The latest technology to hit the telecommunications market this year is UMA. It still isn't available to consumers as yet but the pressure to do so is escalating because major operators and manufacturers have just started to implement and test UMA. Apart from the financial benefits, service providers want to deploy UMA technology because it will enable subscribers to seamlessly roam and handover between cellular networks (wide area networks) and unlicensed wireless networks (local area networks) using existing dual-line mobile handsets. Therefore, as users transition between networks, they can take advantage of a consistent user experience for their voice and data services.
To those of you who are unaware of this technology, UMA is an abbreviation for Unlicensed Mobile Access - and it is the technology or telecommunication system that provides users access to GSM, GPRS (or UMTS) mobile services over private and public unlicensed spectrum technologies such as Bluetooth and 802.11. You may ask why this is needed, but the simple answer is that the introduction of UMA further provides the technological convergence of mobile, fixed and internet telephony networks. More specifically, it is the mobile operators who benefit from such convergence because it allows them to deliver voice, data and IMS/SIP applications to mobile phones on local networks.
Generic Access Network (GAN), was formerly known as UMA, until it was adopted by the 3GPP in 2005 for 3GPP Release 6 (specification TS 43.318). The 3GPP organisation adopted UMA as a result of enormous efforts by UMA participating companies (leading operators) who jointly initiated specifications for this technology. These leading operators and manufacturers include, Alcatel, BT, Cingular, Kineto Wireless, Motorola, Nokia, Nortel Networks, Siemens, Sony Ericsson, and T-Mobile (US).
To understand how UMA technology works, we need to look at the architecture of the system.
Diagram 1: Architecture of UMA technology
According to Diagram 1, when a UMA enabled, dual-mode handset moves within range to an unlicensed wireless network, it connects to the UMA Network Controller (UNC) over the broadband IP access network to be authenticated and authorised to access GSM voice and GPRS data services. When authentication and authorisation is approved, the subscriber's current location information stored in the core network is updated. Thus, all voice and data traffic is routed to the handset via the Unlicensed Mobile Access Network (UMAN) rather than the RAN. There are two processes in UMA technology that are completely transparent to the subscriber and they describe what happens when a user moves (i) outside and (ii) within the range of UMA.
(i) When a UMA enabled subscriber moves outside the range of an unlicensed wireless network to which it is connected, the UNC and handset facilitate roaming back to the licensed outdoor network. This process is called ROAMING.
(ii) The other scenario is when a subscriber is camped on the licensed network with an active voice call or data session and when it comes within range of an unlicensed network, the handset can automatically HANDOVER between access networks with no drops or disruptions respectively.
Diagram 2: UMA Functional Architecture
By looking at diagram 2, we can further understand how UMA technology provides alternative access to existing GSM and GPRS core network services via IP-based broadband connections. To achieve seamless user experience, the UMA participating companies needed to introduce specifications that defined a new network element, i.e. UNC, and associated protocols to provide secure transport of GSM and GPRS control signalling and user plane traffic over IP. As a result, it was designed so that the UNC interfaces into the core network via existing 3GPP specified A/Gb interfaces.
Now, before we glance at the benefits of UMA, there is one crucial issue that needs to be discussed. UMA may probably be perceived as threat to the mobile network operators but it isn't, because UMA traffic will still be routed through the conventional mobile network elements, allowing network operators to bill and control WiFi use. Moreover, when the dual-mode mobile phone is on WiFi, a VPN (IPSec tunnel) is created from the handset to the controller in the mobile network. Thus, all the voice and data traffic travels over the VPN.
The advantages for UMA are listed below:
- UMA offers seamless delivery and transition (roaming and handover) of mobile and voice and data services between unlicensed and licensed wireless networks
- UMA provides the same mobile identity on Cellular RAN and unlicensed wireless networks and presents no impact to operations of the cellular RAN
- It preserves investment in existing/future mobile core network infrastructure
- It also offers security that is equivalent to current GSM mobile networks
The disadvantages of UMA are not many but thus have to be listed as well.
- Battery life of handsets need to be drastically improved at present because a dual-mode mobile phone needs to scan for 2 different types of networks at all times, i.e. cellular and WiFi. So, it must have 2 radios on board.
- At times of communication, the user may be charged for services that can sometimes be for free. For example, if all the data from the handset goes through the carrier's servers and is chargeable, then subscribers might be upset as to why they get charged for data that goes through their internet connection, when instead they can use laptops (or other devices) for free.
Along with companies such as British Telecom, O2 and Sony Ericsson, Nokia are one of the major participants of the Unlicensed Mobile Access (UMA) standard. Presently they are conducting a public study in the city of Oulu, Finland. The study began on the 27th July 2006 and is expected to last for 2 months. Oulu is a city with many WiFi hot-spots which makes it idle for the study. Fifteen families will participate using the new Nokia 6136 UMA enabled phone. The Nokia 6136 is a quad-band GSM and 802.11 b/g wireless phones with support for seamless hand-over from between the two radio technologies.Nokia believes that UMA provides network operators with the ability to expand their networks without the need to deploy expensive cellular base stations? UMA will give mobile operators the ability to move into areas once considered difficult for a cellular based network, such as commuter subway networks.
Fixed operators have been losing ground in the voice communications market for a long time. Mobile operators have become almost as cheap as fixed line operators and with the advent of VoIP services, fixed voice lines are becoming less and less necessary. It has been much easier for a mobile operator to moved into the domain of the fixed operator then it has the over way.Fixed operators such as BT have only recently began to realize the asset which they hold. Strangely enough this is the fixed network. Fixed networks are able to provide superior bandwidth versus cost against any wireless network.
BT are aware of this and understand that for any UMA network to be successful it must be based on a fixed network with a good Quality of Service (QoS). With this in mind, BT and over fixed network operators see the advent of UMA as a chance to reclaim some of the ground lost to mobile operators. BT have launched a new service in the UK called Fusion BT and have adopted a Mobile Virtual Network Operator (MVNO) approach and for its UMA offering, by using its own fixed network to route calls through the Internet whilst at home and then using the mobile operators network whilst away from home.
Services that combine both WiFi and cellular technology, including UMA and equivalent technologies for the CDMA camp, could potentially contribute massive revenues for major operators worldwide. However, the lingering question would be whether UMA would be enticing enough for today's consumers.