Professional testing is key in ensuring high QoE for VoLTE

This guest blog post was written by Kai Ojala, CTO, Anite Network Testing

The requirement for VoLTE is to offer high-quality voice calls and video calls, which as a baseline requires wide LTE coverage. LTE networks fulfill this aspect – especially lower carrier frequencies are deployed globally (e.g. 700 and 800 MHz frequency bands). Operators will benefit from customers switching to VoLTE services by harmonizing voice services and getting better capacity out of the spectrum.
Voice calls in LTE networks can be handled using Circuit Switched Fallback (CSFB) and Voice over LTE (VoLTE). CSFB provides a mechanism to transfer an initiated voice call to legacy circuit-switched networks. VoLTE, on the other hand, is a fully packet switched technology which uses Voice over IP (VoIP) technologies. With the SR-VCC functionality voice calls made with VoLTE can be switched over to legacy networks when the user moves out of the LTE network coverage.

LTE Spectrum bands foxing networks and devices alike

Paul Beaver, products director at Anite

This is a guest blog post from Paul Beaver, products director at Anite. Anite has been shortlisted at the LTE Awards 2012 in the Best Test/Measurement LTE Product category. 

There will be one billion HSPA and LTE connections by the end of March and that number will double in two years, according to Informa Telecoms & Media. But the roll-out of LTE is not without its challenges. As carriers and handset providers navigate the path to 4G mobile services, not only do they have to cope with multi-technology networks, but also multiple frequency bands. Global LTE frequency allocation will differ because of diverse national regulatory positions on the issue. Current 3GPP specifications for LTE define over 30 potential bands for the technology. This is an inheritance of the different allocations issued by regulators and the ability of LTE to be deployed in a much wider range of frequencies than prior mobile standards.

Incorporating technology to cope with multiple LTE frequencies and supported bandwidths presents a major challenge to operators and manufacturers. One example of the complex problems that LTE brings is the ability to roam onto different international LTE networks, each with their own varied make-up and performance nuances. For instance, French incumbent operators are in the process of bidding for 4G spectrum in the 2.6GHz band, whereas networks in the USA have deployed LTE in the 700MHz–800MHz frequencies. Networks utilising 2.6GHz or 700MHz-800MHz frequencies for LTE could mean that subscribers may have problems connecting to the network when roaming.

Operators and manufacturers will be able to overcome the challenges of supporting multiple LTE frequency bands by developing a comprehensive quality assurance system, based on laboratory based device testing. However, I believe that field testing LTE devices alone is not a practical solution, as it requires a significant amount of time, prohibitively high cost levels and is not repeatable. Imagine replicating a real-life scenario in which a business user is downloading a file on their device, while making an essential voice call, but moving from a 3G coverage area to a 2G cell. Test engineers are not able to fully control such field tests, repeat them exactly or account for changes in RF conditions and network configurations.

Fortunately lab-based LTE device testing does not rely on any live network dependency, and can be optimised to match the profile of an LTE environment and the range of different LTE frequencies. Live LTE device tests can be reproduced in the laboratory from roaming through to data throughput and specific user scenarios, plus many more. Precise examinations can be undertaken at any time, with no actual impact on network subscribers or service, not to mention the lower costs and significant testing ease that the lab environment unlocks.

The LTE World Summit is taking place on the 23-24 May 2012 CCIB, Barcelona, Spain. Click here to register your http://ws.lteconference.com/interest.