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Wireless backhaul in the 5G era

8 Feb

Facing challenges wireless backhaul as the mobile industry evolves towards 5G

The future of mobile technology is gaining steady momentum with “5G” targeted for early commercial deployment by 2020. This major infrastructure overhaul is yet to be fully realized with regards to access technology, however it is clear the services to be offered in 5G networks will pose many challenges and constraints on underlying networks layers, such as wireless transport infrastructure.

Here we’ll describe these challenges and the new technologies and concepts that will allow wireless transmission to satisfy 5G requirements in the 2020’s

5G – the known and the unknown

Many of the building blocks of 5G-technology architecture are not yet known or well defined. Access frequency, for example, is forecasted to migrate from the decimeter-wave realm (sub-3 GHz) to the centimeter-wave and millimeter-wave domains (3 GHz to 300 GHz) in order to satisfy the incredible growth in capacity demand. Yet, the standardization of operating frequencies, as well as other technological and architectural specifications are far from complete. The move to 5G will pose specific and well-defined challenges to network infrastructure.

Such 5G-unique challenges are:

More capacity per device: One of the main goals of 5G services is to provide ultra-high capacity per end device, which means operators are going to need to add more spectrum, improve spectrum efficiency or roll out more infrastructure.

More devices: The exponential growth in the number of “standard” devices (i.e. smartphones, tablets, computers, smart home devices, wearables, etc.) is expected to continue and the average number of devices per person is expected to increase.

New types of devices The mass introduction of “Internet of Things” and machine-to-machine services will create a large increase in the number of connected devices, adding non human-controlled devices to the mix and resulting, as forecasted by GSMA, in an exponential increase in the total number of connected devices

New services: The massive increase in infrastructure capabilities will likely enable new services. Services such as augmented reality, tactile Internet, mobile “anything-as-a-service” and virtual reality will enrich the service offering, provided both by mobile operators and over-the-top service providers.

While the trends and services mentioned above explain the major benefits of 5G, these benefits will require some major changes in the way mobile networks are built, posing significant burdens on the underlying infrastructure – and in particular, the wireless backhaul/transport layer.

Higher capacity density

Multiplying the increase in the capacity per device with the growth in the number of mobile devices served by the network results in a huge increase in capacity density (the required capacity per a given area). This can result in an increase of up to 1,000-times the current capacity density in “4G” networks.

However, since a site capacity increase of 1,000-times is not feasible, and since the forecasted move to higher radio access network frequencies will also require smaller coverage areas per cell site – the mobile grid will become much denser than it is today. This will incorporate the addition of macro cells as well as small cells on poles, towers and rooftops, in addition to mass deployment at the street level, utilizing street furniture and light poles as part of the physical infrastructure.

These changes will challenge the wireless transport network with the following:

· Higher capacity wireless backhaul links per cell site. While current wireless backhaul links serve requirements of hundreds of megabits per second, future links will be required to support dozens of gigabits per second.
· Denser wireless backhaul links, due to denser cell site grids, will require a better utilization of wireless backhaul spectrum, as frequency reuse will be highly limited as links get closer to each other.
· Mass deployment of street level sites will require high capacity non-line-of-sight wireless backhaul links, as well as quickly installed, low-footprint, low-power consumption equipment.

Service and network virtualization

The need to improve operational efficiency, as well to dramatically shorten time-to-market for new, revenue generating services together with the rare opportunity of a forklift change in network infrastructure, will drive mobile operators to massive virtualization of their networks and services. From cloud-based services, through software-defined networking and network functions virtualization infrastructure and even virtualized RAN (cloud RAN), networks will become heavily software driven, requiring the wireless transport infrastructure to seamlessly integrate into the SDN/NFV architecture. This will enable multidomain, multivendor network resource optimization applications as well as faster time-to-market for new services. Cloud RAN will also require cloud backhaul (wireless front haul) to enable RAN resource effective optimization.

Redefining wireless transmission

While wireless backhaul will maintain, if not build upon its position as the most flexible and cost-effective backhaul technology for mobile networks in the 5G era, in order to do so, the technology will need to undergo a major evolution.

– High-capacity wireless backhaul will enable mobile operators to keep-up with capacity demands, and maintain excellent quality of experience for their customers while meeting operational efficiency targets by saving spectrum costs and avoiding costly and time-consuming fiber deployment. Traditional microwave bands (4 to 42 GHz) will leverage wider channel spacing (such as 112 megahertz and 224 megahertz), higher modulations schemes (4096 QAM and up) as well as ultra-high spectral-efficiency techniques such as line-of-sight multiple-input/multiple-output to enable up to 10 Gbps of long- and medium-distance connectivity.

– Short-distance connectivity will heavily utilize higher-frequency connectivity, while E-band and V-band solutions will benefit from additional capacity boosting techniques (currently more common in microwave solutions). This will include XPIC, LoS, MIMO and higher-modulation schemes, enabling rates of more than 20 Gbps per link. As millimeter-wave spectrum will be heavily used for 5G RAN, additional, higher frequency ranges will likely be allocated for wireless transmission. Above 100 GHz, bands such as W-band and D-band, though not yet regulated, are already undergoing initial research and development efforts in order to create power efficient, small form-factor, ultra-high capacity wireless transmission solutions.

– Increasing re-use of wireless backhaul spectrum will also enable operators to meet their operational efficiency targets by saving spectrum fees, as well as increasing the subscribers’ quality of experience by locating their cell site at the optimal location without the constraints posed by wireless backhaul frequency allocation and planning.

