Telecommunication

Mobile station (MS) • The Mobile Station is the interface between the user and the network. The MS consists of two independent parts:  Subscriber Identity Module (SIM) card  Mobile equipment (ME). Base transceiver station (BTS) • A BTS acts as the interface between MS’s and the network, by providing radio coverage functions from their antennae to provide the coverage area for one cell. • Converts the GSM radio signals into a format that can be recognized by the BSC • Ciphering using the ciphering key • Channel coding and interleaving • Modulation and demodulation. • Records and passes to the BSC the Signal strength measurements Base station controller (BSC) • The BSC is the central node within a BSS and co-ordinates the actions of Base Stations. The BSC controls a major part of the radio network • Hand over calculations. • Power control calculations. • Supervises the transmission network and the operation of each BTS Mobile switching ce...

We will now start the course by defining the characteristics of the radio wave. The first characteristic is the frequency. Frequency By frequency we mean how often the two poles in an electric circuit or the electrical field in a radio wave change polarity. In every day life we meet this for example when connecting a device to a mains power outlet. The sinusoid curve in the slide is describing one complete oscillation. Half of the time it is positive and half of the time negative. Frequency is measured in the unit Hertz and is the number of times per second which the one oscillation curve is repeated. If a complete oscillation happens one time per second this is defined as one Hertz. In ordinary mains power the curve shape is repeated 50, in some countries 60, times per second. We say that the mains frequency is 50 Hertz or 60 Hertz. In radio communication much higher frequencies are used, actually up to several tens of thousand million hertz. To descr...

Let’s start with the Plesiochronous Digital Hierarchy, PDH Many years ago there was a need to make telephone calls digital. Since our speech is analog, it has to be converted into a digital bit stream. To do this, samples of the analog signal are taken and represented as numbers. Expressed in binary digits, every sample uses 8 bits. To gather all information in a normal conversation, phone services normally use 8000 samples per second. This way, we need a data stream of 64 kbit/s to transport one telephone call. That is the reason why 64kbit/s data streams are frequently used in telecommunications. So you have a 64 kbit/s data stream that carries one phone call. The transport medium that you have available is usually a cable or a microwave link with a much higher data rate, so you can transport many phone calls. To combine many slow streams of data into one faster one, you use a multiplexer. The multiplexer puts data into so-called frames that are se...

In order to separate different transmitters, frequency bands are subdivided into sections called channels. In this chapter we will see which main frequency bands there are for microwave transmission and how they are divided into channels. Remember, this assignment is done by ITU-R and the World Radio communication Conference. The bands which are indicated by blue color are the traditional bands which have been in use for long time. They are quite heavily used today. In some countries it can be hard to find free spectrum for new deployments in these bands. Because of this, new bands have been assigned. Quite recently the bands 42, 60 and 80 gigahertz were opened by the World Radio communication Conference. The 50, 52 and 55 gigahertz bands are assigned for future microwave deployments… …and the 95 gigahertz band is currently under study by the standardization bodies for future deployment as well. The ITU-R publishes one recommendation document per fre...

To allow the usage of microwave transmission equipment, all European and many non-European national authorities require that the equipment must meet the ETSI standards. ETSI standards are published in different series. Here are two examples; EN 302 217 and EN 300 019. Series EN 302 217 is the main standard for point to point microwave transmission equipment. It consists currently of six different publications and states technical specifications for radio equipment and antennas. Series EN 300 019 is a more generic standard for electronic equipment which specifies under what environmental conditions the equipment shall be operational. This is specified for equipment intended for indoor and outdoor use and in operation, storage and transportation. ETSI standards are available for download from the ETSI web site, etsi.org. There are several additional standardization institutes which are relevant to telecommunications equipment. ITU-T, the Telecommunication ...

The Electronic Communications Committee, abbreviated ECC  is a European organization for spectrum management. It is a part of the European Conference of Postal and Telecommunications Administrations, CEPT. As the name of the mother organization indicates ECC mainly consists of national frequency authorities. As within ITU-R the work within ECC is organized in work groups. Each work group concentrates on a specific topic. Of most interest for microwave radio links is the Spectrum Engineering work group 19, SE19. , This group deals with spectrum management for fixed services, including microwave radio links. To put it simply, ECC SE19 specifies how to apply the ITU-R spectrum recommendations for fixed services in Europe. For example specification of channel patterns for different channel bandwidths. Members of the ECC with the right to vote are the European national frequency regulation authorities and network operators. Equipment manufacturers, like Eri...

Microwave Transmission Technology Fundamentals course about frequency regulation and equipment standards. After the course you will have a basic understanding of the following: International Spectrum Recommendations and Equipment Standards applicable to Microwave Systems The role of National Regulation Authorities Spectrum Licenses and the License Application Process Radio Channels To navigate in the course and jump between pages use the Menu button. The Audio button allows switching the audio on or off and to read the subtitles. The help button will give this navigation information in writing. The Notes button gives access to a personal notes field. Click the replay button to view the animation again and the play/pause button to start or stop the animation This frequency range is the natural resource available for radio communication. To make the most of this limited resource it is necessary to regulate and harmonize the use of it. This regulation ca...

Long Distance Communications Telecommunication is the process of long distance communications. Early telecommunications involved smoke, flags, drums, and other such methods to relay messages and information. Telegraph : The first wire line communications was the telegraph. Invented in  the mid 19 th century, it opened a new era in long-distance telecommunication. Telephone : When we talk over the telephone, our voice is converted to an  electronic signal by the microphone in handset. This signal is then transmitted  over telephone wires Telephone Networks Early Switching Devices:  Switches are devices that cause a connection between two transmitting/receiving devices. Modern Switching Devices : Today many different types of automated switches are used which make it possible for fast placement of calls. Types of telephones: - Fixed (PSTN) telephones - Cordless Telephones - Mobile Telephones Modes OF Transmission in wireless:  1-  Simple...