Sub 6 Unlicensed & Licensed

What does Sub 6GHz Licensed and Unlicensed mean?

Several vendors and operators use this term: Find out what “Sub 6” means in practice.

Sub 6GHz Unlicensed & Licensed Links
Sub 6GHz Unlicensed & Licensed Links

What is Sub 6 ?

“Sub 6” means frequencies below 6GHz.   Though frequencies from 1GHz up to 6GHz are still classified as microwave frequencies, they are often referred to “radio links”, “microwave links”, “microwave radio links” with these terms used interchangeably.

Why Consider Sub 6GHz?

Typically links below 6GHz are used for longer point-to-point links, or point-to-multipoint links for last-mile access to customers.  Frequencies below 6GHz do not suffer significant rain fade.  In addition, these lower frequencies can be used for Non-Line-of-Sight Links, in cases where there is no direct Line of Sight between the locations that require connection.  The radio propagation characteristics of lower-frequency bands make them ideal for urban areas where radio signals may reflect from buildings and other man-made objects, and can – within limitations – penetrate walls, brickwork and concrete structures.

What does Unlicensed and Licensed mean?

The term Unlicensed in radio technology includes commonly used bands which can be used in many countries without need for a frequency license, such as 2.4GHz and 5.x GHz bands including 5.2GHz, 5.4GHz and 5.8GHz.  Please note that in a few countries these frequencies still require licenses, or are not usable by private users.
Unlicensed frequencies have the benefit of not requiring a license to operate (typically, licenses have an annual fee, and are issued by a national regulator or state owned telecom operator).  However, unlicensed links can be interfered with by other users, which can cause reduced throughput or complete link outage.  Such interference is generally heavier in high density population areas and cities, where 100’s or 1000’s of radios may be competing for the same spectrum in a given region.

Conversely, licensed operation means that the equipment user has to obtain a frequency license before using the band.  This can be available on a per-link basis, in which case the regulator allocates specific frequencies for a particular link, holding a central database of all links, or in the case of mobile operator networks, a country-wide license within which the operator self-coordinates the allocation of frequencies and coverage.
The lack of predictability in unlicensed bands is the main reason that operators prefer licensed bands for operation, despite the additional costs of licenses required to operate.

Single Carrier and OFDM Modulation

In the “Sub-6” bands 1-6GHz, a range of Single Carrier, OFDM and OFDM-A technology solutions are available.  OFDM and OFDM-A use multiple subcarriers, and can use the properties of this modulation to overcome multipath fading and reflections from hard surfaces present in dense city areas.  Conversely, Single Carrier radios use dense modulation with high symbol rates on a single radio carrier.  This can give high spectral efficiency and data rates, but limited ability to cope with reflected signals, and hence worse performance in non-LOS situations.

Line of Sight, Non-Line-of-Sight, Near-Line-of-Sight and Radio Propagation

OFDM modulation is generally used in Sub-6 radios and is more suitable to rapidly fading and reflected signals, hence for mobility and non-line-of-sight (non-LOS, NLOS, Near-LOS, nLOS) applications.  Generally, the lower the frequency band, the better non-LOS characteristics it has, improving range and in-building coverage and penetration through windows, walls, brickwork and stone.

4G & 5G Mobile and Fixed Networks

4G 5G Wireless Network Sub-6GHz
4G & 5G Wireless Networks operate in Sub-6GHz bands

Both 4G and 5G technologies defined by the 3GPP use OFDM and OFDM-A technology in the sub-6GHz bands to deliver high speed fixed and mobile data services.  These classify as “sub 6” but are rarely referred to as such.  MIMO (Multiple Input, Multiple Output) technology is added on top of OFDM to increase throughput still higher.  More recently, 5G includes “millimeter wave” bands above 20GHz to add still higher speed services and overcome congestion in lower frequency bands.  It is envisaged that users could roam seamlessly between regions with “Sub 6” and “millimeter wave” coverage with suitable handsets or terminal devices.

Managing the Finite Spectrum Available in 1-6GHz

An obvious downside of Sub-6GHz is the limited spectrum available.  There is just 5GHz of spectrum available between 1-6GHz which has to be allocated between multiple applications for Telecom Operators, Government and Private networks, utilising signals that can travel 10-50km or more and therefore potentially interfering with each other if inadequately managed.  Though most applications are terrestrial, the bands include space for ground-satellite services which again have to avoid interference.  Increasingly, frequency regulation is a global issue with international roaming, and huge spectrum demands and pressure on spectrum from Mobile Network Operators who face ever increasing demands for mobile data users worldwide.  To meet this demand, spectrum is continually re-farmed and re-allocated between older 2G and 3G services to 4G and 5G services which are capable of delivering higher capacity services.  Legacy frequency allocations to Government and Military applications are often released for lease to such operators also.

