California-based wireless system provider Ruckus Wireless unveiled its new SmartCell radio products at Mobile World Congress 2012. The products are designed to address the growing need for multi-technology networks where service providers combine macro cellular networks with LTE small cells and Wi-Fi cells.
The SmartCell is a heterogeneous small cell wireless edge system that lets operators inject wireless capacity, increase coverage and enable new edge services, while at the same time relieving radio access, backhaul and core infrastructure bottlenecks created by the rising demand for data on their networks.
While LTE small cell networks will help relieve that pressure, Ruckus believes it will not be enough and that Wi-Fi will still be required for data traffic offload from the main networks and for backhaul. By integrating Wi-Fi and LTE small cells within the main cellular core, operators will be able to optimise network utilisation across the radio access network. This will help them provide performance improvements and create a seamless experience for subscribers as they move from one technology to another.
Integrating Wi-Fi into core cellular networks is one of the key themes beings discussed at MWC, but Steven Glapa, Senior Director of Field Marketing at Ruckus Wireless, is firm that ‘vanilla Wi-Fi’ will not be sufficient to provide carrier grade services.
‘The mobile carriers get that Wi-Fi needs to play a very important role in their business, but it can’t be any old vanilla Wi-Fi,’ says Glapa. ‘If you talk to Ericsson, Alcatel-Lucent, NSN, Huawei Samsung and ZTE, who are responsible for supplying the carriers’ licensed band product portfolio, they are being forced to add Wi-Fi by their carriers customers.
‘They say, ok, any old Wi-Fi will do. We’ve seen the specs for Wi-Fi contributions coming out from them and it is clear from the RFPs that none of them know how to do Wi-Fi. They are clearly not talking to the same people in the carrier community as we are, or if they are, they are not listening,’ says Glapa.
He attributes this myopia to the often poor experience many people have with Wi-Fi in airports or hotspots leaving them with the perception that Wi-Fi just isn’t that good, so don’t expect anything better.
‘Most of the time they are just buying the same old Wi-Fi: the chip set from a Marvell or Atheros source, plus a reference design that they develop that says analogue radio bits on the front and a dumb antenna and that’s Wi-Fi,’ says Glapa. ‘There is no intellectual property there besides the chipset.
Carrier grade Wi-Fi
‘Ruckus is an entirely different beast,’ he insists. ‘We developed out of TV broadcast quality Wi-Fi, so we have the ability to make that happen. Ask The Cloud in the UK. They tested the other Wi-Fi guys and us and the result is we are the sole vendor for the complete overhaul of their network – that’s tens of thousands of nodes – and those guys know Wi-Fi really well.’
Glapa says that Ruckus’ ability to handle high densities of simultaneous users in areas like stadia is because its system has more capacity than its rivals. He cites the example of the Rockefeller Center’s Skating Rink in New York, where NBC TV holds its Education Nation event every year bringing together education leaders and government.
NBC was worried that it wouldn’t be able to supply the bandwidth for all the people trying to communicate through their mobile devices. NBC has a relationship with Verizon as the network provider for an OC-12 (optical carrier) pipe going into the Rockefeller Center.
‘Verizon’s incumbent Wi-Fi provider said, “no thanks”, as there are 350 access points (APs) around here, the noise floor is near 65dbm, which is about the threshold beyond which you can’t do anything with Wi-Fi at all,’ explains Glapa. ‘So, they asked us and we said, yes. We installed six APs and delivered 200Gb of traffic in two days. Verizon really couldn’t believe how good it was, so we have friends at Verizon championing us now.’
Wi-Fi integration into carrier networks with SmartCell 200 gateway
Last year Ruckus introduced its Wireless Service Gateway (WSG), which provides a translation between Wi-Fi and cellular networks. Glapa describes it as like a beachhead for creativity between the two.
It has now produced an upgraded version, called the SmartCell 200, which is a highly scalable small cell HetNet (heterogeneous network) edge gateway capable of supporting hundreds of thousands of Ruckus or non-Ruckus APs and millions of clients, as well as providing standard-based 3GPP integration into existing and future mobile core infrastructure.
‘This year we are taking it another step,’ says Glapa. ‘We are taking Wi-Fi into the mobile core, but also integrating cellular capability inside the end node devices, so we can do combined licensed and unlicensed Wi-Fi small cells (see SmartCell 8800 below). We are extending the functionality of the gateway device for a richer integration of Wi-Fi and support for small cell licensed band technology (LTE, for example) as well. So, our gateway box has got stronger and smarter.’
