SDN and beyond

Software-defined networking (SDN) and network function virtualization (NFV) are new approaches to designing and operating mobile networks, granting operators better management possibilities and better use of the network capabilities.

NFV represents the virtualization of network nodes roles, which culminates in separate software implementations performing the functions typically executed by hardware components. At the other end, SDN uses the virtualisation technology to split the control plane (where you need flexibility) from the data plane (where you need speed/performance). However, the price for this is complexity which translates into high operation costs.

Operators benefit from such frameworks because they increase the network capacity and performance, and allow for better manageability.

The YateUCN approach recognizes the usefulness of separating the user plane and the data plane, but it implements both of them in software. The control plane is implemented in the user space for flexibility while the user plane in the kernel space for speed.

As a result, operators who deploy YateUCN networks will gain from considerably scaling down equipment, and will have better control over the network scalability and performance requirements. The image below shows the YateUCN implementation and a common SDN deployment using an OpenFlow switch.

Unified Core Network vs. Common SDN deployment

Common NFV/SDN implementations rely on virtualizing the EPC, so that the functions of the MME (Mobility Management Entity), the SGW (Serving Gateway), and the PGW (Packet Data Network Gateway) are each implemented in software and run on the same hardware. Drawbacks of this approach include:

  • the separation between the control and user plane is achieved by means of a switch, usually hardware-based and external to the network. This is a limitation of software-defined network functions;
  • the switch is designed to replace the PGW and obtain the IP connection which it sends to the eNodeB over the user plane. This means that it must support both GTP protocol for the user plane and IP which determines the high costs for such equipment.
  • the complexity of NFV requires additional effort from the network to accommodate it, which increases the overall cost of the solution.

The implementation of YateUCN differs significantly from the above.

First, it uses commodity hardware, so no special-purpose equipment needs is needed. Simply put, YateUCN is a COTS server, which completely diminishes investment, staff, space, and power requirements.

Secondly, YateUCN differs from virtualized EPC because it implements a unique software, based on Yate, that performs all functions of the MME, SGW, and PGW. All-software implementation also means that multiple protocols (Diameter, SS7) are equally implemented in YateUCN, and no additional implementations are required for the core to connect to the Home Subscriber Server or IMS. This helps operators cut down on highly specialized staff needs and facilitates inter-working with legacy networks.

Thirdly, instead of using a hardware switch, YateUCN implements it in the Yate kernel. Because the Unified Core Network is based on Yate, an expandable Linux-based telephony engine, it was possible to integrate a software switch in the core software, allowing for much faster data processing and eliminating the need to work with multiple vendors.

YateUCN core network solution removes the barriers of entering the market due to simplicity, scalability and low cost. YateUCN specifications features and specifications list can be accessed here.

SDR: the next big thing?

SDR systems can accurately be catalogued as ‘software-defined’ if they run on general purpose hardware, in a context where many existing technologies define themselves as SDR while running on special-purpose equipment.

With the adoption of more demanding technologies such as LTE, operators need to handle more traffic and deliver higher quality, meaning that mobile infrastructure needs to be run more efficiently and more profitably.

How can cost savings, resource efficiency, and flexible management be achieved in the mobile network? Our solution is the software-defined SatSite base station.

The reason for turning to SDR is the inflexibility of special-purpose hardware and software currently used in conventional base stations and what this entails in terms of costs, power consumption, and equipment.

sdr_2015-7-1_version6.3

Large expenses to upgrade, reprogram, or add new functions to the network

Because they are physically larger, base stations using conventional DSPs are more difficult to manage. What’s more, DSP boards can’t be modified to perform new functions or improve existing ones, so extending the RAN infrastructure usually requires new equipment to be added, leading to increased capital investment. Used on commodity hardware, SDR systems have lower manufacturing costs, making them more profitable when compared to the current heavy, static network equipment.

Increased power consumption

Special-purpose hardware products designed to perform complex functions come with high power demands. SDR allows more functions to be added to the same board, leading to the use of smaller equipment, with a lower power consumption.

Equipment supplier constraints

Another disadvantage of special-purpose equipment is that it is usually produced, serviced and supported by a particular vendor. In this case, operators are limited in recurring to different suppliers, as new equipment needs to inter-work with existing set-ups. SDR has the advantage of running on commodity hardware to avoid the use of specialized components and allow more flexibility to reconfigure or repurpose the hardware.

