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Building an end-to-end architecture that supports fixed mobile convergence

Posted: 08 Sep 2005 ?? ?Print Version ?Bookmark and Share

Keywords:fixed mobile convergence? fmc? agere systems? ericsson?

Network convergence could be further divided between the access network and the core network. Network convergence means the same network will be used for fixed and mobile services and by both types of operators. Currently, network service providers could, in principle, share transmission/transport infrastructures.

Optical Sonet/SDH/WDM and microwave transmission infrastructures could be common for fixed and mobile operators, thereby making convergence at the "physical" layer feasible today. Furthermore, this convergence could be extended for packet services with operators sharing ATM and IP network infrastructures.

The new notion of network convergence is that service providers should be able to share network infrastructure above and beyond the straight-forward transmission/transport "pipes" and extending to network control and intelligence. In fact, the architecture that will enable this network convergence is commonly referred to as a layered architecture (see Figure 1).

Figure 1: The layered architecture concept

The layered architecture concept introduces common connectivity and control layers for all access types and all services. Access networks (i.e., DSL, GSM Radio Access Network, WiMAX, etc.) may require a core network adaptation due to transport or protocol incompatibilities. These elements are called media gateways.

Access methods have been traditionally positioned with either fixed or mobile networks. Recently, however, newly introduced access methods such as WLAN, WiMAX and Unlicensed Mobile Access (UMA) can be associated with either fixed or mobile access.

On the services side, voice remains the most obvious and widely used service in both fixed and mobile networks. Voice service is, in effect, a convergent service because it can be offered across both networks. Other services, however, such as short messaging service (SMS) and instant messaging (IM), have been associated with specific networks, e.g. mobile or fixed.

The notion of service convergence is to introduce new services in a transparent way over both networks; as well as introduce combined services, such as new services that consist of two or more basic services.

Network architecture

A variety of access technologies, both wireline and wireless, have been adopted, or, they are under development in standards bodies or other forums. These technologies address issues such as bandwidth, applications, and quality of service.

In the wireline arena there are access technologies such as xDSL, DOCSIS and FTTH that deliver similar or even higher bit rates to users on telephony DSL lines, coaxial cables for TV distribution, and optical fibers, respectively.

Some of the access technologies that will play a vital role in a fixed-mobile convergence environment include:

Digital subscriber line (DSL) has been around for several years, and it continues to evolve. The most recently standardized (ITU G.992.5) asymmetric flavor is called ADSL2+. The new standard promises to deliver up to 24Mbit/s downstream, and up to 3 Mbit/s upstream. Because of its high potential bandwidth, DSL is one of the most important access methods for true converged multimedia applications in cases where good quality copper is available.

Wireless local area network (WLAN) access provides a low-cost, high-bandwidth method for data today, and other multimedia applications in the future. Operators in the North America, Europe and Asia are offering WLAN access in hot-spots for Internet access. Voice over IP (VoIP) is soon to come. Long-awaited roaming with 3G networks makes WLAN a key access technology for fixed-mobile convergence. A user with WLAN access either at home, or at an enterprise or pubic location, could be connected through appropriate multi-access (WLAN and cellular) terminals to the Internet, to the PSTN, or to mobile network(s).

Wireless Interoperability for Microwave Access (WiMAX) can be thought as an initiative to provide cost-effective interoperable products and solutions for broadband wireless access (BWA). More specifically, IEEE 802.16 has enhanced its specifications to accommodate interoperable products in the 2 - 11GHz frequency band range. The first specification IEEE 802.16-2004 is now ready, and WiMAX certified products are expected in 2005. Completion of 802.16e, which will accommodate mobility, is expected in 2005.

Unlicensed Mobile Access (UMA) is a set of specifications created by a group of vendors and operators to create bearer-agnostic access to cellular networks. In the proposed initial version of the standard, a mobile device is equipped with a non-cellular radio and connects to an UMA Network Controller (UNC).

Using IPSec, it creates a secure tunnel into the cellular network. Using this approach, the cellular network utilizes existing protocols for AAA as defined in 3GPP without the need to define any new protocols. A recent important development is the inclusion of the UMA concept in the 3GPP R6 specifications under the term Generic Access Network (GAN) in TS 43.318 within the GERAN set of standards.

Core network technology development

Until recently, wireless, wireline, data and cable TV networks have been separate from one another. Next-generation solutions represent a more efficient way to build networks using a common multiservice layered architecture. They will have a service layer, a control layer, a backbone layer and access layer.

Having one converged network for all access types is a significant benefit of the layered architecture concept. It can improve service quality and allow the efficient introduction of new multimedia services based on IMS. Service providers can increase network efficiency using optimized transport and coding solutions and will not need the extra-capacity required when the networks are operated separately.

Significant cost savings can arise from having one network with fewer nodes and lower operating costs. From an investment perspective, it is possible to optimize use of control and media processing resources, reducing the need to replace technologies and the cost of network updates.

A converged network using IMS allows the following resources to be shared, regardless of service or access type:

- Charging

- Presence

- Directory

- Group and list functions

- Provisioning

- Media handling

- Session control

- Operation and management

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