Mobile operators must tackle the transition to next-generation Ethernet if they are to successfully meet consumer demands for new services, argues Vinay Rathore
Mobile operators are in a period of fundamental transition, as consumers increasingly demand access to personal high-bandwidth services while on the move. The growth of 3G data services, mobile broadband and the availability of powerful new mobile devices such as the Apple iPhone are placing significant strain on mobile networks and operators are investing in additional capacity to support this bandwidth explosion.
However, the operational costs associated with traditional mobile backhaul (defined as the access portion of the network transporting traffic between the mobile base station and gateways to the packet network and voice switched network) are increasing faster than the revenue generated by new data services. Until recently, most network operators have been trying to add backhaul capacity primarily by leasing additional TDM-based E1 circuits at a high cost. Worldwide, TDM backhaul accounts for 20 to 40 per cent of mobile network Operating Expense (OPEX). All this is untenable in a competitive market of shrinking average revenue per user (ARPU).
The challenge facing mobile operators is how to increase network bandwidth, both in terms of capacity and speed, while reducing the total cost of running the network and growing top line services revenue.
In the UK, for example, demand for mobile Internet services is increasing while the adoption of mobile broadband is heating up competition among fixed and mobile operators. Approximately one in eight UK consumers have either replaced their fixed-line Internet connection with a mobile alternative or chosen a mobile broadband service from the outset according to research published by YouGov. Similarly, Ofcom's latest Communications Market Report (August 08) found that two million people have already used mobile broadband via a dongle, 3G datacard or similar device, with sales reaching 133,000 from 69,000 between February and June this year alone.
In addition, a recent report from Neilson mobile highlighted that the UK has the second highest number of active mobile Internet users in the world (12.9 per cent), second only to the US. Furthermore, the availability of powerful new mobile devices such as the 3G iPhone are driving mobile Internet usage by promising consumers easier access to mobile business, personal and entertainment services. For example, 37 per cent of iPhone users watch video, 82 per cent access the Internet, 17 per cent stream music and 76 per cent send email on their phones according to Neilson Mobile.
Operators have been quick to capitalise on people's desire to access and download content off the Internet on their mobile phone, launching a suite of new services. A recent independent survey (June 2008) conducted on behalf of Quickplay, found that two in five people in the UK had already watched TV and video content on their mobile phone, with many now regularly using such services. 18 per cent of those that had tried a Mobile TV and video service watch on a weekly basis.
However, while mobile operators are continuously upgrading their wireless networks to support this bandwidth explosion, it's not just about adding capacity. In fact, network quality is the most important driver of satisfaction with the mobile Internet, accounting for 79 per cent of overall satisfaction according to Nielsen Mobile.
These trends highlight the need for mobile operators to invest in next-generation network infrastructure to accommodate increasing bandwidth demand and deliver a high quality user-experience while maintaining profitability.
Current networks were designed to transport voice traffic over Time Division Multiplex (TDM) networks with E1 circuits to provide backhaul transport from the base station to the network controller, and over SONET/SDH networks for voice traffic from the controller to a Mobile Switching Center (MSC). With the advent of 2.5 G mobile networks and the data services thereby enabled, the backhaul network has evolved to accommodate increased data traffic by including Frame Relay, ATM and IP, but in large part this data still travels over TDM circuits utilizing ATM/IMA.
The current TDM-based backhaul network is being overwhelmed by the rapid increase in bandwidth demand with the introduction of 3G (HSPA, EV-DO) and 4G (LTE, UMB, and WiMax) data services. For example, to ensure all users have access to Mobile TV services, the network must be scalable to support thousands of multi-cast video streams such as broadcast TV as well as uni-cast streams like You Tube.
As a result, mobile operators must reduce the cost-per-bit of data transport in the backhaul network while continuing to ensure voice quality, maintain carrier-grade Operations, Administrations, and Maintenance (OAM), and provide circuit-like resilience.
Carriers can take advantage of advanced Ethernet technology as a solution to challenges in the mobile backhaul network and reduce the dependency on E1 leased lines, and expensive SDH infrastructure. Carrier Ethernet is far more economical as it lowers the cost-per-bit and operational expenses while offering carrier-class management and Quality of Service with the right attributes. High-performance Carrier Ethernet solutions offer larger pipes - essentially, more bandwidth - to meet end-user bandwidth requirements while lowering the overall infrastructure cost and ensuring high quality of service. Using Ethernet, operators can scale network more easily to meet the demands of mobile services and applications without scaling costs. By building an Ethernet mobile backhaul, operators can burst up to the full speed and use the same circuit to carry different types of traffic. While there is still some concern regarding carrying time-sensitive traffic such as voice over Ethernet, the industry is working toward resolving this issue in multiple ways including developing TDM over Ethernet standards.
However, while advanced Ethernet technology provides a solution to backhaul problems, the backhaul network does not operate in isolation. To work efficiently and leverage Operational Expense (OPEX) advantages, the mobile core network must also evolve as the access network migrates to Ethernet. Building a Carrier Ethernet network infrastructure using standards defined by the Metro Ethernet Forum provides operators with long-term, low-cost strategy to replace their existing SDH infrastructure while maintaining carrier-class reliability.
However, as carriers have invested heavily in their current mobile networks, they cannot afford to simply tear out and replace current legacy radio infrastructure. It is crucial that their mobile backhaul and core network strategy still supports legacy traffic and service while allowing them to gradually transition to next-generation infrastructure that are more scalable and economical.
There is no ‘one size fits all' approach to building out an Ethernet backhaul network. Each tower has different requirements based on available infrastructure, bandwidth requirements, and geography. Most Ethernet backhaul networks will be a hybrid of fibre, microwave and copper. In addition, it is likely that operators will lease portions of their network and own portions in order to balance CAPEX and OPEX budgets. Additionally, operators will need to support TDM, ATM and Ethernet networks during the transition phase. With all of these varied requirements, operators must seek out vendors that supply a comprehensive Ethernet portfolio that can be gradually applied as the network demands evolve.
Fixed telecom operators are already benefiting from the migration from TDM-centric to next generation Ethernet centric networks. Mobile operators must manage this aggressive transition to next-generation Ethernet to maximise the investment in existing mobile and network infrastructures while maintaining a quality of service that minimises subscriber churn.
Vinay Rathore is Director of Product Marketing, EMEA, Ciena