Voice over WiMAX

Next generation wireless solution
WiMAX, the solution of choice for next generation broadband, is designed from its core to deliver large throughput with a variety of applications - IP connectivity, voice and video. As both a reliable wireline replacement solution and next step to legacy mobile, it has the ability to support providers in offering first line (or first device) replacement, through product bundles or standalone services. In today’s competitive telecommunications landscape, it has become imperative to deliver a total product portfolio on a broadband basis, even in markets where liberalization processes moved slower than in the leading economies.
Technology for broadband data and voice

The WiMAX technology, and more importantly the functionalities it provides, constitute the opportunity for service providers to cover all types of usage behavior, ranging from typical fix usage in captive locations to access while being on the move. This unique attribute allows service providers to design product bundles including voice and compete not only with legacy incumbents and other wireline operators, but also have competitive offerings for users requiring different types of wireless freedom. WiMAX as a data-centric technology is also going to meet expectations of the next generation of voice customers, who have positive mind set towards voice over IP and communicate using such devices like USB phones, laptops and other portable multimedia devices. In fact starting from the year 2008, notebooks and gradually other consumer electronic devices will have WiMAX chips embedded in them and will become a perfect fit for all operators planning to roll-out networks of the 802.16 standard.

Support for new wave mobility
As an always-on technology, WiMAX is not only the solution of choice for instant internet access, but also well suited for permanent voice availability. From the end-user device perspective, the voice connectivity is being assured based on a softphone-client solution residing as an application, like in a typical PC-based environment. Current trends oriented towards unification of mobile telephony and computer devices result in new converged solutions for the mass market, called ultra-mobile PC. These multimedia devices will have the ability not only to access various data networks, but also serve voice in a data-based environment. This represents another fit with a wireless broadband network that can not only carry volume but is also capable to support seamless mobility.

The benefits for the customers seems therefore to be assured in the short as well as in the long term. Not only are solutions being developed that bring services and advantages to existing alternatives, but the next-wave functionalities supporting more technology-oriented societies are rapidly coming to market.

Practical implementation
Voice over WiMAX has become already a real life experience and a viable business. In Central and Eastern Europe, WiMAX Telecom, a leading WiMAX service provider, delivers voice services along with its broadband offering over its 802.16 network. The service, branded WiMAX FON, is offered currently as a first line replacement solution, allowing customers to switch completely from the incumbent operator. The service also offers number portability as an additional feature of the package. On the technical level, the service is based on SIP protocol, with an end-to-end quality assurance. This is secured due to the following environmental factors:
full IP supervision within own network - there is no transmission through public Internet),
no packet compression, allowing for superior sound quality outperforming on comparative level the abilities of mobile networks,
voice traffic prioritization.

Both data and voice traffic are transmitted within the fully owned and managed IP network, that has MPLS (MultiProtocol Label Switching) implemented. Furthermore in order to provide the necessary resources for the voice transmission quality, a vendor specific dynamic resource allocation protocol and IP ToS (Type of Service) within the MPLS network are also implemented. The standard for audio companding applied in the network is G.711, which provides an 8 kHz sampling frequency and 64 kb/s bitrate.

For voice termination, the infrastructure is interconnected with a typical “anchor network”, which is usually the network of the incumbent, and also with wholesale operators which provide interconnectivity and termination services on an international level. It is important to emphasize the portability feature, which is one of the key functionalities for customers switching from other networks, but insisting on having still the same telephone number. The technical feasibility for this can be assured only when interconnected with the incumbent or an interconnect partner, that also provides portability outsourcing.

The competitiveness of the voice services is also enhanced thanks to additional on-top options. One of the is the so called customer self-care, which enables customers to manage their broadband and voice services conveniently on-line and 24 hours a day, thus being not dependent from any call center or legacy type helpdesk. From the voice service perspective the self-care system allows to obtain electronic invoices, analyze real-time billing, manage customer data, reroute incoming connections, etc.

The implementation of voice services in WiMAX networks has delivered numerous benefits for customers. These include:
possibility for a complete switch-off from incumbent operator,
one voice and data package,
no need for wireline infrastructure for all services,
flexibility thanks to number portability (no need to change existing number),
savings due to product bundle and lack of legacy copper wire subscription.