OFCOM Channel Plans for 7.5GHz and 13GHz

OFCOM Channel Plans for 7.5GHz and 13GHz

Here is a chart showing channel plans for the UK

OFCOM - 7.5GHz & 13GHz
OFCOM – 7.5GHz & 13GHz

Uses & Applications

7.5GHz and 13GHz bands are used for Point to Point (P2P) Microwave Radio Links

Sources of Data and Graphics

All contents (C) OFCOM and taken from:

OfW48 UK Frequency Allocations for Fixed (Point-to-Point) Wireless Services and Scanning Telemetry This document shows the current bands managed by Ofcom that are available for fixed terrestrial (point to point) links and scanning telemetry in the UK.

Technical regulations

The Radio Equipment and Telecommunications Terminal Equipment Directive
99/5/EC (R&TTED) has been implemented in ‘The Radio Equipment and Telecommunications Terminal Equipment Regulations 2000, Statutory
Instrument (SI) 730. In accordance with Articles 4.1 and 7.2 of the R&TTED
the:
• IR2000: The UK Interface Requirement 2000 contains the requirements for the licensing and use of fixed (point-to-point) wireless services in the UK.
• IR2037: The UK Interface Requirement 2037 applies for scanning telemetry services.
• IR2078: The UK Interface Requirement 2078 applies for the 60 GHz band

Notes specific to the frequency charts

The first column describes each available frequency band, represented by a diagram (not to scale). The frequency band limits are listed below the diagram; frequencies below 10 GHz are represented in MHz, while those above 10 GHz are in GHz. The width of each guard band is shown above the diagram, and is always specified in MHz.
The channel arrangements in some bands are staggered, so that the width and position of the guard band vary for different channel spacings. In these cases, a table underneath gives details of the guard bands for different spacings (with all frequencies in MHz).
The first column also includes the title of the relevant international recommendations for each band, produced by the European Conference of Postal and Telecommunications (CEPT) or the International Telecommunication Union (ITU). CEPT recommendations are available at http://www.cept.org/ecc/ and ITU Recommendations at http://www.itu.int.
The final column contains the channel spacing for duplex operation in each frequency band except for bands above 60 GHz. Details of standard systems assigned in the UK are shown in the relevant technical frequency assignment criteria.

For Further Information

For More Information on Microwave Planning, Please Contact Us

OFCOM Channel Plans 450MHz and 1.4GHz

OFCOM Channel Plans for 450MHz and 1.4GHz

Here is a chart showing channel plans for the UK

OFCOM 450MHz & 1.4GHz
OFCOM 450MHz & 1.4GHz

Uses & Applications

450MHz and 1.4GHz bands are used for Point to Point (P2P) Microwave Radio Links

Sources of Data and Graphics

All contents (C) OFCOM and taken from:

OfW48 UK Frequency Allocations for Fixed (Point-to-Point) Wireless Services and Scanning Telemetry This document shows the current bands managed by Ofcom that are available for fixed terrestrial (point to point) links and scanning telemetry in the UK.

Technical regulations

The Radio Equipment and Telecommunications Terminal Equipment Directive
99/5/EC (R&TTED) has been implemented in ‘The Radio Equipment and Telecommunications Terminal Equipment Regulations 2000, Statutory
Instrument (SI) 730. In accordance with Articles 4.1 and 7.2 of the R&TTED
the:
• IR2000: The UK Interface Requirement 2000 contains the requirements for the licensing and use of fixed (point-to-point) wireless services in the UK.
• IR2037: The UK Interface Requirement 2037 applies for scanning telemetry services.
• IR2078: The UK Interface Requirement 2078 applies for the 60 GHz band

Notes specific to the frequency charts

The first column describes each available frequency band, represented by a diagram (not to scale). The frequency band limits are listed below the diagram; frequencies below 10 GHz are represented in MHz, while those above 10 GHz are in GHz. The width of each guard band is shown above the diagram, and is always specified in MHz.
The channel arrangements in some bands are staggered, so that the width and position of the guard band vary for different channel spacings. In these cases, a table underneath gives details of the guard bands for different spacings (with all frequencies in MHz).
The first column also includes the title of the relevant international recommendations for each band, produced by the European Conference of Postal and Telecommunications (CEPT) or the International Telecommunication Union (ITU). CEPT recommendations are available at http://www.cept.org/ecc/ and ITU Recommendations at http://www.itu.int.
The final column contains the channel spacing for duplex operation in each frequency band except for bands above 60 GHz. Details of standard systems assigned in the UK are shown in the relevant technical frequency assignment criteria.

For Further Information

For More Information on Microwave Planning, Please Contact Us

Rain Fade on Microwave Links

Rain Fade on Microwave Links

Microwave Link Rain FadeRain fade refers primarily to the absorption of a microwave radio frequency (RF) signal by atmospheric rain, snow or ice, and losses which are especially prevalent at frequencies above 11 GHz. It also refers to the degradation of a signal caused by the electromagnetic interference of the leading edge of a storm front. Rain fade can be caused by precipitation at the uplink or downlink location. However, it does not need to be raining at a location for it to be affected by rain fade, as the signal may pass through precipitation many miles away, especially if the satellite dish has a low look angle. From 5 to 20 percent of rain fade or satellite signal attenuation may also be caused by rain, snow or ice on the uplink or downlink antenna reflector, radome or feed horn. Rain fade is not limited to satellite uplinks or downlinks, it also can affect terrestrial point to point microwave links (those on the earth’s surface).