For more information

Please Contact Us

 

Point to Point Microwave Link

Wireless Point-to-Point Microwave Bridge Links

Microwave Point to Point can be tailored to suit the needs and requirements of all applications

CableFree FOR3 Point to Point Microwave P2P PTP Installed in the Middle East
CableFree FOR3 Microwave P2P link Installed in the Middle East

Point to Point links are transparent, acting as an extension of the Ethernet backbone or segment. Licensed Microwave is fully compatible with the Ethernet standard, and supports all Ethernet functionality and applications.

Point to Point Microwave has been the connectivity choice for Telecom carriers, corporate organisations and Government authorities for many of years. Point to Point Radio offers high speeds, high availability over large connection distances, it can be relied upon to carry voice and data traffic in a number of bandwidth-intensive applications, such as:

  • Connecting locations that are unavailable or in poor Broadband areas
  • Private data Networks (WANs, LANs, etc.)
  • Utility Networks (Railways, Pipelines, etc.)
  • Last Mile access for Corporate, SMEs and Local Government
  • Connecting buildings and facilities over large distances

Microwave P2P – Ideal replacement for Fibre Optics and Leased Lines

CableFree Microwave Link using 30cm antenna benefits from ACM giving longer reach and higher availability
CableFree Microwave Link using 30cm antenna benefits from ACM giving longer reach and higher availability

Point to point wireless is the ideal alternative for business communication between two buildings or sites where wired connection is either impossible, costly or impractical. Point to point Ethernet bridge link facilitates a wireless data connection between two or more networks or buildings across distances up to 100 Kilometres and at speeds up to 1Gbps.

Point to point wireless links are an excellent alternative to fibre optics and leased lines, providing businesses with fibre-like speeds for high-speed data, voice and video transfer between business locations.

Asking an expert team to assist with your point to point wireless requirement will ensure you get a well-designed Microwave Link solution and expertise to help you and your business to benefit from high-capacity, low-latency, long distance wireless data transfer. Quality design, installation and support teams are always on-hand to ensure that your project is delivered on time and to the highest standards.

Long Distance Point to Point WiFi

WiFi is sometimes used for outdoor links – with directional antennas – despite the WiFi radio protocol not being optimised for long distance links.  Instead, customised airside protocols on dedicated outdoor radios are far better for security, throughput and link stability.

Point to Point Ethernet bridge

CableFree Microwave Point to Point Radio Links P2P PTP
CableFree Microwave Point to Point Radio Links

A point to point Ethernet bridge link can benefit your business through the elimination of leasing lines or subscription based systems with no loss in performance. Providing highly reliable connections, point to point wireless offers a far lower total cost of ownership and has the versatility of deployment within rural, metropolitan and residential environments.

Whether you are looking to achieve high-speed business networking or to provide wireless backhaul for CCTV connectivity, point to point bridges are the best option.

Where line-of-sight (LOS) exists between two points, point to point bridge pairs can be set-up and installed with the minimum of disruption to your business and can usually be completed within a single day. The ease of install and the resilience to harsh weather conditions make point to point bridge links a viable fibre alternative.

Operating in both licensed and unlicensed spectrums, our point to point solutions ensure that your business has the network uptime and performance for mission-critical data transfer – our links offer 99.999% uptime.

Broadcasting, construction or military environments often require temporary wireless connections. The simplicity of point to point WiFi makes it the perfect solution where temporary wireless connection is required between two points.

Licensed or Unlicensed Point to Point Microwave Links

When selecting the correct point to point wireless link for your business, there are a number of important decisions to be made to ensure that the final outcome meets the initial expectations. Point to point microwave links can be either licenced or unlicensed, both of which have a specific set of capabilities, advantages and disadvantages, the main one being their relative susceptibility to interference-free operation.

For businesses seeking a wireless backhaul which will serve as a direct replacement for leased lines, licensed microwave links – which operate within the ‘licensed’ 4-42GHz bands, – will provide superior bandwidth availability, speed and the interference protection necessary.

Although offering no guaranteed interference protection, unlicensed microwave links which operate in the ‘unlicensed’ frequency bands, either typically in 2.4 and 5GHz bands, in some regions 17GHz and 24GHz, and 58GHz/60GHz (V-band), can provide a more cost effective option as they eliminate any additional costs and can be rapidly deployed.

For Further Information

For More Information on Microwave Planning, Please Contact Us

Microwave ODU

Microwave ODU (Outdoor Unit)

The term ODU is used in Split-Mount Microwave systems where an Indoor Unit (IDU) is typically mounted in an indoor location (or weatherproof shelter) connected via a coaxial cable to the ODU which is mounted on a rooftop or tower top location.

CableFree Microwave ODU
CableFree Microwave ODU

Often the ODU is direct mounted to a microwave antenna using “Slip fit” waveguide connection.  In some cases, a Flexible Waveguide jumper is used to connect from the ODU to the antenna.

ODU functions

The ODU converts data from the IDU into an RF signal for transmission. It also converts the RF signal from the far end to suitable data to transmit to the IDU. ODUs are weatherproofed units that are mounted on top of a tower either directly connected to a microwave antenna or connected to it through a wave guide.

