15 May 2019
Jon Howell investigates the challenges of in-building wireless
Ever since the introduction of smartphones the demands on mobile networks have increased and each device is now capable of consuming ever-increasing amounts of data.
The pressures are only going to increase. There is still plenty of expansion left in Africa for the adoption of smartphones. For example, in countries such as Tanzania although over three quarters of the population own a mobile phone less than a fifth of those are smartphones. Even some of the most mature markets in the continent, such as South Africa, still have a sizeable potential for growth of these data-hungry devices.
Keeping up with demand
As you would expect, mobile operators are rising to the challenge by beginning to look at 5G. Both Vodacom and MTN have run trials in South Africa and Rain, a data-only network, launched at the end of February in the country. This makes South Africa one of the first countries in the world to launch commercial 5G services.
However, it’s not just a new generation that is going to help out. “Operators can increase their number of mobile cells, as that will enable them to service a larger number of simultaneous users,” says Joe Chiou, vice president, Zyxel IBS Business Unit. “For increasing data demands there are two ways through which smartphone users can obtain faster data speeds.
“Firstly, there is MIMO: multiple-input multiple-output. With multiple antennas, each can act as one communications channel and each additional channel can add to the data transmission speed. Secondly, there is carrier aggregation. This technology allows the smartphone to communicate with multiple carriers (wireless signal distribution devices, such as cell towers) at the same time.” Carrier aggregation would mean that a phone which can support multiple bands, such as 900MHz, 1800Mhz, and 2600MHz, could be talking to three separate towers using each band to avoid signal interference.
So, operators will have methods to increase the bandwidth available to users, but the pressure will come from more sources and indeed in new ways. You only have to look at how wireless networking has changed in homes to see the problem.
“In-home networks have to keep up with more and more devices - from smartphones and TVs to household appliances - all wanting to access the internet, especially since most of them need high speed connections and high bandwidths,” says Sebastian Richter, director of product management for home networking at Devolo. You might think of Devolo as a consumer firm, providing power line Wi-Fi extenders, but they also have a commercial arm where similar products are put into use to solve in-building wireless connectivity issues for businesses.
Businesses won’t see their in-building networks struggling under a plethora of Wi-Fi enabled fridge freezers, though. “The primary driver for network growth is connected devices for IoT applications in the home and in the community, including imbedded smart nodes for home controls, public safety and connected automobiles,” says Keith Pennachio, EVP at Squan.
Technology such as connected automobiles might seem far off for now, but the rise of IoT has already exceeded 21 billion devices worldwide in 2018, expected to rise to 50 billion by 2022, according to Juniper Research.
As Mervyn Byleveldt, solutions sales manager Africa at Cradlepoint, says, “Smartphones aren’t the only consideration for indoor wireless networks, organisations need to consider CCTV, failover for retail outlets, vending machines, ATMs etc.” So, the proliferation of devices wanting to share the network is going to be an issue, but it doesn’t stop there. “When it comes to the smartphone, too much is still never enough. With the imminent rollout of 5G and increasing demand for unlimited data, we are starting to see new consumer behaviours,” warns Byleveldt
This shows that there will be demands that might not even be predicted yet. Apps or services which may suddenly strike a chord with users. Maybe it will be a new platform, something that can be data hungry like WhatsApp with its video calling, which will suddenly have users chewing through more bandwidth than ever before. So, what can operators do to prepare for this?
5G to the rescue?
Just like 3G and 4G, 5G is going to offer faster data rates and lower latency. Over the three generations, maximum data rates have increased from 42mbps to 1gbps to 10gbps and latencies have dropped from 100-500ms to 50-100ms to 1-10ms.
“Mobile carriers need to start preparing for their pathway to 5G and start their adoption of Gigabit-Class-LTE with a combination of cloud-based applications and services. We are seeing increasing numbers of devices that need to access networks, meaning that additional network on-ramps will be needed as well as remote, cloud-based network management,” says Byleveldt. He also predicts that the adoption of 5G will be even faster than was seen for 4G.
However, Pennachio is more reserved: “Some network operators have taken a ‘Build it and they will come’ approach, while others have been more reserved in their rush to claim success with 5G. Use cases for faster speeds and lower latency are still coalescing around the need for more clearly defined ROI.”
There are also lessons to be learnt from existing technology, such as LTE. “While traditional LTE is already widely recognised by mobile and distributed enterprises as a critical business enabler, one potential drawback is the potential for radio spectrum interference in densely crowded areas like urban centres and stadiums,” warns Byleveldt. “Today, cellular carriers are aggressively deploying small-cell radio access nodes in many urban centres in concert with their efforts to expand their LTE-A coverage.”
On the plus side, existing networks should be able to add 5G, at least for outdoor networks. “Towers can be upgraded, equipment rooms can be expanded, and fiber can be overbuilt. Most 3G and 4G networks are upgradable, through a mix of equipment adds and backhaul augmentation,” says Pennachio.
