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wiMAX means worldwide interoperability for microwave accesswi .It based on the

IEEE802.16protocol is a broadband wireless technology applied to the Metropolitan Area

Network(MAN).it complies the Broadband & wireless trend.it features the orthogonal

Frequency division Multiplex Access(OFDMA),multiple input multiple output (MIMO) &otheradvanced technologies to maintain its broadband advantage.wimax called 3.5G or 4G

technology.it has become the 4th

standard of 3G technology in October of 2007.wimax provide a

range of up to 31 miles,which can provide both campus level network connectively & a wireless

last mile approach that can bring a high speed network &internet service directly to customer.this

is especially usefull in areas where the local telephone company may need a long time broadband

service & those areas that were not served by cable . For the dramatic change of the demand of

wireless access. Wimax has become the big issue considering its performance and efficiency.

The multipath effects and the co-channel should be considered with great importance to ensure the high

data rate and the effective use of the network. In addition, The high gain and the high coverage of the

Wimax to a desired direction of high traffic with reducing the dead spot should be given the high priority

which is the main objective of this thesis.

802.16d Fixed Broadband radio access standard: It specifies the air interface layer

between the fixed access terminals and

the BTS.

802.16e Mobile Broadband radio access standard: It supports the mobile stations.

Moreover it supports both the fixed broadband radio access system and mobile broadband rad


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Global Spectrum Distribution of WiMAX:

Primary frequency bands:

2.3G: 2.3 - 2.4 GHz

2.5G: 2.496 - 2.690 GHz

3.5G: 3.4 - 3.6 GHz

QoS - Based Services:

Unsolicited Grant Service(UGS): VoIP (without silence suppression)

Extended Real-time Polling Service(ertPS): VoIP (with silence suppression)

Real-time Polling Service(rtPS): MPEG video

Non-Real-time Polling Service(nrtPS): FTP service

Best Effort(BE): Network browse, e-mail

Network Elements of WiMAX:

MSS (Mobile Subscriber Station)

ASN (Access Service Network): The ASN consists of the Base Station (BS) and the Access Service Network-Gateway(ACN-GW). The ASN manages the IEEE802.16e air interface and enables the MS to access multiple CSNs.

CSN (Connect Service Network): The CSN is connected to the internet, ASP, PLMN, and other networks. It provides

Authentication, Authorization and Accounting (AAA), roaming between different NSPs (Network Service Providers), IP addressmanagement, location management, mobility management, connection for multiple services, policy management, and QoSmanagement.

NAP (Network Access Provider)

NSP (Network Service Provider)

Networking features of WiMAX:

Independent networking

Hybrid networking with 2G/3G

Easy to construct the network

Low cost

The above figure shows the management reference model for BWA (Broadband Wireless Access ) networks. This

consists of a Network Management System (NMS), some nodes, and a database. BS and SS managed nodes

collect and store the managed objects in an 802.16 MIB format. Managed objects are made available to NMS'

using the Simple Network Management Protocol (SNMP).

When a customer subscribes to the WiMax service, the service provider asks the customer for the service flow

information. This would include number of UL / DL connections with the data rates and QoS parameters. The

customer also needs to tell the kind of applications that he proposes to run.


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Figure 2: WiMax Management Information Base [Intel.Com]
http://www.intel.com/http://www.intel.com/http://www.intel.com/http://www.intel.com/


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WiMax Competing Technologies

As we learnt in the previous pages, that WiMax was formed to

complement Bluetooth and WiFi technologies, let us look at the

differences in each of these:

Parameters WiMax WLAN Bluetooth

Frequency 2 ~V 11

GHz

2.4 GHz Varies

Range ~31 miles ~100 metres ~10 metres

DataTransfer

Rate

70mbps 11 ~V55mbps

20 ~V55mbps

Users 1000s > 10 > 10

Table 1 ~V Difference between WiMax, WLAN and Bluetooth [J avvin.Com]

The 802.11 is based on a distributed architecture, whereas, WiMax is based on a centrally controlled architecture.

In this the scheduler residing in the Base station (BS) has the complete control of the wireless media access.

WiMax can support multiple connections conforming to a set of QoS parameters and provides the packet classifier

ability to map the connections to many user applications and interfaces.

WiFi and WiMax may end up complementing each other, but a new technology, IEEE 802.20, might give them both a

run for their money. IEEE 802.20 standard like the 802.16 is aimed at wireless high-speed connectivity to mobile

consumer devices like cellular phones, PDAs and laptops. It will operate in the 500 MHz ~V 3.5 GHz and is led by

Flarion Technologies and ArrayComm.

Benefits;

Benefits to Component Makers:o Creates a volume opportunity for silicon suppliers.
http://www.javvin.com/http://www.javvin.com/http://www.javvin.com/http://www.javvin.com/


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Benefits to Equipment Makers:o Innovate more rapidly because there exists a standards-based, stable platform upon which to rapidly add new

capabilities.

o No longer need to develop every piece of the end-to-end solution.

Benefits to Operators:o A common platform which drives down the cost of equipment and accelerates price/performance improvements

unachievable with proprietary approaches.o Generate revenue by filling broadband access gaps.o Quickly provision T1 / E1 level and "on demand" high margin broadband services.o Reduce the dollar risk associated with deployment as equipment will be less expensive due to economies of

scale.

o No longer be locked into a single vendor since base stations will interoperate with multiple vendors' CPEs.

Benefits to Consumers:o More broadband access choices, especially in areas where there are gaps: worldwide urban centers where

building access is difficult; in suburban areas where the subscriber is too far from the central office; and in rural

and low population density areas where infrastructure is poor.

o More choices for broadband access will create competition which will result in lower monthly subscriptionprices.

Wimax Limitations

WiMAXis a great technology for next generation with potential applications such as cellular backhaul, hotspot, VoIP mobiles and broadband

connection but it have some limitation as under.

Low bit rate over Long distance

Wimax technology offering long distance data range which is 70 kilometer or 30 miles and high bit rate which is 70Mbit/s.thats good but both

features doesnt work together when we will increase distance range the bit rate will decreased and if we want to increase bit rate then we

should reduce the distance range.

Speed of connectivity

The wimax other drawback is that any user closer to the tower can get high speed which is up to 30Mbit/s but if a user exist at the cell edge

from the tower can obtain only 14Mbit/s speed.

Sharing of bandwidth

In all wireless technology the bandwidth is shared between users in a specified radio sector. Therefore functionality could go down if more

than one user exists in a single sector. Mostly user have a range of 2- to 8 or 12 Mbit/s services so for better result additional radio cards

added to the base station to boost the capability as necessary.


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WiMax over Wi-Fi

Any one can build up a wifi network but to set up a Wimax network is really expensive so it is very hard for every one that they pay large

mount for the setup and frequency license of Wimax in a region.

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