WiFi going software-defined


The role that software-defined networking (SDN) will play in the future of networking equipment and IT operations will continue to grow and evolve as end-users and their many devices place increasing demands on Wi-Fi infrastructures.

A problem for broadband operators and also OTT video providers is that consumer expectations are evolving faster than the service’s overall ability to meet them. For OTTs, the bottleneck is increasingly radiating out from the fixed broadband access back into the core network, but above all into WiFi for the final hop. Even primary TVs are starting to be served by WiFi if they are web connected or using HDMI dongles and so that has become a focal point for efforts to deliver guaranteed QoS for premium services.

When WiFi is serving just one or two devices in the same room as the Access Point (AP) then performance is not an issue and is hardly any different from a direct Ethernet connection. But when the devices are scattered around a large house on different floors then usually some wired assistance is needed, using say MoCA or Powerline as a kind of backbone.

But operators still lack the end to end visibility extending over the WiFi network, with performance still subject to contention for example if many users are accessing high bit rate streams at the same time. As WiFi becomes increasingly ubiquitous, opera-tors would ideally like to reach into the WiFi and configure a link to a given device for a session, as some are starting to be able to do over the fixed broadband infrastructure. Here is where the emerging technology of Software Defined Wireless Networking (SDWN) comes in. This is SDN (Software Defined Networking) extended to the wireless domain, with potentially even greater scope for manipulating bit rates and QoS, but also additional technical complexity. SDN was motivated originally at the enterprise level by the drive for cost savings through use of commodity hardware and agility through being able to configure capacity for new applications faster.

SDN is important to network planning because of two of its essential qualities. First, because SDN separates the control and data plans in network equipment, it enables networks to become dynamic, flexible, cost-effective, and adaptable as the demands made by applications grow. Second, because SDN shifts the focus away from the underlying layers of services and creates network functionality based on policy rather than quantitative management console settings, the underlying infrastructure can be abstracted for applications and network services.

SDN also enables differentiated QoS by separating higher level traffic control from underlying packet forwarding. In the wireless domain the ability to configure the network to optimize QoS for individual streams will be particularly valuable, because this has been largely lacking to date. In truth SDN alone does nothing to achieve this because it requires developments at the physical network level, which means here around mesh networking and distributed beam forming. The point about wireless is that performance is subject not just to pre-configured capacity but also varying factors such contention, the location of client devices and in the home changes in furniture layout or structure. Distributed beam forming attempts to overlay some order by enabling several clients to come together to form virtual antennae arrays that can then optimize their signals to target individual devices. The role of SDWN then would be to give say a broadband operator visibility and control over the configuration of these virtual arrays and in effect establish a guaranteed end to end connection with a target device.

SDWN then does have an additional ingredient over fixed line SDN, which is the active participation of the client in the process. This gives additional scope for improving coverage and QoS not confined just to cooperating as a peer in beam forming, but also participating actively in spectrum and channel allocation.

Software defined wireless can also manipulate the spectrum itself for traffic prioritization, with the potential to combine that with distributed beam forming to yield temporary boosts in bit rate for a given device. It could boost bandwidth by tuning into multiple frequencies simultaneously, a bit like channel bonding over fixed networks.

But the biggest benefit will come through greater ability to cope with the real world of fluctuating bandwidth in such a way that adequate QoS is ensured. The key is that the service provider will have the ability to alter the behaviour of the “wireless last mile” as quickly as the conditions change and therefore stay in charge, rather than reacting after the event as at present.

One thing about the future of Wi-Fi is clear. SDN will contribute to the development of organizational networks from access at the edge all the way to the core. Because networks are primarily being accessed by wireless devices, SDN will play an essential role in wireless LAN implementations. Based on the work currently being done by vendors in this area, next-generation Wi-Fi is sure to keep pace with technology advances in SDN.

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Mr. Fellah, is a Senior Analyst and founder of Maravedis with 20-year experience in the wireless industry. He authored various landmark reports on Wi-Fi, LTE, 4G and technology trends in various industries including retail, restaurant and hospitality. He is regularly asked to speak at leading wireless and marketing events and to contribute to various influential portals and magazines such as RCR Wireless, 4G 360, Rethink Wireless, The Mobile Network, Telecom Reseller to name a few. He is a Certified Wireless Network Administrator (CWNA) and Certified Wireless Technology Specialist (CWTS).