– High-capacity NLoS point-to-point wireless transmission solutions will be able to enable true street-level mass deployment to accommodate capacity and coverage requirements in 5G dense-urban deployments. While current, sub-6 GHz, provide a fair solution for 4G street-level deployments backhaul, 5G deployments will require capacities far beyond the scope of such solutions and will call for high capacity, microwave and millimeter-wave NLoS solutions.

– Microwave NLoS, as we already know, is theoretically feasible and has successfully been implemented in several occasions, however, in order to make it commercially efficient, microwave and millimeter-wave NLoS implementations will need to undergo an additional evolution that would incorporate adaptive channel estimation in order to ensure capacity and availability of such solutions. Moreover, a combination of NLoS adaptive channel estimation with MIMO implementation will need to be used, in many cases, as it increases link robustness, which is required in a NLOS environment.

On top of NLoS operation mode, street-level backhaul will also feature low footprint, low-power consumption, zero-touch provisioning and enhanced security.

Virtualized wireless backhaul

Network virtualization enables operators to increase their operational efficiency by making their infrastructure and resource utilization much more efficient. It also allows the very fast introduction of new services and technology.

Wireless backhaul integrates, via open interfaces, with the end-to-end SDN and NFV infrastructure and enables the SDN application to achieve network resource optimization (spectrum, power), higher service availability (with smart reroute mechanisms) and faster introduction of services and technologies. All of the above is applicable in the wireless transmission domain, as well as in multidomain, multivendor environments (assuming vendor alignment to standard based interfaces and applications)


While 5G will bring many benefits to users as well as mobile operators, in order to make it a reality, several challenges must be overcome. Challenges derived from higher capacity requirements, denser cell-site grids, street-level deployments, network virtualization and mission critical applications will drive wireless transmission into a new era, incorporating new frequency bands, capacity boosting techniques, NLoS operation and virtualization enabling operators to increase their operational efficiency, provide higher quality of experience to the subscribers and faster time to market for new services and technologies.



Mobile backhaul performance and the challenge of 5G, convergent technologies

25 Jan

InfoVista looks at mobile backhaul performance challenges

Mobile backhaul is already a massive challenge for mobile network operators today, as the demand for coverage and capacity that can handle data has exploded at a breakneck pace over the past several years. Assuring quality is only poised to become even more difficult with the onset of new convergent technologies and the brewing-storm that is widespread “5G” adoption on the horizon.

Mobile traffic trends

According to the June 2015 Ericsson Mobility Traffic Report, LTE mobile subscribers will show a growth of 40% compound annual growth rate from 2014 to 2020. It’s expected 3G networks will still be the dominant access technology by 2020 – and 2G will still be common in many developing regions – but new connectivity networks will also be coming online in the next few years that will put greater pressure on the already pressed global market.

The gap between traffic and revenue

The problem with this proliferation of data usage in relation to backhaul is the financial pressures that are already weighing heavily upon network provider capabilities. Despite accounting for almost 85% of network usage, data accounts for only 40% of network revenue.

An even more startling picture of the gap between traffic capacity and revenue comes to light when considering from 2008 to 2013, data traffic grew 46-times over while revenue from data over the same period only saw a three-fold increase.

The fact LTE networks natively don’t carry voice traffic is a contributing factor to the challenges network operators face when dealing with this traffic explosion. Providers need to find a way to share investments being made into LTE backhaul with voice (circuit-switched) services, while making sure this reallocation can still assure quality of service in a convergent scenario.

The real test for network providers is going to come with the arrival of 5G. The challenge stems from the fact not only will more customers the world over demand data-centric plans, but the bandwidth needs are on track to balloon well beyond current network capabilities. Research has indicated peak bandwidth per device may reach up to 1 gigabit per second on average, which is much greater magnitude than what LTE networks can deliver today.

If that was not enough, new 5G use cases such as “tactile Internet” will require extreme real-time communications, demanding backhaul networks deliver end-to-end latency as low as 5 milliseconds, which is an order of magnitude less than what the best LTE networks can deliver today.

What it means for tomorrow’s backhaul networks

It’s not as if existing “legacy” networks can be simply replaced or deactivated. In fact, mobile operators face a scenario where network complexity will only increase in the long run, as next-generation LTE and 5G access networks are coming down the pipeline. That, in turn, means legacy networks will co-exist with new technologies for the foreseeable future, adding yet another dimension to network operations that engineering teams need to handle when operating and assuring the quality of the network.

In fact, because of all these factors combined, mobile backhaul operations are becoming larger and less predictable to manage with traditional tools. In the past, 2G networks were predominantly voice-oriented and deployed on top of traditional, extremely reliable TDM/SDH backhauls. In 3G, we often see hybrid deployments where TDM/SDH co-exist with IP/MPLS, ATM and even Ethernet-based backhauls.

The arrival of LTE, LTE-Advanced and newer technologies such as voice over LTE heralded some more drastic changes to the way operators approached backhaul. Many mobile operators decided to migrate the entire backhaul to fully convergent technologies such as IP/MPLS and carrier Ethernet, effectively transporting all voice and data traffic on top of packet-switched networks.

With a larger and less predictable backhaul to manage, “up” or “down” indicators became evidently insufficient. The very fact different backhaul domains (access, aggregation, metro) and even different backhaul network layers could greatly affect each other’s performance – as well as the overall quality of service parameters – meant monitoring and troubleshooting the mobile backhaul with multiple disconnected tools became impractical.

