The developed world and a number of developing nations have or are on the road to becoming  hyper-consumers of mobile and fixed line data, as they use the Internet for an increasing number of bandwidth intensive services and applications, writes Wayne Coetser, optical networks solutions architect at Nokia Siemens Networks.
Communication service providers (CSPs) are therefore constantly looking for ways to improve the efficiency and capacity of their networks, while simultaneously reducing capital expenditure and operating costs.
This means that building out networks is not always the answer, so a number of CSPs are now looking to improve existing networks through optimisation, to future proof their sunken investments into infrastructure.
Many CSPs are turning to multi-layer optimised (MLO) networks, where a dense wavelength division multiplexing (DWDM) layer, an electrical switching/aggregation layer and an (IP) layer are combined to reduce capital and operating expenditure and deliver the lowest total cost of ownership (TCO).
However, there is a complex relationship between these layers that doesn’t allow for a one-size-fits-all solution for network optimisation. The optimum solution for any given network depends heavily on a number of factors, such as the legacy equipment in place, the future plans of each CSP and the services deployed.
So, as this demand for bandwidth grows, often much faster than revenues, CSPs are faced with the decision of either building out more capacity, or installing bigger routers connected directly or via static DWDM connections to satisfy these burgeoning bandwidth demands.
However, this can often increase network costs to unacceptable levels.
In addition, CSPs are starting to realise that the supposedly simple solution of transporting all services over an IP network often adds to the problem, because different services demand a different quality of service, which places an extra burden on the routers, as well as demanding skills which might be in short supply to configure and operate the network.
As a result, the debate around how to future-proof existing networks is heating up and, with market share and equipment prices at stake, it is a debate that is often more political than technical.
The truth of the matter is that there is no single preferred network design that results in a unique, future-proofed, TCO-minimised network for all applications. Instead, designing good networks is, and has always been, a highly customer-specific MLO undertaking, which must consider the future ambitions and legacy networks of each CSP.
For instance, applying the MLO rules to mobile backhaul is playing an important role in the migration to next generation mobile networks, like HSPA and LTE. When optimising the evolution of mobile backhaul, user are not simply looking at the transmission part of the network.
Instead, they are optimising the network end-to-end, taking into account the evolution of the base stations, the core and the overall mobile network architecture.
The more typical transmission networks currently in use can also benefit from MLO as they are a layered combination of DWDM equipment, which is the lowest layer above the fibre, a sub-wavelength aggregation and grooming layer, and an IP layer.
These layers form server/client relationships and are independent of each other. From a technological point of view, the functions of each layer in the transport network are very different, with higher layers more expensive due to the greater processing requirements. As such, the use of these layers must be carefully balanced to deliver cost-optimised networks.
Finding the optimum level of integration is a vital important issue. An integrated solution often makes sense but, in many instances, so does separating the layers and connecting them using standardised best-of-breed interfaces.
Obviously there is no “black and white” answer to this decision, since there are valid arguments both for and against increasing integration. On the plus side, more integration can often bring down the cost, and combining technological elements can also offer the best fit for a particular network.
However, on the down side, integration does not allow independent evolution of the layers or equipment, hampering the speed of development. Different items of equipment have different lifetimes and integrated equipment will only last as long as the most short-lived component.
Bespoke combinations require different operational procedures and training, and replacing or reusing them could be difficult. It also makes multi-vendor networking more complex. So, while integration may look attractive at first glance, it may become a burden and increase TCO over the lifetime of the solution.
To solve these issues and find the best solution, CSPs are turning to partners who can effectively implement MLO solutions through their understanding of the network needs and their use of sophisticated planning tools to distribute the workload optimally between the different network layers.
Designing optimum transport networks also requires a combination of experience and the right tools, and starts with an end-to-end optimisation strategy that includes all the suppliers and technology in the transport network value chain, like base stations and video servers.
In this regard a vendor independent consultancy service can be hugely beneficial when it comes to optimising and improving the performance of both fixed and mobile networks.
CSPs also need equipment that integrates well, whichever vendor is supplying it, and should choose a primary supplier who is willing to provide neutral, consultative support and integration services. The right partner should also be able to provide an experienced team to install and commission new equipment and coordinate network operations.
They should also help to make the most of network assets throughout their lifetime, as good networks alone can’t guarantee business success.
Networks have to be designed to support a CSP’s business strategy and are highly CSP-specific, so CSPs need to partner with service providers who understand this and can help to find and implement the right solutions to control churn, meet the growing demands on the networks of today and build towards a sustainable and effective future.