WHITE PAPER ® FlexPort µWave A Better Approach to High-Capacity Microwave Backhaul Page 1 of 11 WHITE PAPER The explosive need for capacity The need for backhaul capacity in mobile networks is exploding. The increasing presence of smart phones and the expectation of users that these phones provide the same experience as a desktop computer is the major driving force behind the proliferation of mobile data traffic. These devices are performing more and more functions and have features that require huge amounts of bandwidth. December 2009 marks the first time that data traffic exceeded voice generated calls. In a keynote speech at the Monaco Media Forum 2010, Ericsson President and CEO Hans Vestberg estimated that by 2020 there will be 50 billion connected devices! According to the Cisco Visual Networking Index Global Mobile Data Forecast, 2009-2014, by 2014 mobile traffic will have increased 39 times over 2009 levels while almost 66% of the mobile traffic will be video. The evolution from 2G/3G mobile networks to 4G creates challenges for operators that go well beyond the adoption of new handset air-interface technologies. 4G Long Term Evolution (LTE) and WiMAX capacity translate into aggregate base station capacities that grow from the tens of megabits per second common today to the hundreds. This in turn places demands on backhaul networks that drive a transition from copper and low-capacity microwave links to fiber and new gigabit wireless backhaul solutions. This growth in capacity is primarily driven by data services; therefore, operators also look to transition from circuits to packet-based architectures in order to more efficiently adapt to the new data-centric world. In order to realize the efficiency gains promised by packet architectures, robust traffic and network management tools are required to optimally address a high mix of application traffic with widely varying Quality of Service (QoS) requirements. While operators look towards a new data-driven future, incumbent operators will still rely on their legacy of 2G/3G networks for years to come. Backhaul solutions that look forward to 4G must also support existing access technologies, without imposing substantial costs or complexities on operators. Removing backhaul as a network performance bottleneck means that network subscribers will experience the full potential of 4G access solutions – and that network operators can grow their 4G site capacity over time, without having to re-engineer their backhaul infrastructure. Traditional Microwave vs. the FlexPort ® Platform This white paper will discuss how traditional microwave radios have coped with squeezing extra bandwidth from their platforms. There are several methods that have been employed over the years to accomplish this. These technologies have produced varied degrees of success, and their respective advantages and limitations are discussed accordingly. An innovative and more efficient technology is proposed with the FlexPort ® platform. The FlexPort µWave provides an innovative, multi-channel solution that dramatically increases the capacity of the radio with no additional hardware costs. This white paper will outline these comparisons in detail. Page 2 of 11 WHITE PAPER Traditional methods of squeezing more capacity out of a microwave link Typical microwave radio solutions in the 6 to 38 GHz range are limited to capacities of around 350 Mbps per RF channel, due to narrow spectrum allocations, the use of high order modulation, and narrow channel bandwidth limits. The only way to reach gigabit capacities using these links is to multiply the number of radio transceivers and in turn increase the hardware costs of the link. These traditional methods of providing “gigabit” speeds by utilizing microwave frequency solutions are inefficient in their implementation, yield less than true gigabit throughput, and yield higher CAPEX costs for the user. Radio systems that are designed to start off at initial capacities of 10 ~ 50 Mbps data rates and have the capability of expanding to 350 Mbps via a software upgrade are simply not designed for high capacity full-rate gigabit transport. As such, to achieve higher capacities, manufacturers must cope with taking these lower capacity solutions and doubling the hardware and/or adding intricate interference cancellation (XPIC) or compression technologies to achieve near gigabit speeds. Split-Mount Architecture Split-mount architecture is among the most popular microwave designs worldwide. This type of architecture involves the use of indoor and outdoor hardware typically called Indoor Units (IDU) and Outdoor Units (ODU) and an interconnecting coaxial cable (IFL). This design has several advantages of flexibility and convenience in allowing the operator to easily access a variety of TDM and IP connections from inside the building or equipment cabinet. The evolution of split mount design saw the IDU morph from a full rack space unit capable of generating a single data transmission to multiple plug-in