Mobile Backhaul: Strengthening Backhaul

There is an excellent cellular technology around and devices to access those technological benefits, consumers are eagerly awaiting a great experience but these things gain momentum only if network infrastructure ensures a smooth flow of air waves over the network, that is where mobile backhaul plays a pivotal role and enhances the quality.

Quality of service/experience of mobile NGN technologies, broadband services such as mobile TV, mobile video is directly proportional to an efficient mobile backhaul networks. Let us consider a few prominent components of mobile backhauling and how operators could transform their networks in order to deliver high-end applications and increased bandwidth over a cost effective, less complex, and more reliable network.

Upgradation-Inevitable

Today's world of communication is all about mobility. We have reached a second phase of this mobility, ie, the 'data' transmission, the first phase being 'voice' market. During the first phase of mobile communications networks had been built for voice flow but of late, there is a quick transition to data transmission; hence the need of the hour is to strengthen mobile backhaul networks to deliver third and fourth generation services. Upgradation is a must also because of the complexity on networks due to increasing subscriber base, variations in type of traffic transported across network, and the demand for quality of service.

According to a recent report by Juniper Research, mobile operators globally will have to shell out nearly $840 bn over the next 5 years to upgrade backhaul networks to address data deluge. The report stressed that when existing backhaul infrastructure is incapable of supporting growth in consumption, radio network upgrades are not enough and it has to be augmented and operators ought to simultaneously manage the upgrade of their backhaul networks. The report said that in India alone, microwave would account for 87% of capacity in 5 years.

Voice-centric services were transmitted on a network built on traditional T1 circuit switching or by using TDM transport platform, but now there is a critical need to migrate the mobile backhaul network to technologies that can support quality of service and experience to separate traffic streams, timing synchronization, lower packet loss, and high availability. Backhauls ought to evolve from TDM to packet networks. Wireless networks have basically relied on TDM transport services for interconnection between cell sites and base station controllers (BSC) and mobile switching centers (MSC). The addition of 2.5G and 3G data services will increase the need for more bandwidth to cell sites, but the requirements are still relatively modest.

Upgrading to advanced backhaul technologies guarantees bandwidth constraints and enhances spectral efficiency of the wireless interface. Unlike TDM based transport technologies, upgrading to Ethernet enables operators to leverage on statistical multiplexing. This feature is important in aggregation backhaul applications, facilitating the optimization of traffic management over the network, reducing congestion, and helping operators get maximum benefits out of their networking investment.

Backhaul Savior—IP Based Networks

Second generation technologies (2G/2.5G) were designed for voice services but they are not efficient for data and video services. The radio access network for 2G/2.5G were channelized by TDM, and supported by PDH/SDH. At present the immediate plan of action of operators is to migrate its networks to Ethernet/IP/MPLS to leverage on 3G and 4G services because data-centric services are based on packet technology.

“IP based networks, which works on packet transport platforms, have the capability to transport different traffic types including circuit based voice, 2G, 3G based voice, and data over a common IP or MPLS based infrastructure alongside it will guarantee QoS and security requirements,” says Nagaraja Upadhya, VP, marketing & R&D, network product line, Huawei India. Besides, it offers lower latency, it reduces the total volume of equipment that is used when equipment has integrated capability of BTS, RNC, mobile core or all 3 and it is a very cost-effective solution. It is also easy to use and manage, it supports various services and maintains performance.

An added and the most prominent advantage of IP/Carrier Ethernet is that there are hardly any migration issues, it ensures co-existence of legacy technologies such as TDM/ATM and it addresses new deployments. It addresses migration and co-existence of legacy technological challenges by using pseudo-wires and circuit emulation.

Purely IP/Ethernet based greenfield deployment can deliver CoS, MPLS transport, and VPN services. “To strengthen mobile backhaul networks, operators should shift to IP and introduce carrier grade Ethernet functionality in layers 2 and 3, including supporting synchronization over Ethernet networks such as SyncE and 1588v2,” says Aviv Ronai, senior business development manager, infrastructure and networking group, Broadcom.

Backhaul Efficiency

According to Sanjay Nayak, chief executive officer, Tejas Networks, “Efficiency of a backhaul network can be measured in multiple ways. First is in terms of capex, ie, the capital spent and the bandwidth added. Second is in terms of operational expenses. This can include maintenance and troubleshooting costs, cost of maintenance personnel and power consumption.” He adds, “Tejas addresses all of these issues. Capex optimization happens due to flexible and modular architecture of these products which offer a pay as you grow model. The service provider only buys current capacity and can add more modules to the system as demand for bandwidth increases. The opex optimizations come from using state-of-the-art components and designs for products which lower power consumption and offer better reliability. In addition several mechanisms are built into these products to aid troubleshooting and even to predict faults based on performance data.”

An understanding of the wireless 2G/3G standards, cell site capacity requirements, and performance metrics (latency, jitter, availability) are of prime importance. Then the right technology, network, and architecture could be successfully implemented.

