Telecommunication:Telecommunication means transmission of signal over long distance, such as by telegraph, radio or television.Telecommunication media: used to transport telecommunication signal, types wire pair, coaxial cable, optical fiber and radio link.E1: E1 in its primary rate format transmits 32 channels of 8-bit time slots. An E1 frame therefore has 8 32 = 256 bits. There is no framing bit. Framing alignment is carried out in TS 0. The E1 bit rate to the line is 256 8000 = 2, 048, 000 bps or 2.048 Mbps Framing and basic timing should be distinguished. Framing ensures that the PCM receiver is aligned regarding the beginning (and end) of a bit sequence or frame; timing refers to the synchronization of the receiver clock, specifically, that it is in step with its companion far-end transmit clock. Timing at the receiver is corrected via the incoming 1-to-0 and 0-to-1 transitions. It is mandatory that long periods of no transitions do not occur. E1 frame structure:

Timeslot 0 in the E1 format is the synchronization channel, with a channel bit rate of 64 kbps. Only half of these bits are required for synchronization; the remainder, 32 kbps, is available for on-line error monitoring, for a data channel for remote alarms. These remote alarms tell the system operator about the status of the distant PCM terminal.E1=32*64Kbps=2.048MbpsJourney from pdh to stm

European E1 Digital Hierarchy: The E1 hierarchy is identified in a similar manner as the DS1 hierarchy. E1 (30 voice channels) is the primary multiplex; E2 is the second level and is derived from four E1s. Thus E2 contains 120 equivalent digital voice channels. E3 is the third level and it is derived from four E2 inputs and contains 480 equivalent voice channels. E4 derives from four E3 formations and contains the equivalent of 1920 voice channels. International digital hierarchies are compared in Table 6.2. Table 6.3 provides the basic parameters for the formation of the E2 level in the European digital hierarchy

European standardTotal no. of channelsNo. of usable channels Data rate

E132302.048 Mbps

E2=4E1s1281208.448Mbps

E3=4E2s51248034.368 Mbps

E4=4E3s20481920139.264 Mbps

E5=4E48192565.148 Mbps

SDH: synchronous digital hierarchy Introduction:SDH was a European/CCITT development, whereas SONET was a North American development. They are very similar. One major difference is their initial line rate. STS- 1/OC-1 has an initial line rate of 51.84 Mbps; and SDH level 1 has a bit rate of 155.520 Mbps. These rates are the basic building blocks of each system. SONETs STS-3/OC-3 line rate is the same as SDH STM-1 of 155.520 Mbps. Another difference is in their basic digital line rates. In North America it is at the DS1 or DS3 lines rates; in SDH countries it is at the 2.048, 34, or 139 Mbps rates (see Chapter 6). This has been resolved in the SONET/ SDH environment through the SDH administrative unit (AU) at a 34-Mbps rate. Four such 34-Mbps AUs are nested (i.e., joined) to form the SDH STM-1, the 155-Mbps basic building block. There is an AU3 used with SDH to carry a SONET STS-1 or a DS3 signal. In such a way, a nominal 50-Mbps AU3 can be transported on an STM-1 SDH signal.SDH Standard Bit Rates: The standard SDH bits rates are shown in Table 17.2. ITU-T Rec. G.707 (Ref. 5) states that the first level digital hierarchy shall be 155,520 kbps . . . and . . . higher synchronous digital hierarchy rates shall be obtained as integer multiples of the first level bit rate.Interface and Frame Structure of SDH : figure illustrates the relationship between various multiplexing elements of SDH and shows generic multiplexing structures. Figure 17.17 illustrates one multiplexing example for SDH, where there is direct multiplexing from container-1 using AU-3. Definitions:Synchronous Transport Module (STM) : An STM is the information structure used to support section layer connections in the SDH. It is analogous to STS in the SONET regime. STM consists of information payload and section overhead (SOH) information fields organized in a block frame structure that repeats every 125 ms.The information is suitably conditioned for serial transmission on selected media at a rate that is synchronized to the network. A basic STM (STM-1) is defined at 155,520 kbps. Higher-capacity STMs are formed at rates equivalent to N times multiples of this basic rate. STM capacities for N c 4 and N c 16 are defined, and higher values are under consideration by ITU-T. An STM comprises a single administrative unit group (AUG) together with the SOH. STM-N contains N AUGs together with SOH.