Dedicated staff training

Specialized hardware/software usually comes with specific vendor training and support. SDR offers operators more autonomy in configuring and managing base station equipment, relying entirely on their personnel.

SDR allows a high level of flexibility in designing and managing the RAN, with network functions being upgraded or reprogrammed with the simple use of software. While it is not a new concept, most base stations continue to use chip sets like DSPs, which are built on special purpose hardware, keeping equipment heavy, costly, and inflexible for changing traffic needs.

SDR is essential for the expansion of mixed networks to provide access across multiple technologies, such as 2G/4G, and prioritize service allocation depending on the needs. SatSite base station simultaneously provides 2G and 4G coverage using from the same equipment.

Built on general purpose hardware and using a non-proprietary operating system, SatSite allows operators to build smaller cell towers, with lower costs. SatSite cell sites can be suitably disposed to match the traffic needs in any area, and network performance can be improved remotely and easily, with a simple software change.

SatSite uses a high level language which enables it to support more complex functions than a conventional base station using a DSP. In highly populated areas or situations, increasing the network capacity to serve more subscribers usually requires a higher density of cell towers. SatSite can be dynamically reprogrammed to meet higher subscribers capacities by a software configuration for multiple-TRX.

Due to the flexibility, capacity, power and cost efficiency SDR brings to mobile networks design, its future probably holds good news.

Sources:

Wikipedia contributors. “Software-defined radio.” Wikipedia, The Free Encyclopedia. Wikipedia, The Free Encyclopedia, 24 Jun. 2015. Web. 2 Jul. 2015.

YateBTS and YateUCN™ make a perfect match for SDMN

YateBTS and YateUCN can be used together to build complete software-defined mobile networks.

YateBTS is a software implementation of the GSM/GPRS radio network. It runs on any Linux and uses a generic digital radio board, the Nuand BladeRF. The entire physical layer is implemented in software, which is different from the usual FPGA- or DSP-based radio design.

For the core network there’s YateUCN, the unified core network based on Yate. YateUCN is a Linux application that can run on commodity servers. It implements the functions of 2.5G and 4G core networks and is easy to integrate in existing mobile operator infrastructure. Like YateBTS, YateUCN replaces hardware routers and transcoders with pure software.
Together, YateBTS and YateUCN form complete software-defined mobile networks, networks that are affordable to build and operate, and networks that can support 2.5G, 4G or even both at the same time.
There are several advantages to the YateBTS+YateUCN approach:
  • Upgradable – We can add new features, like EDGE, with software upgrades or even replace 2.5G GSM/GPRS with 4G LTE using the same hardware.
  • Manageable – Because the entire system is Linux, we can monitor and manage every aspect of the software in a flexible way.
  • Affordable – A pure software approach has much lower development costs and relies on commodity computing hardware.
  • Flexible – The hardware is protocol-agnostic and can be reconfigured to support any mix of technologies.
  • Scalable – The capacity of the core network can be increased just by adding more servers.
Compare this to a conventional mobile network, with its hardwired base stations in the field and big iron like the Cisco AR550 or an Ericsson Mobile Switching Center in the core. It’s all single-purpose equipment, expensive or impossible to upgrade, and all based on proprietary software and hardware with big licensing fees, special training and support requirements.

Software Defined Mobile Networks

Since the inception of telephony, hardware drove the technological progress. In the early 2000s, generally available CPU’s became cheap enough to enable the development of software-defined radio (SDR) technology and software telephony switches (softswitches). However, it took nearly 10 more years to combine these two technologies and create the first software-defined mobile network (SDMN).

A mobile network can be called “software-defined” if it uses SDR base stations and a software defined core network for both telephony and packet data. A software-defined mobile network needs to be implemented on commodity, non-proprietary hardware, including the radio and network infrastructure hardware. In addition, an SDMN should use off-the-shelf, non-proprietary operating systems.

We may be the first company to offer a complete software-defined mobile network, and we are convinced that this is the future of mobile infrastructure.

More on SDMN: http://en.wikipedia.org/wiki/Software_defined_mobile_network