Network planners would have to draw the line of evolution between current and future. Because this line takes mobile operators from all TDM world to an all-packet one, ie, from low capacity to high capacity and 'from link by link' planning to a much broader network concept. Relying on fiber deployments is also a viable and better option due to time and cost issues and also because of limitations of copper in terms of capacity and distance.

Efficient backhauling has to address migration issues. Operators should opt for a risk-free migration path without abandoning revenue generating services, future capacity, and overall cost. Any migration process includes a large number of elements and holds many associated uncertainties; it is important to maintain support for existing transport networks while gradually transitioning the bulk of communication on to the next generation of backhaul network.

Industry stalwarts have put together 3 common migration strategies-carrying both Ethernet and TI/E1 traffic over NG-SDH/SONET where there would be no major change, carrying both Ethernet and T1/E1 traffic over packet switched networks which would be an ultimate change, and carrying native Ethernet and native T1/E1 traffic simultaneously over the same network without using any type of encapsulation, it would result in gradual change.

“The key components for an efficient and scalable backhaul network include supporting carrier grade Ethernet, enabling capacity growth, advanced spectrum utilization solutions (modulation, XPIC, wide channels, channel bonding), high radio performance to enable network savings (ie, antenna size), low latency, low power consumption, and power management,” says Aviv Ronai.

A Few Solutions

Tejas Networks offers 3 kinds of backhaul solutions each suitable for specific customer requirements-firstly for 2G expansion, where the mobile operator predominantly carries 2G voice traffic, who is looking to expand it and also offer a reasonable amount of 3G services. For such operators it offers Tejas MSPP solutions for microwave backhaul, which leverage existing investments and are optimized for voice traffic. Secondly, the solution for operators who have 2G traffic but are looking to expand into 3G and LTE services in a big way. For these operators, balancing their 2G voice revenues with the new data services is extremely important.

Tejas POTP solutions efficiently addresses this need to face the dilemma of how much voice and how much data capacity to deploy. Thirdly, the solution for operators who do not have any legacy voice traffic is Tejas pure packet solutions. These are primarily BWA licensees, looking to roll out greenfield networks and offer only data services. Tejas pure packet solutions for these operators provide optimized data services with support for advanced carrier Ethernet features like MPLS-TP, OAM, synchronization, circuit emulation, etc.

Broadcom's microwave backhaul SoCs provide enhanced performances and advanced capabilities together with high level of silicon integration which minimize physical footprint and reduce power consumption of microwave backhaul systems. SoCs for microwave backhaul enable higher capacities necessary for the constantly increasing mobile traffic, as well as networking functionalities needed for packet transport networks.

The NEC's iPASOLINK supports the transition from today's hybrid TDM and Ethernet backhaul towards full IP transport, while significantly reducing the cost of ownership thanks to its all-in-one converged design. iPASOLINK's flexible modular architecture allows operators to optimize their network strategies and to gradually invest in step with actual service and traffic demands. This design, combined with NEC's unparalleled engineering reliability, ensures that iPASOLINK delivers outstanding value to operators.

Operators are keen on IP transition and they are gradually transforming the networks to support next-generation mobile technologies. In October 2011, Tata Teleservices (TTSL) has signed a strategic agreement with NEC Corporation to deploy iPASOLINK platform. This platform enables TTSL to transform its backhaul mobile transport network that can be adapted for next-generation IP based networks.

It offers ultra flexibility and meets the requirements of current capacity and service demands of customers. “NEC Corporation is one of our key suppliers of microwave equipment, having a total installed base of more than 100,000 terminals. NEC has been associated with TTL for many years, providing microwave equipment and services for our CDMA and GSM network rollouts. TTL is now in the process of expanding its network for both coverage and capacity in the mobility and enterprise business segments, which will require backhaul of both TDM and IP traffic. Our requirements, therefore, necessitate the deployment of hybrid radio in the network.

With regard to choking in the network, a well designed and efficiently maintained network resolves the issue. Bypassing robust technologies like IP or OTNb at the design level and will removing the choke points in the network and enhances quality of service and experience. The network should be equipped by deep packet inspection technology. Huawei offers 'single platform backhaul network', an apt backhauling solution amongst other solutions, it supports multiple technologies like 2G, 3G and 4G. It can support different infrastructure as well like microwave and fiber, says Nagaraja Upadhya.

NEC's iPASOLINK platform fully meets these requirements and can be adapted for next-generation IP based networks,” says AG Rao, executive president, enterprise business and technology, TTSL in a recently released statement. Takayuki Morita, senior VP of NEC adds, “As the Indian mobile communication market continues its rapid expansion, operators face the challenge of making significant investments in order to provide next generation mobile broadband services while managing capex and opex. This agreement between TTSL and NEC proves that mobile operators have the appetite for a single, converged and flexible backhaul platform that they can manage and adapt according to their network service demands.”

As mobile operators are facing several challenges while shifting to triple play and 3G/4G, they need much more bandwidth but at a much lower cost per bit. The vast array of backhaul technologies should ensure that the old and new technologies work seamlessly and economical together. The expectations from backhauling ecosystem include lower backhaul costs for mobile operators, higher revenues for mobile transport operators and the assurance of increased profitability for both.