STM-1 FRAME:Synchronous transport module is made up by a matrix of 9 rows and 270 columns

The STM-N signal is multiples of frames consisting of 9 rows with 270 bytes in each row. The order of transmission of information is first from left to right and then from top to bottom. The first 9 bytes in each row are for information and used by SDH system itself. This area is divided into three partsRegenerator section overhead (RSOH)Multiplex section overhead (MSOH)Pointers

SDH Multiplexing:The multiplexing principle in SDH follows these termsMapping (a process used when tributaries are adapted into virtual container (VCs) by adding justification bits and path overhead (POH) information.).Aligning (this process takes place when a pointer is included in a tributary unit (TU) or in an administrative unit (AU), to allow the first byte of the virtual container to be located)Multiplexing (this process is used when multiple lower order path layer signals are adapted into a higher order path signal, or when the higher order path signals are adapted into a multiplex section).

Container: C-n (n c 1 to n c 4): Virtual Container-n (VC-n): A virtual container is the information structure used to support path layer connection in the SDH. It consists of information payload and POH information fields organized in a block frame that repeats every 125 ms or 500 ms. Alignment information to identify VC-n frame start is provided by the server network layer. Two types of virtual container have been identified: 1. Lower-Order Virtual Container-n, VC-n (n = 1, 2). This element comprises a single C-n (n c 1, 2), plus the basic virtual container POH appropriate to that level. 2. Higher-Order Virtual Container-n, to VC-n (n = 3, 4). This element comprises a single C-n (n c 3, 4), an assembly of tributary unit groups (TUG-2s), or an assembly of TU-3s, together with virtual container POH appropriate to that level. Administrative Unit-n (AU-n): An administrative unit is the information structure that provides adaptation between the higher-order path layer and the multiplex section. It consists of an information payload (the higher-order virtual container) and an administrative unit pointer, which indicates the offset of the payload frame start relative to the multiplex section frame start. Two administrative units are defined. The AU-4 consists of a VC-4 plus an administrative unit pointer, which indicates the phase alignment of the VC-4 with respect to the STM-N frame. The AU-3 consists of a VC-3 plus an administrative unit pointer, which indicates the phase alignment of the VC-3 with respect to the STM-N frame. In each case the administrative unit pointer location is fixed with respect to the STM-N frame (Ref. 6). One or more administrative units occupying fixed, defined positions in a STM payload is termed an administrative unit group (AUG). An AUG consists of a homogeneous assembly of AU-3s or an AU-4. Tributary Unit-n (TU-n): A tributary unit is an information structure that provides adaptation between the lower-order path layer and the higher-order path layer. It consists of an information payload (the lower-order virtual container) and a tributary unit pointer, which indicates the offset of the payload frame start relative to the higher-order virtual container frame start. The TU-n (n c 1, 2, 3) consists of a VC-n together with a tributary unit pointer. One or more tributary units occupying fixed, defined positions in a higher-order VC-n payload is termed a tributary unit group (TUG). TUGs are defined in such a way that mixed-capacity payloads made up of different-size tributary units can be constructed to increase flexibility of the transport network. A TUG-2 consists of a homogeneous assembly of identical TU-1s or a TU-2. A TUG-3 consists of a homogeneous assembly of TUG-2s or a TU-3 Container-n (n c 14): A container is the information structure that forms the network synchronous information payload for a virtual container. For each of the defined virtual containers there is a corresponding container. Adaptation functions have been defined for many common network rates into a limited number of standard containers (Refs. 6 and 7). These include standard E-1/DS-1 rates defined in ITU-T Rec. G.702