Most Network Managers know that microwave radio links require a clear line of sight and access to spectrum, but to achieve a successful link that is going to deliver service 99.999% of the time the devil is in the detail.
In-house vs. Managed service
You may choose to do it yourself, with your own trusted team of experts, and subcontract each step to the most cost effective company, or you may choose to use a company that offers a complete turnkey service.
You can use unlicensed or light-licensed spectrum, but you risk the link failing in the future due to interference. For an interference free wireless service you need private spectrum. You can obtain private licences from Ofcom for a few thousand pounds and subject to availability. Alternatively if you are going down the managed service route your supplier will deal with this for you, or better yet they will own their own licensed spectrum which makes the process of obtaining it infinitely quicker and it offers lower risk.
Even if you use light-licensed spectrum for rapid deployment at less cost, you would need an operator licence to give you a high level of visibility when it comes to other planned uses of this spectrum.
Desktop Line of Sight
This can be carried out by looking at the lie of the land on a map to see if it is theoretically possible to get a line of sight between your two points. Ideally you need a specialist who uses satellite imagery and specialist desktop planning tools. They will look at building structures, any planning constraints and any planned builds, as well as look at the ease of access to the site for maintenance.
Choose the Correct Technology
The technology will depend on the functionality you require, e.g.: the speed; resilience; availability; redundancy; reporting and diagnostics; traffic management, etc. Choosing the correct technology is essential and there are a number of options out there. If you are sourcing it in-house you need to be acknowledging any limitations that the devices have that may not be evident from the technology vendor’s specifications – variations on performance as a result of the weather, for example.
If you outsource the build of your link it is also pertinent to check that your provider is technology agnostic. This is how you can ensure they will not be bias in their choice and therefore use the right equipment for the job.
Physical Line of Sight
If the desktop line of sight has been carried out to a high standard, this step in planning your microwave link should not throw up many surprises. There are however additional factors that may affect the link’s functionality and so a physical line of sight is still essential. A drive by or ground level survey may be sufficient, however a double ended line of sight survey from height is a likely requirement. You will need a team of engineers qualified to work safely and legally at height. Ideally at this stage an MSV (Multi Skilled Visit) should be carried out, by accessing the cabin (viability having been ascertained at the desktop line of sight stage) and assessing the available rack space, power supply and cable runs.
The Fresnel Zone needs to be clear of any flora and fauna, and should any need to be removed you will require a licensed arborist or tree surgeon to do so. If you have a service provider they will work with the appropriate body to overcome them – for example attending Council general meetings to request permissions.
On occasion you will need to install a link somewhere other than on one of your buildings – and you will require planning permission to install it. An expert in surveying is beneficial for the understanding of the property laws and in finding the most appropriate site for the link. Line of sight is not the only consideration; the site’s readiness needs to be assessed for compatible power and space requirements. Environmental concerns may also need to be addressed. Site rental costs will need to be considered when budgeting for your link – and these may not be included in the managed service price. It helps to outsource to a company who is used to dealing with these issues, as they will often have preferential agreements in place with site landlords.
Once happy that the Fresnel Zone is clear, the link needs to be installed. Access to the site needs to be agreed with the site owners. The installing engineers need to be qualified for the technology, structure access (e.g. IRATA 1, Spainhoist Rope Descent, Rigging, RF awareness, First Aid and Rescue) and accredited by the third party structure owner, if applicable. Testing and commissioning on the equipment needs to be carried out to ensure the link is working in line with the design parameters – a situation facilitated if the design and install of a link is carried out by the same party. Acceptance testing will need to meet the criteria to accord with the appropriate industry British Standards. Performance values also need to be in accordance with those stated in the Ofcom licence.
You can either use separate suppliers for each element or use a company who offers a turnkey service for this.
Maintenance and Management
Your link will have to be monitored around the clock. If you don’t have the ability to do so yourself your managed service provider should have the scale to deliver a Network Operations Centre (NOC) 24/7 that is fully backed up with redundancy built into the NOC systems and follows full Disaster Recovery processes.
Having a managed radio network reduces downtime (for example at MLL Telecom 90% of faults are discovered and fixed without the need for the deployment of a network engineer and typically before our customers notice an issue).
Whether you are self-managing your link, or out-sourcing to a service provider, you can normally manage the balance of your CAPEX versus OPEX spend to what suits you – and with attention to detail with thorough planning a high quality link is attainable.