Generally, Microwave ODUs designed for full duplex operation, with separate signals for transmit and receive.  On the airside interface this corresponds to a “pair” of frequencies, one for transmit, the other for receive.  This is known as “FDD” (Frequency Division Duplexing)

ODU Power and data signals

The ODU receives its power and the data signals from the IDU through a single coaxial cable. ODU parameters are configured and monitored through the IDU.  The DC power, transmit signal, receive signal and some command/control telemetry signals are all combined onto the single coaxial cable.  This use of a single cable is designed to reduce cost and time of installation.

ODu Frequency bands and sub-bands

Each ODU is designed to operate over a predefined frequency sub-band. For example 21.2 – 23.6GHz for a 23GHz system, 17.7 – 19.7GHz for a 18GHz system and 24.5 – 26.5GHz for a 26GHz system as for ODUs.    The sub-band is set in hardware (filters, diplexer) at time of manufacture and cannot be changed in the field.

1+0, 1+1, 2+0 Deployments

Microwave ODUs can be deployed in various configurations.

Microwave ODU in 1+0 Configuration with Antenna
Microwave ODU in 1+0 Configuration with Antenna

The most common is 1+0 which has a single ODU, generally connected directly to the microwave antenna.  1+0 means “unprotected” in that there is no resilience or backup equipment or path.

 

 

 

Two Microwave ODUs in 1+1 HSB or 2+0 configuration with Coupler and Antenna
Two Microwave ODUs in 1+1 HSB or 2+0 configuration with Coupler and Antenna

For resilient networks there are several different configurations.  1+1 in “Hot Standby” is common and typically has a pair of ODUs (one active, one standby) connected via a Microwave Coupler to the antenna.  There is typically a 3dB or 6dB loss in the coupler which splits the power either equally or unequally between the main and standby path.

Other resilient configurations are 1+1 SD (Space Diversity, using separate antennas, one ODU on each) and 1+1 FD (Frequency Diversity)

The other non-resilient configuration is 2+0 which has two ODUs connected to a single antenna via a coupler.  The hardware configuration is identical to 1+1 FD, but the ODUs carry separate signals to increase the overall capacity.

Grounding & Surge Protection

Suitable ground wire should be connected to the ODU ground lug to an appropriate ground point on the antenna mounting or tower for lightning protection.  This grounding is essential to avoid damage due to electrical storms.

In-line Surge Suppressors are used to protect the ODU and IDU from surges that could travel down the cable in the case of extreme surges caused by lightning

The specification of a typical Microwave ODU is shown below.

Typical ODU Features and Specifications:

  • 4-42GHz frequency bands available
  • Fully synthesized design
  • 3.5-56MHz RF channel bandwidths
  • Supports QPSK and 16 to 1024 QAM.  Some ODUs may support 2048QAM
  • Standard and high power options
  • High MTBF, greater than 92.000 hours
  • Software controlled ODU functions
  • Designed to meet FCC, ETSI and CE safety and emission standards
  • Supports popular ITU-R standards and frequency recommendations
  • Software configurable microcontroller for ODU monitor and control settings
  • Low noise figure, low phase noise and high linearity
  • Compact and lightweight design
  • Very high frequency stability +/-2.5 ppm
  • Wide operating temperature range: -40°C to +65°C

For Further information

For More Information about Microwave ODUs, we will be delighted to answer your questions. Please Contact Us

Unlicensed Wireless Links

What is an Unlicensed Microwave link?

Unlicensed and light licence wireless links is the most cost effective of all links and can be deployed in a matter of days. Currently in most countries there are a few unlicensed ISM-band frequencies that are used for point to point links and a few light licensed frequencies that provide interference free operation.

What is a Light Licensed microwave link?

Regional regulators (typically, in each country) are responsible for Spectrum Management of the Radio Spectrum.  This naturally varies in each country due to different history of usage and allocation.

A Light License is where the licensee pays a small licence fee to register his/her radio link with regional regulators such as OFCOM  (UK).

The regulator (such as OFCOM in the UK) use the licence to inform other potential users of the spectrum that there is already a radio link or links in the area when they register their own link prior to deployment. This information is also used to resolve disputes should interference arise.

Frequencies used

Depending on which country you are in, these can include:

  • Licence free spectrum are the 5Ghz, 24Ghz, and 60GHz frequencies
  • Light licence spectrum operate in the 64-66GHz and 70/80GHz

Why consider unlicensed or light license links?

  • Low density areas not suffering from RF interference
  • Budget constraints
  • Non-critical data transmission

When are licensed links mostly used?

  • Organisations looking to create a LAN across multiple buildings on the same site
  • Organisations looking to reduce the cost of existing leased lines
  • In low density areas where RF interference is low or free

When to consider opting for a licenced over unlicensed?

  • High density areas suffering from RF interference
  • Mission-critical data transmission

Is unlicensed or light licenced microwave right for you?

If you are looking for the simple answer, please contact Wireless Excellence for details. Our very experienced team are happy to discuss your requirements and advise on the best solution whatever your needs.