The perspective: if the mobile backhaul already looks complex today – being composed of a litany of vendors, technologies and topologies – it will become even more complex, with both real and virtual networks devices poised to coexist in 5G software-defined networking and network functions virtualization native architectures – not to mention new network architectures will need to co-exist with the legacy for a long time. After all, subscribers by 2020 will still rely on 2G and 3G to access for both data and voice services.

How to deliver on future mobile backhaul expectations

From whatever angle you look at it, mobile backhaul is becoming larger and more complex to manage in the coming years. Yet, as daunting as this forecast for the next few years may seem for mobile operators, there are tools available that will help mobile operators support this increasing complexity while maintaining exceptional QoS.

Real-time, multi-layer troubleshooting – the ability to monitor all layers of the mobile backhaul in real-time – will play a key role in managing voice and data quality of experience in the new mobile landscape, reducing time to repair and increasing network uptime.

Providers will also need to rely on automated network topology discovery. A modern performance management tool must automatically handle these changes, so that the network operations center and software operations center can actually focus on monitoring the network, rather than expending time and energy manually cross checking and correcting grouped KPIs.

Equally important is to have end-to-end cross-domain visibility, where operation teams can see the performance of the radio access network, backhaul and core in one single plane of glass. This is also important to enable different teams (ex: RAN and transport) to work together and accelerate the time to resolution of these more complex cross-domain scenarios.

And with network capacity expectations on pace to boom, providers need to always be ahead of the game and have a plan for future fluxes in capacity. A performance management tool will need to monitor traffic KPIs evolutions and trends, extrapolate historical data and act proactively to adjust (right-size) backhaul links as they see fit.

Ultimately, a unified performance management tool can help operators increase the quality of experience of mobile subscribers, resulting in less churn and revenue protection. It also brings a series of other capital expense and operating expense gains, with a reduction in the number of tools and their associated costs.

In fact, these business benefits can be quantified and measured, and past experience has shown even more complex performance assurance consolidation projects can pay for themselves (return on investment) in 12 to 24 months (depending on the case).


Some mobile operators are reluctant to make the investment, in part thinking traditional assurance practices and tools they have used up until today can handle the job. But as we discussed, the network size and complexity, as well its statistical behavior, will demand the adoption of modern unified performance management tools.

If that was not enough, there are clear business benefits in doing so, resulting in a clear ROI for the investment. Even for those mobile operators with capex restrictions, there are windows of opportunity to make this necessary move, especially in view of new cloud-based performance management solutions that allow operators to switch to an opex-based model and expedite the ROI even further.

Those mobile operators that act decisively will prosper; those that hesitate are likely to find themselves playing catch up.

Editor’s Note: In an attempt to broaden our interaction with our readers we have created this Reader Forum for those with something meaningful to say to the wireless industry. We want to keep this as open as possible, but we maintain some editorial control to keep it free of commercials or attacks. 


5G Wireless Backhaul Networks: Challenges and Research Advances

6 Feb

5G Wireless Backhaul Networks:
Challenges and Research Advances by
Xiaohu Ge, Hui Cheng, Mohsen Guizani, and Tao Han
This paper was published on IEEE Network • November/December 2014

Lets see some abstract section of this paper:
5G networks are expected to achieve gigabit-level throughput in future cellular networks.
However, it is a great challenge to treat 5G wireless backhaul traffic in an
effective way. In this article, we analyze the wireless backhaul traffic in two typical
network architectures adopting small cell and millimeter wave communication technologies.
Furthermore, the energy efficiency of wireless backhaul networks is compared
for different network architectures and frequency bands. Numerical
comparison results provide some guidelines for deploying future 5G wireless backhaul
networks in economical and highly energy-efficient ways.

So lets download this full paper:
Download Link : 5GBACKHAUL


The Mobile Backhaul Evolution

2 Oct

As mobile data usage proliferates, so does the demand for capacity and coverage, particularly with the rise of connected devices, data-hungry mobile apps, video streaming, LTE roll-outs and the popularity of the smartphone and other smart devices. With mobile data traffic expected to double annually, existing mobile backhaul networks are being asked to handle more data than they were ever designed to cope with, and operators are being asked to deal with a level of capacity demand far greater than ever could have been imagined.

Breaking the backhaul bottleneck
The demand on operators to provide more, and faster, services for the same costs is putting mobile backhaul networks under intense pressure, and effectively means the operator ARPU (Average Revenue per User) is in decline. iGR Research Company has confirmed that the demand on mobile backhaul networks in the US market will increase 9.7 times between 2011 and 2016, fueled by rapidly growing data consumption, faster than operators can keep up with. Surging data traffic is stressing existing connections and forcing many operators to invest in their network infrastructures in order to remain competitive and minimize subscriber churn.

Mobile operators realize that in order to meet capacity, coverage and performance demands, while raising their ARPU, they need to evolve their mobile backhaul networks to perform better and be more efficient. As the capacity and coverage demands accumulate, mobile backhaul evolution comes to the forefront as an area that operators must address and align with growing demand.