Glapa says the end product came out of a year’s worth of evaluation work with about 30 carriers around the world. ‘The carriers are learning where the key requirements are in terms of integration: authentification of subscribers and devices, but also integration into the business back end; session tracking, policy enforcement, billing integration and the like – it’s almost an application layer.
‘You also have to manage a connectivity layer,’ he continues, ‘so you need to minimize the disruption to the existing GGSN (gateway general support node) policy enforcement box and so on. There are different modes in the standards where you are tunneling, such as 3GPP. The other theme is sorting out all the back end stuff and ways to plug in. We are bringing the Wi-Fi to where the operator is and treating it as more radio capacity,’ says Glapa.
Authenticating non-Sim based mobile devices
The other issue the new version of the WSG has addressed is how to deal with tablets and mobile devices that do not have Sim cards. ‘Actual authentication, billing and tracking of a subscriber requires a unique identifier of some sort and a Sim card is the most convenient thing, but if you have no 3G interface – then what?’ asks Glapa.
‘There is no back end to authenticate non-Sim based devices. But we have a way of doing that in our SmartZone. The next version of our WSG enables the operator to do that.’
Exactly how it does it is not easy to explain. Glapa says: ‘The simple way to look at it is: it is very difficult to introduce changes to a subscriber base for a mobile operator. In order to include non-Sim based devices they have to take their definition of you and extend it to include a list of other devices. In the SmartZone we have the ability to extend the subscriber database in ways that allow you to take care of that.
‘Some of it is the definition of a subscriber and some of it is how you handle their authentification,’ continues Glapa. ‘It is like an automated versions of the portal you use in an airport when logging on to Wi-Fi. That same kind of interaction has to happen in the system somewhere – we call it a subscriber gateway. It also allows the device to decide which Wi-Fi to choose when establishing the SSID. The AP will tell the device: here’s the list of Wi-Fi providers and automatically chooses one that the user’s mobile carrier has a relationship with.’
SmartCell 8800 outdoor multi-radio
In addition to the upgrade to the WSG, or SmartCell 200, Ruckus also unveiled its new small cell product: the SmartCell 8800 – a multi-radio outdoor access node, which integrates 3G, 4G, Wi-Fi and backhaul in a single, lightweight, small form factor. The SmartCell 8800 is ready for trials now and is expected to be commercially available in the second half of 2012.
The SmartCell 8800 is a dual-band 802.11n Wi-Fi with an optional add-on module for Ruckus or third-party 3G/4G radios that share integrated power and backhaul. This will allow operators to deploy Wi-Fi with smart mesh backhaul today and upgrade to Wi-Fi with LTE, as and when desired without any mounting or backhaul changes.
It also supports the 802.11u standard for seamless roaming between Wi-Fi and 3G, integrated GPS auto-location, smart meshing, predictive channel assignment and always-on WLAN spectrum monitoring.
Being able to combine different wireless technologies in the smallest possible box is going to be of vital importance as small cell networks proliferate at street level. ‘If you think about what the operators are trying to do with networks in a public place, the municipalities are saying: ok here’s your pole, you get to put up one thing only,’ says Glapa.
‘That one thing, based on what they need to do from a capacity perspective, needs to have 2.4GHz Wi-Fi and 5GHz Wi-Fi to support 802.11ac when that comes and it needs to have a cellular radio and wireless backhaul if you can’t get fibre to it – so that is four radios in a box,’ points out Glapa.
Trying to fit conventional antennas into a small form factor is no easy task. Glapa says that Ruckus has developed little antenna matrices that give very high performance in a very compact package. ‘If you have four radios, that’s 11 antennas if you do it conventionally, so 19 different antenna elements in the box. You can choose them combinatorially to get the best connection at any one time. That’s how we get the 2 to 1 difference in performance compared with other vendors.’
He continues: ‘The other thing this gives you is a lot of performance and a lot of antenna presence in a very small package. So the 11 antennas it would take in a conventional approach to deliver 2.4MHz and 5MHz Wi-Fi, backhaul and licensed cellular technology we can put in this box and there is nothing else you have to add. The other guys have a box that big, but you have to stick many antennas around the outside to support all those things.
Wi-Fi for backhaul
The cellular industry has always regarded Wi-Fi as too flakey for backhaul. But Glapa says Ruckus has done trials with one of the largest European multi-national carriers using Wi-Fi for small cell backhaul, including supporting voice calls, on a small cell, which is bigger than a femotcell and smaller than a microcell, and over three hops of Wi-Fi mesh in an urban environment. ‘It did just fine thank you,’ he says.