Point-to-Multipoint Wireless: Is It What I Need?

Many companies in busy urban areas of the UK, such as London, hit an uncanny barrier in the development of their network infrastructure as soon as they need to expand past the confines of a single office or a small campus. Deploying buried cables, even when economically feasible, is hampered by legal and administrative difficulties.

With mounting development costs, it’s becoming increasingly difficult for ISPs to meet their customers halfway with their leased lines portfolio. Alternative outdoors/wide-area wireless options, such as point-to-multipoint wireless links, are an increasingly common option under these circumstances.

Point-to-multipoint wireless technology is remarkably scalable and very reliable. It is used in scenarios that range from providing connectivity to IP security cameras deployed over a wide surface to providing a reliable, carrier-grade connection between multiple offices of the same company. In general, point-to-multipoint wireless connectivity is one of the options you should consider in scenarios such as:

• • You need to provide high-bandwidth connectivity to multiple sites where wired infrastructure is unavailable or impractical, subject to a radio survey, path analysis and the application’s latency and capacity requirements.
  • You need to provide reliable connectivity to several application-specific devices (CCTV cameras, access monitoring/logging devices) over a wide area, and you either cannot deploy or wish to avoid deploying a wired infrastructure.
  • You wish to ensure redundant, emergency connectivity to multiple sites, in addition to leased-line connectivity

Point-to-multipoint wireless connectivity is only one of the options you have in these cases. ACCL can help you choose the one that suits your company’s needs best. Check out our full range of wireless solutions.

In larger deployments, the base station will have a dedicated (often point-to-point) link to a core network, which relays data over much longer distances — tens or hundreds of kilometres. This scenario is called “backhauling”.

PTMP describes a network *topology* — i.e. how devices are connected — not a protocol. PTMP networks can operate using various protocols, such as LTE (licensed or unlicensed) or MPLS, which can carry regular IP data.

In other words, Ethernet or fibre networks can be freely interconnected using PTMP wireless links. The interconnect is transparent to the network devices.

There are three frequency ranges that are typical for point-to-multipoint wireless links:

• RF, in the 700-900 MHz region. Equipment operating in this radio region tends to require the least complex technology, but this is a busy region of the frequency spectrum, and only a small portion of it is deregulated and accessible to unlicensed users.

• Microwave, most commonly around the 2.4-2.7 GHz, 5.4-5.8 GHz, 10.5 GHz and 26-28 GHz regions. Much of the microwave spectrum in these regions is deregulated, but is often used for short-distance operation.

• Millimetre-wave region (58 – 90 GHz region). Equipment operating in this region is typically used for high-bandwidth applications, as the complexity of the installation and maintenance, and of the equipment itself, make low-speed operation difficult to justify.

Microwave-region PTMP links are the most common. They strike a good balance between spectrum availability and cost, and equipment in this class is reliable and reasonably easy to install and maintain.

What Can Point-to-Multipoint Wireless Technology Offer Me?

Speed and latency. A point-to-multipoint base station shares aggregate capacity across its subscriber units. Available throughput and latency depend on the selected equipment, spectrum, channel width, modulation, path quality, interference, endpoint count and traffic profile. Licensed or coordinated spectrum may be appropriate for some high-capacity designs; compare measured requirements and current product data rather than assuming a universal 1 or 10 Gbps result.

The latency figures of point-to-multipoint wireless links are worse than the latency figures of wired links. Exact figures are hard to give, as latency depends not only on link technology, but also on network topology, on the number of endpoints in the network, and on communication protocols. Broadly speaking, though, point-to-multipoint wireless links are sufficient for all but the most latency-demanding real-time workloads.

Reliability. Point-to-multipoint wireless links can offer carrier-grade reliability. In fact, mobile phone networks are point-to-multipoint — and most point-to-multipoint deployments for company networks operate under more favourable conditions, as the number of endpoints is usually fixed.