Evolution not revolution
As wireless technologies have developed over the years, a mixture of transmission technologies and interfaces to Radio Access Network (RAN) equipment have been utilized to support communications back to the mobile network operator, including 2G, 3G and now 4G LTE. Today, operators evolve their backhaul by converging multiple backhaul technologies into one unified technology and converging multiple parallel backhaul networks into a single all-IP network. Based on IP and MPLS, having one, all-IP network makes more efficient use of network resources, reduces operational costs, and is cheaper to manage and maintain. IP gives operators the ability to converge RAN traffic and MPLS technology addresses the challenge of

Source: A Knowledge Network Article by the Broadband Forum

How to manage the LTE revolution in Asia-Pacific with next generation backhaul

2 Oct

LTE growth is being driven by consumer demand for data, the absence of fixed line infrastructure in many parts of emerging APAC (EMAP), and the need to provide the network capacity to enable next-generation mobile and services.

Operators are desperately looking to efficiently scale network capacity; wireless technology holds the key to delivering the performance and profits operators require as the mobile landscape changes dramatically.

Full Article

Consumers all over the world want the fastest network, with the highest quality of experience. This is no more evident than in the Asia-Pacific (APAC) region where LTE is now out of the experimental stage and being deployed widely across most of the developed markets in the region. According to a new report by Allied Market Research, APAC is forecast to surpass other geographical markets by 2020 with approximately 40 per cent of the global LTE market. Analysys Mason is also forecasting that APAC and Latin America will account for the majority of the networks that are planned for launch by 2018. A recent report from the Global Mobile Suppliers Association confirms the demand for LTE networks, estimating an approximate 200 million LTE subscribers globally with the APAC region boasting 77.8 million, a 38.8 per cent share of the overall subscribers.

LTE growth drivers

LTE growth is being driven by consumer demand for data, the absence of fixed line infrastructure in many parts of emerging APAC (EMAP), and the need to provide the network capacity to enable next-generation mobile and services. Rapid economic development, which has increased the region’s prosperity, has also been a factor in making mobile services more affordable and helped seed the LTE ambitions of operators.

In addition, access to high-speed LTE is facilitating a wide variety of socio-economic benefits across APAC, encouraging governments to incentivise operators to deploy next generation networks. LTE is helping people lead more productive lives and, for example, enabling businesses to become more efficient in delivering goods and services. The onset of widespread broadband connectivity across the region is sustaining this economic development with improved networks in some of the countries in the EMAP region, empowering education, increasing trade and driving innovation.

LTE diversity

Growth in LTE, and the subsequent rise in mobile data traffic, is leading to an increase in infrastructure investment. Operators have the challenge of efficiently scaling infrastructure which delivers the capacity to satisfy consumer appetite for mobile connectivity and support the array of new services being deployed across the region.

This challenge is evident in the diversity of development across APAC’s mobile market which has led to a multitude of LTE network adoption scenarios. The variety is evident in the 47 countries and 3.7 billon people in the region which contain many intricacies and complexities due to economic, political and geographic factors. South Asia, for instance, reflects a diverse mix of mobile and internet diffusion patterns. Malaysia and Singapore have a mature network infrastructure and mobile penetration exceeding 100 per cent, whilst countries like the Philippines and Indonesia are still considered to have a developing infrastructure.

It is expected that these EMAP regions will be able to take most advantage of the demand for LTE networks rather than the developed APAC (DVAP) regions that have more mature offerings. However, managing and constructing an LTE network has many factors to consider, not least the technical requirements needed for mobile backhaul. As always, the cost of backhaul is a paramount consideration in running and launching new networks.

The Philippines is a good example of the complexities of managing LTE networks. A recent report by OpenSignal Inc. has concluded that the Philippines have the slowest LTE connection among the 16 countries surveyed, with 5.3 Mbps (megabits per second). Operators in EMAP regions have increasing pressure to provide the capacity needed to handle the huge data demands from smartphones, tablets and new technologies such as M2M. Operators are in danger of failing to provide consumers and business with the fast, high quality network that is demanded of LTE.

Wireless innovation

Operators have known for some time that they need to drive innovation in their business processes and run networks at a much lower cost per bit to achieve success. However, the extensive capital expenditures (CAPEX) and operating expenditure (OPEX) challenge in setting up new infrastructure is seeing operators struggle to make a successful business case. For example, putting vast amounts of fibre networks into the ground can encounter huge costs and lengthy time to the market as well as a geopolitical minefield of regulation which can reduce an operator’s return on investment (ROI). Even worse, fibre can suffer from poor reliability and high maintenance costs due to either deliberate or accidental damage. Increasingly, operators are turning to a new wave of efficient, flexible and high capacity wireless technologies, including point-to-multipoint (PMP) microwave.

Traditionally, the low ARPU in the APAC countries puts even more emphasis on operators to make efficiencies. This means that, for the overall business case to work, every bit of data must be delivered at the lowest possible cost, and it’s this imperative that makes operators turn to innovative solutions like PMP microwave. Because the hub radio itself, as well as the backhaul spectrum, are shared across a number of LTE sites in the sector; both the hub equipment and spectrum cost are amortised across this number of links. Analyst consultancy Senza Fili recently found this allows PMP microwave to deliver savings of up to 50 per cent over other forms of backhaul, while delivering the same carrier-grade service essential for LTE.

PMP microwave uses area-licensed spectrum to create a sector of backhaul coverage from a single hub site and ensures the guaranteed quality of service LTE demands. Multiple cell sites can be backhauled within this sector, and bandwidth is dynamically shared across all links. Due to this real-time allocation of spectrum, PMP microwave enables the ‘troughs’ of one cell site’s traffic demands to be filled by the ‘peaks’ of another. This aggregation reduces the total bandwidth required for a sector and has been proven to improve spectral efficiency by at least 40 per cent when compared to traditional point-to-point (PTP) technology. By efficiently managing the backhaul spectrum required for LTE, operators can run networks at a much lower cost and achieve a higher ROI – crucial at a time where revenues are under threat. Importantly, PMP microwave (which operates above 6GHz) has the capacity to handle the most demanding LTE networks and is already proven in LTE backhaul deployments in other regions of the world.