Unfortunately for 5G, and those who are hoping it will solve their in-building wireless connectivity issues, is that the new technology has some severe drawbacks. Alastair Williamson, CEO of Ranplan, explains, “5G signals will be deployed using the C-band (3GHz-5GHz) and mmWave frequency bands (26-28GHz); and as such have shorter ranges compared to sub 3GHz frequency bands currently employed by 4G (LTE). With these higher frequencies, 5G signals will find it even harder to penetrate most building materials such as steel frames, glass, insulation, and wood, leading to increased penetration loss if outdoor 5G macrocells are used to cover indoor areas.”
To provide some technical data to show how much of a problem this will be, C-band frequencies will generate an additional 8-18dB wall penetration loss and it’s even worse for the mmWave band which will generate over 80dB wall penetration loss. So,it’s not going to be feasible to rely on a mobile operator’s outdoor network to provide coverage for office blocks, shopping centres, campuses, or stadiums.
There’s also bad news for those who are hoping that 5G might come to their current in-building DAS solution. “Most existing indoor networks are passive DAS and cannot be upgraded to 4G/5G,” says Zyxel’s Chiou. “Likewise, existing Wi-Fi equipment cannot be upgraded to support 5G through firmware. To support these new technologies, modern equipment is required.” So, it could be that you’d be looking at a building refit, which could be expensive, or to have a repeater in the building, to bring the outdoor network inside, but there are problems with that approach too.
Solving the problem
Some existing networks will have extra capacity available, others might need ‘rip and replace’
“There are numerous issues to consider when deploying an in-building solution,” says Chiou. “How large is the building? Is the building to-be-built or existing? Which parts of the building needs signal provision/strengthening? What is the building layout? Which operator(s) do we want to support? Which operator is or is not willing to pipe a signal source to the building? What cellular technologies (2G/3G/4G/5G) do we need to support? Is it better to use a Repeater, a DAS, a small cell, or a combination thereof? So what’s the client’s budget?”
Certainly, if you are in the position to be designing a network for a building that is still yet to be constructed then that gives you much more flexibility in the planning. This gives you the potential to feed back into the plans before work starts, possibly suggesting the use of different lighting or separating wall material to reduce interference and signal loss. Although there are limits. “Given that seven stories are considered as a reasonable maximum for outdoor signal penetration from street level, people in tall buildings may get a good view but no connectivity,” says Williamson, reiterating at how even for new buildings that there are limits on what outdoor wireless networks can achieve.
You also need to consider what your goals are. “You need to address the tenant or owner’s need,” says Pennachio. “Maybe it’s public safety or mechanicals monitoring/proactive maintenance, then again it could be something more wide-ranging such as improving the existing wireless coverage. Once a use case is established, it is critical to understand the cost and logistics of designing and building a system. Questions around ROI, who will fund, who will operate and who will manage the network once deployed are all questions needing to be answered.”
Pre-existing installations or old buildings can make things more difficult. “The ‘problem’ with older venues is that they typically have older in-building solutions installed, most likely in the form of 2G/3G passive DAS. And the problem with those is that they cannot be upgraded to provide 5G and cannot fully support 4G (uplink signal loss and inability to support MIMO being major issues).,” says Chiou.
“Adding such support will mean a separate DAS (active DAS, due to above reasons), and most older buildings - with their pipes already full from decades of installing this and that - simply have no more room,” he continues, before suggesting that Zyxel’s active DAS solutions can help because they use CAT5 cables in lieu of coaxial or fibre optics. “Unlike coaxial and fiber, CAT5 cables are easy to handle (thin, light, highly bendable), easy to install, and easy to afford. Installing ZoneDAS is basically the same thing IT cabling and Wi-Fi planning!”
There are other solutions to help with old buildings which don’t have space for new networking cable deployments. “It’s important to avoid ‘dead zones’ and this can best be achieved through a combination of powerline communications and Wi-Fi with mesh functionality and additional ‘smart’ features,” says Devolo’s Richter. “This solution combines the best of two worlds: powerline communications as the backbone uses the existing wiring to transmit data across the entire property, without the signal being blocked by thick walls or ceilings, and the latest generation of G.hn-based products recently made a huge step forward in terms of speed.”
Pre-existing wireless networks will also cause problems, unless you are in the lucky position of being able to ‘rip and replace’ the whole network. “As the number of wireless network installations increases on a daily basis, the potential for signal interference is becoming a serious threat to the reliability of new and existing wireless broadband networks alike,” says Byleveldt. He warns that you absolutely must take into account all the possible sources of interference, if you want to provide a seamless service. “The key is to choose the right equipment that can dynamically adapt to congestion and interference; older buildings tend to have more interference factors like steel and concrete rather than dry or temporary walling, and fluorescent lighting rather than the LED lighting newer venues might have.”