Possible ways to overcome the effects of rain fade are site diversity, uplink power control, variable rate encoding, receiving antennas larger (i.e. higher gain) than the required size for normal weather conditions, and hydrophobic coatings.

Two models are generally used for Rain modelling: Crane and ITU.  The ITU model is generally preferred by microwave planners.  A global map of Rain distribution according to the ITU model is shown below:

Global ITU Rain Fade Map for Microwave Link Availability Planning
Global ITU Rain Fade Map for Microwave Link Availability Planning

Used in conjunction with appropriate planning tools, this data can be used to predict the expected Operational Availability (in %) of a microwave link.  Useful Operational Availability figures typically vary from 99.9% (“three nines”) to 99.999%  (“five nines”), and are a function of the overall link budget including frequency band, antenna sizes, modulation, receiver sensitivity and other factors.

Another useful Rain Fade map is shown here, showing the 0.01% annual rainfall exceedance rate:

CableFree ITU-R Rain Fade Map - Global for 0.01% annual rainfall exceedance rate
CableFree ITU-R Rain Fade Map – Global for 0.01% annual rainfall exceedance rate

For more information on this topic, please contact us

MIMO Technology for Microwave Links

An Introduction to MIMO Radio technology

In radio technology, multiple-input and multiple-output, or MIMO , is a method for multiplying the capacity of a radio link using multiple transmit and receive antennas to exploit multipath propagation.

MIMO Radio TechnologyMIMO has become an essential element of wireless communication standards including IEEE 802.11n (Wi-Fi), IEEE 802.11ac (Wi-Fi), HSPA+ (3G), WiMAX (4G), and Long Term Evolution (4G)

Earlier usage of the term “MIMO” referred to the use of multiple antennas at both the transmitter and the receiver. In modern usage, “MIMO” specifically refers to a practical technique for sending and receiving more than one data signal on the same radio channel at the same time via multipath propagation. MIMO is fundamentally different from smart antenna techniques developed to enhance the performance of a single data signal, such as beamforming and diversity.
MIMO can be sub-divided into three main categories, precoding, spatial multiplexing or SM, and diversity coding.

Products using MIMO technology

CableFree products that use MIMO include:

CableFree MIMO radio technology
CableFree MIMO radio technology

Functions of MIMO technology

Precoding is multi-stream beamforming, in the narrowest definition. In more general terms, it is considered to be all spatial processing that occurs at the transmitter. In (single-stream) beamforming, the same signal is emitted from each of the transmit antennas with appropriate phase and gain weighting such that the signal power is maximized at the receiver input. The benefits of beamforming are to increase the received signal gain – by making signals emitted from different antennas add up constructively – and to reduce the multipath fading effect. In line-of-sight propagation, beamforming results in a well-defined directional pattern. However, conventional beams are not a good analogy in cellular networks, which are mainly characterized by multipath propagation. When the receiver has multiple antennas, the transmit beamforming cannot simultaneously maximize the signal level at all of the receive antennas, and precoding with multiple streams is often beneficial. Note that precoding requires knowledge of channel state information (CSI) at the transmitter and the receiver.

Spatial multiplexing requires MIMO antenna configuration. In spatial multiplexing, a high-rate signal is split into multiple lower-rate streams and each stream is transmitted from a different transmit antenna in the same frequency channel. If these signals arrive at the receiver antenna array with sufficiently different spatial signatures and the receiver has accurate CSI, it can separate these streams into (almost) parallel channels. Spatial multiplexing is a very powerful technique for increasing channel capacity at higher signal-to-noise ratios (SNR). The maximum number of spatial streams is limited by the lesser of the number of antennas at the transmitter or receiver. Spatial multiplexing can be used without CSI at the transmitter, but can be combined with precoding if CSI is available. Spatial multiplexing can also be used for simultaneous transmission to multiple receivers, known as space-division multiple access or multi-user MIMO, in which case CSI is required at the transmitter.[32] The scheduling of receivers with different spatial signatures allows good separability.

Diversity Coding techniques are used when there is no channel knowledge at the transmitter. In diversity methods, a single stream (unlike multiple streams in spatial multiplexing) is transmitted, but the signal is coded using techniques called space-time coding. The signal is emitted from each of the transmit antennas with full or near orthogonal coding. Diversity coding exploits the independent fading in the multiple antenna links to enhance signal diversity. Because there is no channel knowledge, there is no beamforming or array gain from diversity coding. Diversity coding can be combined with spatial multiplexing when some channel knowledge is available at the transmitter.

Forms of MIMO

Multi-antenna MIMO (or Single user MIMO) technology has been developed and implemented in some standards, e.g., 802.11n products.

  • SISO/SIMO/MISO are special cases of MIMO
    • Multiple-input and single-output (MISO) is a special case when the receiver has a single antenna.
    • Single-input and multiple-output (SIMO) is a special case when the transmitter has a single antenna.
    • Single-input single-output (SISO) is a conventional radio system where neither the transmitter nor receiver has multiple antenna.
  • Principal single-user MIMO techniques
  • Some limitations
    • The physical antenna spacing is selected to be large; multiple wavelengths at the base station. The antenna separation at the receiver is heavily space-constrained in handsets, though advanced antenna design and algorithm techniques are under discussion.