Enterprise access

Whilst the enormous promise of LTE is clearly evident, operators still need to look at new and innovative ways to unlock the true potential of their backhaul infrastructure and increase ROI. Many operators see the deployment of multiple virtual networks over a common physical network as the answer. Some operators currently choose to build completely new LTE or enterprise access networks to sit alongside legacy infrastructure, however this can create inefficiencies across the different generations of technologies.

The latest backhaul technology now allows for new profitable business models to be created. By creating a converged backhaul network, LTE backhaul can be accommodated whilst also using the virtual networking capability to monetise spare capacity by deploying additional services to businesses. A converged PMP microwave backhaul network, for instance, enables operators to introduce fixed enterprise access services on the same LTE network – serving business with next generation connectivity.

This efficient use of backhaul and spectrum enables operators to invest in fast mobile speeds and carrier grade services, whilst allowing for competitive pricing and increasing profitability. This increase in ROI is particularly beneficial at a time where the fragmentation of spectrum is a particular issue for APAC.


The long term growth prospects for mobile broadband in APAC are enormous as operators are finding consumers and businesses hungry for transformational mobile and internet services. With operators desperately looking to efficiently scale network capacity, wireless technology holds the key to delivering the performance and profits operators require as the mobile landscape changes dramatically.

New business models and innovative wireless backhaul will not only protect investments in LTE but pave the way for new services and revenue opportunities – helping operators reduce churn in what is becoming an increasingly competitive market.

It is an exciting opportunity for operators in APAC to upgrade their technology for LTE and bring new innovative services to the market. With cost savings obtained by increased efficiency and utilisation of resources, quality of service or features need not be sacrificed with wireless technologies. As customer preferences change and mature in the APAC region, there is huge potential in the market to deploy efficient and flexible wireless technologies to build fast successful networks.


LTE Security: Backhaul to the Future

20 Feb

It’s hard to hit moving targets, but subscribers to 4G and LTE networks need to be assured that their data has better protection than just being part of a high volume, fast-moving flow of traffic. This is a key issue with LTE architectures – the connection between the cell site and the core network is not inherently secure.

Operators have previously not had to consider the need for secure backhaul.

2G and 3G services use TDM and ATM backhaul, which proved relatively safe against external attacks.  What’s more, 3rd Generation Partnership Project (3GPP) based 2G and 3G services provide inbuilt encryption from the subscriber’s handset to the radio network controller.  But in LTE networks, while traffic may be encrypted from the device to the cell site (eNB), the backhaul from the eNB to the IP core is unencrypted, leaving the traffic (and the backhaul network) vulnerable to attack and interception.

This security problem is compounded by the rapid, widespread deployment of microcell base stations that provide extra call and data capacity in public spaces, such as shopping centres and shared office complexes.  The analyst Heavy Reading expects that the global number of cellular sites will grow by around 50% by the end of 2015, to approximately 4 million.   Many of these new sites will be micro and small cells, driven by the demand to deliver extra bandwidth to subscribers at lower cost.

Microcell security matters

These small base stations placed in publicly-accessible areas typically only have a minimum of physical security when compared to a conventional base station.  This creates the risk of malicious parties tampering with small cell sites to exploit the all-IP LTE network environment, to probe for weaknesses from which to gain access to other nodes, and stage an attack on the mobile core network.  These attacks could involve access to end-user data traffic, denial-of-service on the mobile network, and more.

Furthermore, operators are starting to experience pressure to deliver strong security for subscribers’ data, because of competitive pressure from rivals and the need to assure both current and future customers that their mobile traffic is fully protected against interception and theft.

As a result, backhaul from the eNB to the mobile core and mobile management entity (MME) needs securing, to protect both unencrypted traffic and the operator’s core network.  Especially when the backhaul network is provided by a third party, is shared with another operator or provider, or uses an Internet connection – which are all common scenarios for MNOs looking to deploy backhaul with the lowest overall cost of deployment and ownership.  While these types of backhaul network deliver lower costs, they also reduce the overall trustworthiness of the network.  So how should MNOs protect backhaul infrastructure against security risks, to boost subscriber trust and protect data and revenues?

Tunnel vision

To mitigate the risks of attack on backhaul networks, and to protect the S1 interface between the eNB and mobile core, 3GPP recommends using IPsec to enable authentication and encryption of IP traffic, and firewalling at both eNB and on the operator’s mobile core.  The 3GPP-recommended model involves IPsec tunnels being initiated at the cell site, carrying both bearer and signalling traffic across the backhaul network and being decrypted in the core network by a security gateway.  IPsec is already used in femtocell, IWLAN (TTG) and UMA/GAN deployments, and a majority of infrastructure vendors support the use of IPsec tunnels in their eNB solutions.

However, while IPsec is the standard approach to security recommended by 3GPP, there are common concerns about its deployment, based on factors such as the operator’s market position and customer profile;  the cost and complexities of deployment; and how IPsec deployment might impact on overall network performance.