cards supporting multiple carriers emanating from the same box. However, the limitation has always been in the outdoor component of the radio and multiple outdoor units are needed to support the multiple carriers from the IDU to achieve near gigabit speeds. The initial costs of a 350 Mbps circuit are relatively low, which allows the operator to start off his or her back-haul link with a low CAPEX; however, the subsequent costs to upgrade the link to a “gigabit” speed scales linearly. This translates into doubling hardware costs to achieve less than true GigE speed. Page 3 of 11 WHITE PAPER Typical Split-Mount Microwave Configuration While split-mount architecture remains a popular design, it is not optimal for full-rate gigabit transport. The disadvantages of split-mount architecture for gigabit speeds are the added cost of an additional IDU and the expensive rack space needed to house it, as well as the added installation time. Certain microwave solutions allow the user to have the ability to insert a plug-in module into an IDU chassis while other solutions require a second IDU to be installed in the rack in order to add a second 350 Mbps data link. In either of these cases a second IFL cable must be pulled to the ODU, adding additional labor costs to increase capacity over the link. ODU Combiner An ODU combiner is commonly used to attach two microwave radio ODUs to a single antenna. Combiners are an effective way to aggregate multiple ODUs onto one antenna, providing lower tower / roof rental fees. However, with this design, link performance is degraded due to the losses associated with splitting and combining RF signals to/from a single antenna port. The ODU combiner adds additional losses to the system and from a CAPEX perspective increases the hardware costs. With the addition of an ODU combiner in the system, the link budget calculations will change. When upgrading the link beyond 350 Mbps and installing a second ODU and combiner, the link budget is degraded and it may be necessary to increase the antenna size on one or both ends of the link to compensate for the losses incurred by using the ODU coupler. Page 4 of 11 WHITE PAPER In cases where the operator starts off with 350 Mbps capacity (utilizing one set of radios), the addition of an ODU combiner is used in conjunction with the extra hardware needed to achieve higher capacity. This always results in an expensive tower climb to install the second ODU, the ODU combiner, and the second IFL cable. While an ODU combiner is used to aggregate two ODUs onto a single antenna, it is not the most favorable solution for providing true gigabit rates over the link. ODU combiners add costs to the overall solution, and the operator must account for the additional losses in the system in their link budget calculations. In addition, the ODU combiner, along with the second ODU, adds additional weight to the tower and, importantly, adds a second tower climb to upgrade the capacity of the link. XPIC Cross Polarization Interference Cancellation or XPIC allows the assignment of the same frequency to both the vertical and horizontal polarization on a microwave path. XPIC is used in situations where available frequencies are limited and it may be possible to assign the same frequency twice on the same path using both polarizations. With XPIC the solution requires more expensive dual-polarity antennas with very high cross polarization discrimination. The use of XPIC does not decrease the need for additional IDUs and/or ODUs to transmit multiple IF channels for near-gigabit speeds. In addition, the link availability calculations are degraded as the link will perform no better than the worst of the vertically or horizontally polarized signals. In most cases, at the upper microwave frequencies, the use of horizontal polarization causes lower link availability than do links utilizing vertical polarity. ODU #1 ODU #3 Vertically Polarized Signals ODU Combiner ODU Combiner or OMT or OMT Horizontally Polarized Signals ODU #2 ODU #4 XPIC Operation – Simultaneous Vertical and Horizontal Transmission Paths Page 5 of 11 WHITE PAPER Introducing the FlexPort µWave The FlexPort family of high capacity millimeter wave and microwave radios offers carriers, service providers, and government and enterprise users the ultimate flexibility in an access and aggregation backhaul solution for today’s networks. The FlexPort18 and FlexPort23 microwave radio systems have been designed specifically to meet the requirements of operators, carriers, and service providers requiring full-rate gigabit connectivity in a single, compact, all-outdoor enclosure. FlexPort18 and FlexPort23 accomplish this through an innovative approach by offering multiple RF channels without the need for additional hardware, as with other licensed frequency band products. This helps ease installation and maintenance costs on the network by offering only one device to install and manage, thus providing the user with a highly reliable, fully integrated backhaul solution.