on each single change with the phase change of 22.5 degree In QAM-64, 6 bits are send on each single change with the phase change of about 5.5 degree Same as for QAM-256 , 8 bits are send.
Constellation diagram for QAM-16 and QAM-64
WI-MAX RADIOS
A radio contains both a transmitter (sends) and a receiver (receives).
WiMAX antennas, just like the antennas for car radio, cell phone, FM radio, or TV, are designed to optimize performance for a given application.
OMNI DIRECTIONAL ANTENNAS
Omni directional antennas are used for point-to-multipoint configurations. Omni directional antenna broadcasts 360 degree from the base station. Omni directional antennas are good for situations where there are a lot of subscribers located very close to the base station.
SECTOR ANTENNAS
A sector antenna, by focusing the beam in a more focused area, offers greater range and throughput with less energy. Many operators will use sector antennas to cover a 360-degree service area rather than use an omni-directional antenna due to the superior performance of sector antennas over an omni-directional antenna.
PANEL ANTENNAS
Panel antennas are most often used for point-to-point applications Panel antennas are usually a flat panel of about one foot square.
APPLICATIONS
WIMAX VOIP
Voice over Internet Protocol (VoIP) offers a wider range of voice services at reduced cost to subscribers and service providers alike. The diagram below illustrates a typical solution where a WiMAX service provider can obtain wholesale VoIP services (no need for the WiMAX service provider to install and operate a VoIP soft switch) at about $5/number/month and resell to enterprise customers at $50.