MNOs need to be confident that their IPsec deployments are highly scalable, and offer high availability to cater for the expected explosive growth in LTE traffic and bandwidth demands.  This in turn means using security solutions that offer true carrier-grade throughput capabilities as well as compliance with latest 3GPP security standards, while being flexible enough to adapt to the operator’s needs as they evolve.  At the same time, the IPsec solution should be as cost-effective as possible, to minimise impact on budgets.

Scalable security

To address these concerns, the IPsec security solution should run on commercial off-the-shelf platforms embedded in virtualized hypervisors.  This avoids the costs and complexity of having to aggregate backhaul traffic to a central network point, or complementing existing solutions with additional hardware, while also enabling rapid deployment and easier management.  A virtualized solution also gives excellent scalability to support operators’ future needs.

In terms of network performance, the solution should also support both single and multiple IPsec tunnels from the eNBs to the network core, which enables the use of flexible QoS network optimisation based on specific criteria such as the tunnel ID or service used – while making the security transparent to the subscriber.  This also enables the operator to offer dedicated IPsec tunnels to different customer groups – such as public safety users – to segregate different types of sensitive traffic from each other.

Using a flexible security platform that offers advanced IPsec capability and supports other advanced security applications, MNOs can protect their subscribers’ data and the network core against the risks of interception and attack, and easily manage the security deployment.  This in turn helps them to secure their subscribers’ data, loyalty and ongoing revenues.

Clavister has a range of backhaul security solutions you can see here.


Wireless Backhaul Trends for 2014

21 Dec

As many of us do this time of year, it is time to look forward to the coming annum and make a few predictions about our industry. We will address some of the concepts that you have been asking us about.

Backhaul Capacity

The irresistible growth of mobile devices will continue to shake the industry putting incredible strains on backhaul networks.  Many macro sites that were once huffing and puffing on 50 Mbps will require 300 Mbps. Some of these will even jump to 1 Gbps. Mobile network growth rates are requiring 20 times more capacity. There is no end in sight. The key words here are: more and faster.

Mobile Network Supply vs. Demand

Mobile Network Supply vs. Demand

Another key word is: expensive. Mobile operators are having a tough financial time going it alone. While they pay considerably to roll out faster and larger backhaul networks, the revenue picture cramps plans.

Wouldn’t it be nice if there was a way to cut the expenses associated with expanding backhaul? Well, maybe there is no Santa Claus, but there definitely is a solution to this conundrum.

Network Sharing

Many operators are combing their networks. Some are merging as companies. Others are merging the RAN and/or the backhaul.

Network Sharing Deals

Network Sharing Deals

The idea behind network sharing is always to achieve economies of scale that satisfy the demand for capacity without breaking the piggy bank. This trend is gaining in strength and will continue into 2014 and, practically, on every continent. Where 2013 was a big year for entering into network sharing arrangements, 2014 will be the big year for implementing them.

Schematic of Network Sharing

Schematic of Network Sharing

For more information about network sharing, please view our expanded overview here.

Small Cells

2011 and 2012 were the hype years of small cell deployment. Lots of talk but not a lot of action. However, in 2013, we saw a spurt in small cell deployment as operators have finally begun deploying small cells in large numbers. For example, Sprint in the US has deployed more than a million small cells with plans for considerable growth. AT&T about the same.  Vodafone in the UK has deployed hundreds of thousands. In fact, nine of the top ten mobile operator groups (by revenue) are now offering small cell services.

Informa tells us that small cell revenues will reach USD 22 billion in the next 3 years.

Global Small Cell Revenue by Deployment Type

Global Small Cell Revenue by Deployment Type

The Dell’Oro Group claims that the small cell market will just about quadruple by 2016. Infonetics informs us that the number of small cell units sold will grow 40-fold from 2011 to 2016. They also expect global small cell revenue to grow at a 73% CAGR during that time period.

We’re believers. The small cell revolution is upon us.

Small Cells Revolution

Small Cells Revolution

Cloud RAN vs. Small Cells

Cloud RAN is where we pool baseband devices and distribute the radio units. Ostensibly, it is cheaper to deploy thousands of RRU (remote radio units) than base stations. However, it costs a lot of money to link all these RRUs back to the baseband pool in the cloud.

Cloud RAN vs. Small Cells

Cloud RAN vs. Small Cells

Where fiber is plentiful and cheap, Cloud RAN is the way to go. This is true in dense urban environments and stadium situations. But at the same time, small cells have been touted as the solution to the same high-density traffic problem that Cloud RAN is designed to solve. Instead of pooling baseband resources, small cells distribute the baseband processing.

So what’s it going to be? Are we going to pool the baseband processing or distribute it out?

The Cloud RAN architecture is favored by operators with cheap fiber assets or in special situations like football events and rock concerts – high concentrations of subscribers in places where fiber exists.

We think that smart cells are going to expand mightily while Cloud RAN will be seen as a specialty where it makes sense. If there is cheap fiber and the cost of transport is no big deal, Cloud RAN is an attractive deployment scenario. However, for most operators, fiber is either non-existent or its cost takes too big a bite out of their operating budget. So, we expect most of the market to move toward small cells.

For more on the economic benefits of C-RAN, click here.

Software-Defined Networks

SDN is another interesting concept that, eventually, will make an impact. However, we are still at the stage of trying to define exactly what SDNs do, how to implement them, and how to operate them. As some have pointed out, while the cost of SDN equipment could be lower than today’s equipment, the changes at the core and in the initial deployment of such networks could more than offset the equipment savings. Operators who are watching their capex pennies might be slow to deploy. At least until standards are farther along.

