Home North AmericaNorth America 2008 Mobile broadband needs microwave backhaul

Mobile broadband needs microwave backhaul

by david.nunes
Issue:North America 2008
Article no.:14
Topic:Mobile broadband needs microwave backhaul
Author:Philippe Dumont & Patrick Picquet
Title:VP, for Wireless Transmission; VP WTD North America
PDF size:324KB

About author

Philippe Dumont leads the Wireless Transmission Product Group of the Optics Division within Alcatel-Lucent’s Carrier Business Group. Prior to this, Mr Dumont led the Wireless Transmission Division of the Wireless Business Group and, earlier, the Wireless Transmission Division and the Wireless ETSI Business Unit. Mr Dumont joined the Alcatel Cable Group overseeing production on the shop floor. After a period spent outside Alcatel as a consultant in strategy and organization for Solving International, he came back covering several management roles in the Alcatel Audit Group, in the Fixed Wireless Access BU (LMDS), where he created and supervised all supply chain and customer services activities, and in the Optic Networks Division/Wireless Transmission Division overseeing Operations in France. Philippe Dumont holds an engineering degree from the Arts & Metiers and an MBA from Haute Etudes Commerciales (HEC) in Paris. Patrick Picquet is VP WTD North America at Alcatel-Lucent. He heads the North American Wireless Transmission Regional Support Center (RSC) within the Optics business of Alcatel-Lucent. The Wireless Transmission RSC is responsible for the Business Development, Network Engineering and Tendering of point to point microwave radio network solutions. Previously Mr Picquet led the Wireless Transmission Division Business Unit for North America within the Wireless Transmission Division of Alcatel-Lucent as well as General Manager responsibilities for Ferrocom a ferrite manufacturing business. Patrick Picquet holds B.S. in Electrical Engineering from the University of Texas at Arlington and an Executive MBA from Southern Methodist University.

Article abstract

A significant part of mobile network operators’ costs result from backhaul, the transportation of the signals from the radio base stations to the core network. Today, operators in the US use leased T1 fixed lines for backhaul. The move to 3 and 4G mobile networks will increase traffic and the T1s per cell site two to seven times. The number of cells needed will grow four times as will network costs, but revenues will remain flat; rapidly shrinking margins will drive operators to seek lower cost wireless backhaul solutions.

Full Article

For years, the US mobile operators have relied on leased T1 backhaul facilities to transport their voice services. Backhaul, transporting traffic from access networks back to the core network, is predominantly based on leased T1 circuits for US mobile operators. This solution has been driven by the availability of low cost leased line services, limited access to fibre, and by the misconception that microwave radios are complex, expensive or unreliable. New mobile broadband services will challenge this existing practice. Why will new wireless broadband services require US mobile operators to dramatically change the way they support their backhaul requirements? Compelling Event #1: EvDO evolution to RevB and UMTS evolution to HSDPA+ will increase cell site capacity from a few T1’s of voice traffic to 50MB of packet traffic. Relying on Leased T1 to support mobile broadband services disrupts the linear relationship between the mobile carriers’ operational expenses (OPEX) and call revenue. With no alternative the continuation of T1 circuits for backhaul will increase the overall T1 count per cell site from the current average of two to as much as seven T1s by the beginning of 2009 1. Leased T1 counts will continue to rise while the total revenue generated by the data transported will remain flat. Compelling Event #2: LTE cell sites will multiply by a factor of four The LTE mobile networks will need to increase their cell site density by a factor of about four compared to today’s architectures due to coverage and capacity constraints. Typical distances between LTE base stations will be 1.5 miles in dense metropolitan areas2. This increase in the cell density required will be driven by end user applications such as text messaging or video download and the need to meet the customer expectations while using these applications. Compelling Event #3: New services primarily packet based New mobile broadband services are packetized and seldom time sensitive in nature. These attributes permit the data to be transported more efficiently over native Ethernet than plesiochronous networks. Depending on the application3 efficiency can improve by 30 per cent or more. For this reason most 4G base station manufacturers will implement Ethernet connections as the primary interface. Providing the access backhaul with leased T1s will not be efficient or, in some cases, not possible in an all-Ethernet world. Three alternatives exist for transporting packet data – Ethernet over fibre, copper or microwave. All three of these solutions have advantages and disadvantages. No one solution is always right. However, only microwave offers the ability to wirelessly connect base stations eliminating right of way concerns, the high cost of trenching and fibre cuts due to backhoes. In the evolutionary path to 4G networks, microwave backhaul is a necessity. There are really two compelling reasons for a backhaul strategy based on microwave packet radio transport. Ethernet over copper or fibre will not meet all the needs of 4G networks. LTE networks need an access backhaul technology that can easily connect base stations to the transmission network quickly and at the right cost to maximise the operator’s revenue and quality of service while decreasing operation expenses. Why is microwave packet radio the right answer to backhaul wireless broadband services? Microwave packet radio transports voice as effectively as or better than leased T1 lines. The average leased line availability in the US is 99.9 per cent4. Most microwave links are designed to deliver 99.9995 per cent availability. Major US mobile operators recognize this advantage and the need to prepare for 4G service and have launched programmes to replace leased lines with microwave. The results have exceeded expectations and further strengthened the proposition that microwave transport is preparing mobile operators for a seamless transition into the future. Microwave packet radio meets the revenue/traffic model of wireless broadband services. Next-generation microwave packet radio has four important characteristics that address key backhaul requirements: 1. Multi-Service Aggregation – aggregates and carries any type of traffic – 2G, 3G or IP/Ethernet – over a common packet layer. In this case, the radio capacity is designed for the actual bandwidth needs and not by the number of T1s connected; 2. Service Awareness – manages the packets according to the service transported. This enables overbooking of low priority traffic with any technology – TDM, ATM or Ethernet; 3. Packet Node – enables the microwave packet radio to connect multiple directions with virtually no switching constraints. This is particularly suitable for dense LTE cell site deployments; and 4. Service driven adaptive modulation – can deliver three times more bandwidth over the same radio channel, thus keeping overall spectrum costs to pre-LTE levels. Up to 350 megabits of uplink traffic can be delivered, far above LTE cell site bandwidth requirements. How will US microwave backhaul networks grow? Since microwave is needed to meet 3G and 4G challenges, how can the US telecom industry move forward and increase its expertise in the effective design, deployment and maintenance of microwave networks? While the US enterprise segment and the rest of the world have already chosen ‘self build’ microwave networks for 60 per cent of their sites, what can the US mobile telecom industry do? Three options are open: 1. Many mobile operators are already using microwave networks. A natural option will be to expand and build larger microwave networks in order to respond to the challenges of mobile broadband services. As stated earlier, leased line replacement programmes have been active within the US for many years and it is expected that the volume of these initiatives will increase over the next several years; 2. Alternate access vendors (AAV) have emerged to provide backhaul services. They have experienced limited success since traffic and capacity requirements have remained low, so it can still be served by leased T1 lines. As the appetite for bandwidth increases, the need for new cost effective microwave solutions will become evident; and 3. Faced with the prospect of losing the revenues generated by their copper-based fixed assets, fixed-line operators will invest to ensure the revenue stream provided by mobile operators continues. To offer Ethernet services, the investment could be for equipment that provides Ethernet over copper, increasing the network’s fibre capacity or by building their own microwave networks. As 3G networks expand and 4G networks become a reality, migration to next generation backhaul networks will be inevitable. The only question is who will first take advantage of microwave, together with fibre, to beat the competition and build revenue.

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