DAS is all?
Distributed antenna systems (DAS) have often found favour for solving in-building networking problems. The central idea of replacing one big antenna with multiple low-powered antennas linked over a transport medium solves many of the problems which buildings raise. Each antenna can be placed to work around the penetration losses that internal walls can cause and reach what would otherwise be dead zones.
It certainly seems as though DAS will remain a relevant option to be considered for deployments. “Distributed antenna system (DAS) network solutions will continue to play a role in the effort to expand network connectivity for the foreseeable future,” says Byleveldt.
There are certainly benefits to DAS. Pennachio explains: “DAS utilizes a RAN architecture, which is highly secure and adaptable across a broader platform of wireless applications. Think about a user moving from their mode of transportation and crossing the transom of any facility while maintaining connectivity and without interruption of use.” Certainly, much like unified communications, the seamless hand-off from one wireless technology to another has not always been easy to accomplish.
Chiou also raises the point that DAS solutions have traditionally been expensive, difficult to install, and complex, although he points out that Zyxel’s ZoneDAS/SlimDAS uses Cat5 cabling which can help with the cost and ease of installation. He suggests that some sites might be better served using small cells, because they can live with small cell limitations: each small cell supports one operator only, and supports just two cellular technologies (pick 2 from 2G/3G/4G; no affordable 5G small cell exists yet). Ultimately though he still believes in the power of DAS. “However, because most building cannot accept small cell limitations, because many are too big or populous to settle for repeaters, and because passive DAS is unable to support newer technologies, active DAS is still the best solution (or part of the solution) for medium/large scale in-door needs,” he recommends.
Small cells are also suggested by Cradlepoint’s Byleveldt. “DAS’s role in smaller indoor and outdoor venues is likely to be reduced as small cell technology continues to mature and evolve. Although DAS technology is currently the preferred method for larger venues, some advancements in small cell network technology will allow them to support additional bands and carriers, making them more competitive with DAS systems,” he says.
However, Chiou still sees them as a less than ideal solution. “Small cells (including picocells and femtocells) are good in that they are designed to be a part of cellular networks. But they are meant to be sold to operators, and strengthen the networks of only single operators,” he says. “As a result, they are widely used outdoors, where they help operators complete their grids, and a lot less suitable for indoor applications, where we want single devices to provide signals from all of the area’s major operators. Imagine installing multiple sets of four small cells all over a building, just to make sure that users of all four cellular operators can stay connected! Also, because each small cell is an independent cell site, areas with overlapping small cell support will experience interference and poor signal.”
It’s all about planning
The proliferation of smart devices is putting ever greater strain on in-building wirless networks
Yet another solution is that of heterogeneous networks, or HetNet for short. These networks are comprised of a combination of cell types and different access technologies. The basis tends to be a cellular network, with its various generations of systems (2G-5G), with macrocells being complemented by microcells, picocells, and femtocells in order to fill in coverage or provide extra bandwidth in particular areas. Then HetNets also add Wi-Fi into the mix.
So, it might seem as though there is no simple solution for in-building wireless connectivity. Ultimately there are different choices which are applicable to different ages and sizes of buildings. Various implications depending on how many people use the build and how many IoT devices (and other automated connected devices) are on the network too. However, there is one thing that all in-building networks can benefit from - planning.
As Byleveldt says, “Determine where users will congregate, the type of Wi-Fi-enabled devices they’ll be using, as well as how they’ll be using them. Another key step you should consider is to do an active site survey at the venue prior to equipment deployment. This step will help you determine optimal network reach.”
Active site surveys are valuable, but there is a lot you can do from the comfort of your own PC. Williamson explains how Ranplan’s products can take a lot of pain and legwork out of network planning. “An indoor solution has to be built around small cells or DAS networks, while also integrating seamlessly with Wi-Fi networks. For effective radio planning inside buildings, the structure has to be defined and modelled in as much detail as possible, including a detailed knowledge-base of propagation characteristics of different materials and the leakage out into the external environment, potentially causing handover issues.”
Ranplan has In-Building and In-Building Lite, the latter aimed at small or medium-sized enterprise projects. There is support for multiple technologies, such as 3G, 4G, 5G, NR, IoT, Public Safety, and Smart Cities. Passive DAS, small cells and Wi-Fi are included, so a network designer can try out different possible configurations.
The product information promises an advanced propagation engine with 3D ray tracing to calculate a coverage map. It’s possible to get a feel for how actual hardware will respond because there is a live database featuring multiple vendor-approved components that are validated and compatible for all wireless technologies.
Ranplan isn’t the only firm that has network planning tools, obviously most vendors of access points (AP) have their own coverage tools to help you choose the correct number of APs for your situation. However, the best way to find which solution is right for you - DAS, small cells, a HetNet, Wi-Fi - is to plan before you buy.