SDN - Costs vs. Benefits

SDN – Costs vs. Benefits

In 2014, everybody will be SDN-ready to some degree or another, but significant conversions to software-defined networks will not happen.


Yes, friends, in 2014, the real fourth generation LTE-A is going to blossom in a big way. Yes, there are so many hurdles to overcome and, yes, there is so much money involved in getting these networks off the ground and into the smartphones of hundreds of millions of subscribers. But next year, we are going to see a lot of new LTE-A rollouts and 4G-enabled smartphones, tens of millions of them. The roll-outs will happen primarily in urban settings where the traffic and economics coincide with the benefits. LTE-A will be deployed with both FDD and TDD technologies.

3GPP Family Technology Evolution

3GPP Family Technology Evolution

LTE-A is going to be another giant contributor to the need for more capacity.

Multi-Core Wireless Equipment

Just like Intel did in the computer industry, giving us multi-core processors in our laptops, wireless backhaul equipment is going to adopt the trend and make multi-core a new standard. While multi-core in computers is primarily for speeding up processing, in wireless equipment, it provides an additional and very significant additional advantage: cores can be turned on remotely to boost capacity and/or signal strength without those very expensive and time-consuming site visits/truck rolls. Furthermore, multi-core radios can make more efficient use of expensive bandwidth.


Advances in Communications: New FSO provides reliable 10 Gbit/s and beyond backhaul connections

13 Nov

With 4G cellular communications placing increasing demands on backhaul capacity between cell towers, a new free-space optical (FSO) technology uses ultrashort pulse lasers for reliable high-bandwidth wireless communications in all weather conditions for backhaul “sweet spot” distances of 2 to 3 km.

Cellular carriers face a growing challenge to increase the backhaul capacity between cell towers to keep up with the rapidly increasing number of mobile users employing 4G technology to access the Internet. The only viable backhaul options for a full 4G network include deploying fiber-optic cables (which can be very time consuming and expensive), or installing wireless free-space optical (FSO) technology between cell towers.

Unfortunately, FSO signals can degrade due to the presence of fog and turbulence, which has prevented legacy FSO systems-that used continuous-wave (CW) lasers-from reaching the 2 to 3 km backhaul link range.1,2 However, experiments by Attochron with new FSO systems incorporatingultrashort pulse (USP) lasers show much better performance and can provide 1 Gbit/s backhaul capacity today and 10 Gbit/s and higher in the future without having to deploy fiber-optic cables.

Individual mobile Internet access and download speeds have progressed as mobile networks have evolved from 2G to 4G
FIGURE 1. Individual mobile Internet access and download speeds have progressed as mobile networks have evolved from 2G to 4G. Data rates displayed above and below show a range for that protocol. Individual mobile user download speeds will approach 100 Mbit/s in a full 4G network.

The backhaul bottleneck

As individual mobile Internet downloads increase from 2G speeds of 10 kbit/s to 4G speeds of 100 Mbit/s, the added outbound traffic places a tremendous strain on the cellular tower backhaul (see Fig. 1).3 Most cell towers depend on slower microwave backhaul connections that realistically top out at 100 Mbit/s, restricting how many users can be connected at 4G speeds (see Fig. 2). If a faster wireless technology can be deployed between cell towers, the number of 4G users can increase along with a corresponding increase in carrier revenues (see table).

Cell towers are presently connected to their core network by fiber-optic cables, copper wires, or wireless microwave links, which dictate mobile user capacity
FIGURE 2. Cell towers are presently connected to their core network by fiber-optic cables, copper wires, or wireless microwave links. Unfortunately, most cell towers depend on slow microwave connections (such as cell tower B). As more 4G mobile devices try to access the Internet from these microwave-connected cell towers, microwave speeds realistically max out at 100 Mbit/s and this capacity or pipeline must be shared with all of the mobile users connected to that cell tower.

A 20 Gbit/s fiber-optic connection to a cellular tower allows up to 200 mobile users to individually download from the Internet at full 4G, 100 Mbit/s speeds. However, former Verizon CEO Ivan Seidenberg claimed on the June 22, 2009 Charlie Rose Show that fiber optics will reach no more than 30% of a carrier’s footprint. JDSU marketing experts estimate that of the one million cell towers built by the end of 2014, 50% will require more capacity than any non‐fiber media can provide, and carriers will not be able to afford fiber optics—leaving 500,000 cell towers without a viable backhaul solution. The cost-effective wireless alternative to fiber-optic cables is FSO technology.4,5

mobile users accommodated by various backhaul technologies

Free-space optics

Legacy FSO systems work well in clear or hazy weather at distances up to 1.5 km, but the presence of fog can reduce effective link distances to 200 m.5 And while one option to improve visibility is to make the light brighter, this is not possible because the light then becomes unsafe to the eyes.6 Using flashing or strobe lights is another option; USP lasers behave similarly, but the pulses of light flash on a much shorter time scale—as short as a few femtoseconds.7

Qualitative differences between a CW laser and a USP laser are shown by infrared photography
FIGURE 3. Qualitative differences between a CW laser and a USP laser are shown by infrared photography. The false color photo is at the fiber end (start of transmission) and the black and white photo is at the receive end 1.25 km away. Notice the improvement to the pattern using the USP laser as the transmitter.

