Subject : Mobile Communication

Topic : 4G Wireless Networks

Difficulty : Medium

WiMAX:

i. The ‘World Interoperability for MicroAcess, Inc. (WiMAX)’ forum, an industry group, focuses on creating advanced technology solution for high speed wide area internet access.

ii. The WiMAX product certification program ensures interoperability between WiMAX equipment from vendors worldwide.

iii. WiMAX can serve as a backbone for 802.11 hotspots for connecting to the internet. Alternatively, users can connect mobile devices such as laptops and handsets directly to WiMAX base stations. Mobile devices connected directly can achieve a range of 4 to 6 miles.

iv. There are 2 types of WiMAX, fixed WiMAX(IEEE 802.16d-2004) and mobile WiMAX(IEEE802.16e-2005). Fixed WiMAX is a point-to-multipoint technology, whereas mobile WiMAX is a multipoint-to-multipoint technology, similar to that of a cellular infrastructure.

Some of the salient features supported by WiMAX are:

i. High data rates: - WiMAX can typically support data rates from 500 Kbps to 2 Mbps. - The inclusion of multi-input multi-output(MIMO) antenna techniques along with flexible sub-channelization schemes, advanced coding and modulation all enable mobile to support peak downlink data rates of 63 Mbps per sector and peak uplink data rates of up to 28 Mbps per sector in a 10 MHz channel.

ii. Quality of service (QoS):

• WiMAX has clearly defined QoS classes for applications with different requirements such as VoIP, real time video streaming, file transfer and web traffic.

iii. Scalability:

• Mobile WiMAX is designed to able to work in different channelization from 1.25 to 20 MHz to comply with varied world-wide requirements.

iv. Security:

• There is support for diverse set of user credentials like SIM/USIM cards, smart cards, digital certificates, username/password schemes.
• All this is based on relevant ‘extensible authentication protocol (EAP)’ methods for credential type.

v. Mobility:

• Mobile WiMAX supports optimized handoff schemes with latencies less than 50ms to ensure that real time applications such as VoIP can be performed without service degradation.

• Flexible key management schemes assume that security is maintained during handoff.