Cost. PTMP, private cabling and leased services have different capital, permission, maintenance, resilience and recurring-cost profiles. Compare them using surveyed routes, current supplier quotations, spectrum requirements, service levels and the intended operating period; no option is automatically the cheapest at a given distance.

Range. PTMP coverage is determined by frequency, permitted power, antennas, terrain and obstructions, interference, required capacity and receiver performance. Establish the feasible radius through path analysis, current product data and an on-site survey.

Higher-power equipment, operating in licensed areas of the EM spectrum, can reach much longer distances. However, a PTMP topology primarily enables connectivity in terms of *area*, not distance.

When long distances (tens or hundreds of kilometres) are involved, endpoints are usually clustered within smaller areas. In such cases, it is usually more feasible to network each cluster of devices using wired or PTMP links and interconnect the clusters using point-to-point links.

What Applications Is PTMP Best Suited for?

Point-to-multipoint wireless can be suitable for connecting several endpoints to a central base station. Endpoint count, range and service level must be designed around the selected platform, spectrum, path conditions, aggregate traffic, resilience and licensing requirements.

What Kind of Equipment Does a PTMP Wireless Network Need?

At a minimum, you are going to need to install a base station and at least one antenna. Most base stations today operate more than one antenna, though — typically, at least two or three — in order to provide better coverage and higher performance.

Using more antennas enables a better channelling of power in each direction, and more antennas can be used to transmit and receive data at the same time, from multiple devices (a mode of operation known as MIMO — Multiple Input, Multiple Output).

The antennae are usually grouped in a single array for easier installation, and the array is usually installed on a rooftop or a pole. The base station, or at least its RF unit, is mounted in close proximity to the antenna array for technical reasons.

Some subscriber units have an integrated radio module, which they can use to connect directly to the PTMP networks. More often than not, though, several endpoint devices will connect, via a wired or a short-range wireless link, to a separate radio module, with one or more antennae.

The base station and the radio modules deployed in the field need their own power sources. Nodes that need relatively infrequent communication can be battery-powered, but the base station needs a good mains (sometimes three-phase) connection.

It is usually a good idea to have some degree of redundancy and a battery- or generator-backed UPS at the base station end, as the base station is a single point of failure for the PTMP network. If the base station goes down, no two nodes will be able to reach each other.

When using the PTMP network as a leased-line replacement, you will also need a way to connect each office network to the multipoint wireless network. Technically, this would be done via a modem, but since this is a frequent deployment scenario, many equipment manufacturers offer PTMP base stations with integrated modems that you can easily integrate into your network.

Advantages and Disadvantages

The performance of point-to-multipoint wireless networks is sufficient for virtually every circumstance where short-, medium- or long-distance deployment is needed. However, it is still below the performance that you can get from a wired network, at a higher upfront cost, and more often than not at higher long-term cost as well.

Depending on the number of endpoints that you need to connect, on their type and capabilities, PTMP links may be a better option than connectivity via VPN or leased lines, especially in busy urban areas like London, where leased lines are expensive.

However, before committing to the significant investment that a long-distance wireless network entails, you should carefully analyse your requirements and your equipment’s capabilities.

The aggregated performance of point-to-multipoint networks is comparable to the performance of point-to-point networks. The two even rely on similar technology. The difference between them is in terms of network structure, in that point-to-point links are meant to connect only two endpoints.

Conclusions

Point-to-multipoint wireless networks are an increasingly common option for businesses that need to provide reliable, high-speed connectivity to multiple endpoints scattered over a wide area.

Although reliable and cost-efficient in the long run, point-to-multipoint wireless networks tend to have high upfront costs and require significant expertise for installation and configuration.

Not sure if a point-to-multipoint wireless solution is the right call for your business? We are here to help! Before making such a big investment, let our experts make sure that you will use it to the fullest. Get in touch with us and let’s schedule your FREE, no-obligations on-site survey! Our team will prepare a detailed report including our findings and recommendations so you can make an informed decision.

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