Infrared photography reveals qualitative differences between a CW laser and a USP laser both in the near-field and at 1.25 km (see Fig. 3). Experiments performed by Attochron (and supported in part by Lockheed Martin Corporation) at a 500 m wireless testing facility at the U.S. Army’s Picatinny Arsenal in Dover, NJ, demonstrated that USP laser-based FSO systems have an up to 25 dB increase in receive power over a legacy CW FSO system in fog (see Fig. 4). Other classified military research has observed 25 to 30 dB gains using an Attochron-specified USP laser in foggy conditions.

Quantitative measurement of a 25 dB difference in receive power between a USP laser and a CW laser at 550 m range is shown during high attenuation conditions (visibility less than 125 m)
FIGURE 4. Quantitative measurement of a 25 dB difference in receive power between a USP laser and a CW laser at 550 m range is shown during high-attenuation conditions (visibility less than 125 m).

These new USP FSO systems output a passively mode-locked 100 fs pulse at 1550 nm, with an average output power of 50 mW with a 1 Gbit/s repetition rate. The stream of ultrashort pulses is modulated externally to produce the gigabit Ethernet signal. In Picatinny Arsenal experiments, a single 3 in. telescope was used on the transmit side and a similar 3 in. telescope was used on the receiver side (see Fig. 5).

The hardware (a) of an Attochron USP laser-based FSO system is visualized in an artist’s concept (b)
FIGURE 5. The hardware (a) of an Attochron USP laser-based FSO system is visualized in an artist’s concept (b).

FSO signals are also subject to atmospheric scintillation that can cause receive-power fluctuations and fading and burst errors for longer link distances (similar to a star twinkling at night).8 We measured an increase in receive power of up to 15 dB in clear-air turbulence using a USP laser over a CW laser. These empirical observations correlate well to theoretical work done by G. P. Berman and colleagues at Los Alamos National Laboratory.9

This product design will incorporate four transmit apertures that allow more transmit power while maintaining eye safety. Multiple transmit apertures further reduce atmospheric scintillation because the four paths will independently sample slightly different portions of the atmosphere. These four paths will have different fluctuation patterns, and the summation of these four signals into the receive aperture will have fewer overall fluctuations.10 The receive telescope will be 8 to 12 in. in diameter and incorporate fine-steering mirrors for tracking.

In preliminary testing of our prototype USP laser-based FSO systems, the 25 dB additional margin improves link availability at 1 Gbit/s to 99.5% at 3 km; pulse modulation techniques now in development will further increase the bandwidth to 10 Gbit/s and beyond.

Pulse-shaping efficiencies

Pulse‐modulation techniques manipulate the laser pulse shape before transmission to achieve greater transmission efficiencies and optimize various desirable propagation effects. Binary phase shift keying (BPSK) pulse modulation has been used in satellite laser communication to increase overall bandwidth to 6 Gbit/s.11 Fiber-optic systems use BPSK, quadrature phase shift keying (QPSK), and 16-quadrature amplitude modulation (16-QAM) to increase bandwidth from 10 to 400 Gbit/s.

Since the USP is much narrower in time (100 fs), it has much broader spectral content than CW laser pulses in conventional fiber-optic systems. Our “pulseshaper” technology decomposes the bandwidth of a single USP laser into many discrete spectral “bins” that can be independently modulated, and then recombined to produce a new single pulse with a modified temporal shape.12 For example, by using 10 spectral bins, each with its own signaling, a 1 Gbit/s signal can be increased to 10 Gbit/s. Modulating 100 spectral bins will result in 100 Gbit/s overall.

Of course, the modulation and demodulation of these shaped USPs will require very fast digital signal processing (DSP). Fortunately, these DSP capabilities—which have been used in 100 Gbit/s and higher fiber-optic systems—are now available on an optical chip and will be incorporated in the USP FSO systems.

These advanced modulation schemes will extend wireless backhaul capacity to 10 Gbit/s and even 100 Gbit/s between cell towers. This will greatly speed the deployment of full 4G networks by cellular carriers and even be sufficient for future 5G cellular networks.13


1. W. K. Pratt, Laser Communication Systems, J. Wiley & Sons, New York, NY (1969).

2. I. I. Kim et al., SPIE Opt. Eng., 37, 3143–3155 (1998).

3. NGMN Alliance, “Guidelines for LTE Backhaul Traffic Estimation” (2011).

4. T. H. Carbonneau and D. R. Wisely, “Opportunities and challenges for optical wireless; the competitive advantage of free-space telecommunications links in today’s crowded marketplace,” Proc. SPIE, 3232, 119–128 (1998).

5. I. I. Kim, Lightwave, 26, 19–21 (2009).

6. “American National Standard for Safe Use of Lasers (ANSI Z136.1‐1993),” the Laser Institute of America, Orlando, FL (1993).

7. J. M. Hopkins and W. Sibbett, Sci. Amer., 283, 72–79 (2000).

8. I. I. Kim et al., “Measurement of scintillation for free-space laser communication at 785 nm and 1550 nm,” Proc. SPIE, 3850, 49–62 (1999).

9. G. P. Berman et al., J. Phys. B: At. Mol. Opt. Phys., 44, 55402–55421 (2011).

10. I. I. Kim et al., “Scintillation reduction using multiple transmitters,” Proc. SPIE, 2990, 102–113 (1997).

11. B. Smutny et al., “5.625 Gbit/s optical inter-satellite communication link verified in-orbit,” Proc. Ka and Broadband Communications Conference, Matera, Italy (2008).

12. See

13. P.E. Mogensen et al., “LTE-Advanced: The path towards gigabit/s in wireless mobile communications,” Wireless VITAE 2009, 147–151, Aalborg, Denmark (May 2009).


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