TE303-LN-3.ppt - Terrestrial telecommunication infrastructures Terrestrial means of relating to earth or its inhabitants Examples of terrestrial

TE303-LN-3.ppt - Terrestrial telecommunication...

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Unformatted text preview: Terrestrial telecommunication infrastructures Terrestrial, means of relating to earth or its inhabitants. Examples of terrestrial telecommunication infrastructures include but are not limited to: paging systems (POCSAG, FLEX, etc.) trunked radio systems (analogue trunked radio system, iDEN, TETRA) cellular radio systems (AMPS, TACS, IS-95, GSM, EDGE, WCDMA, CDMA2000, etc.); wireless broadband systems (LMDS, MMDS) satellite-based mobile communication systems (Iridium, Globalstar, Teledesic). Paging system A system consisting of personal paging receivers, radio transmitters, and an encoding device, designed to alert an individual, or group of individuals, and deliver a short message Cordless Telephones PSTN Cordless Phone Base unit A cordless phone is a model of telephone which replaces the coiled wire between the handset and base unit with wireless radio technology. The land line connection from the phone company is still fed into the base unit, but the powered handset transmits and receives radio signals in place of traditional electronic pulses. As long as the base antenna can receive transmissions from the handset, the user is free to roam a few hundred feet without being Tethered to a coiled wire. Cellular radio systems Functional network elements User Equipment (UE) interfaces with user and radio interface Radio Access Network: handles all radio-related functionality. Core Network switches and routes calls and data connections to external networks Core Network GSM Architecture Access Network PSTN GMSC BSC Internet cloud MSC BTS/RBS BSC databases BSC BTS MS BTS MTN NETWORK ACHITECTURE Accra IA Site BSC7 BSC8 BSC10 Kumasi-Kwadaso Site MSC10 MSC5 MSC8 MSC6 Accra Graphic Rd. Site BSC2 BSC12 PSTN & Other PLMN MSC2 Kumasi Site GMSC2 Accra IA BSC4 MSC7 GMSC1 Accra Graphic Rd. BSC9 TDM (Transit) MSC-S11 GMSC3 Kumasi BSC13 MSC3 BSC6 MGW1 MSC4 Tema MSC9 MGW3 BSC16 BSC14 MSC12 BSC5 BSC11 BSC15 MSC-S14 Cape Coast Site Tamale Site MGW5 MSC-S13 MGW2 BSC3 MGW4 BSC17 MSC1 BSC1 BSC18 Position of RNC in WCDMA System UTRAN UE Uu CN MSC Server Iu Iu-CS RNC Iub NodeB b Iu Iur NodeB Iu-PS PS Iub NodeB RNC Iu-BC CBC GSM SYSTEM INTERFACES Um interface or Air interface is the interface between the GSM mobile station and the GSM Base station. The Air interface (RF Interface) uses the TDMA technique to transmit and receive traffic and signaling information between the BTS and MS. The A-bis interface is responsible for transmitting traffic and signaling information between the BSC and the BTS. A-interface provides two distinct types of information, signaling and traffic, between the MSC and the BSC. GSM Network Architecture GSM NETWORK COMPONENTS The GSM network is divided into three systems. Each of these systems are comprised of a number of functional units which are individual components of the mobile network. The GSM network can be divided into following broad parts. The Base Station Subsystem (BSS) The Network Switching Subsystem (NSS) The Operation Support Subsystem (OSS) Abbreviations The SS is responsible for performing call processing and subscriber related functions. It includes the following functional units: • Mobile services Switching Center (MSC) • Home Location Register (HLR) • Visitor Location Register (VLR) • AUthentication Center (AUC) • Equipment Identity Register (EIR) The BSS performs all the radio-related functions. The BSS is comprised of the following functional units: • Base Station Controller (BSC) • Base Transceiver Station (BTS) The OMC performs all the operation and maintenance tasks for the network such as monitoring network traffic and network alarms. The OMC has access to both the SS and the BSS. MSs do not belong to any of these systems SWITCHING SYSTEM (SS) COMPONENTS The MSC performs the telephony switching functions for the mobile network. It controls calls to and from other telephony and data systems, such as the Public Switched Telephone Network (PSTN), Integrated Services Digital Network (ISDN),public data networks, private networks and other mobile networks. Gateway Functionality Gateway functionality enables an MSC to interrogate a network's HLR in order to route a call to a Mobile Station. Such an MSC is called a Gateway MSC (GMSC). For example, if a person connected to the PSTN wants to make a call to a GSM mobile subscriber, then the PSTN exchange will access the GSM network by first connecting the call to a GMSC. The same is true of a call from an MS to another MS. Any MSC in the mobile network can function as a gateway by integration of the appropriate software. The Network Switching Subsystem (NSS) The main role is to manage the communications between MS users and other users, such as ISDN users, Fixed telephony users etc. It includes databases needed in other to store information about the subscribers and to manage their mobility. MOBILE SWITCHING CENTER (MSC) It is the central components of the NSS. The MSC preforms the switching functions of the network. It also provides connection to other network. Perform the routing path search, signal routing and service feature processing. Associated with MSC is a functional unit enabling the networking of GSM network and the fixed network (PSTN, ISDN) Gateway MSC GMSC is a node interconnecting two networks. It is the interface between the mobile cellular networks and the PSTN. GMSC is in charge of routing calls from fixed network towards a GSM user. GMSC is often implemented in the same machines MSC. GMSC pass the voice traffic between the fixed network and the mobile network. International switching center (ISC) is used to connect the mobile networks to the international networks Home Location Register The HLR is a centralized network database that stores and manages all mobile subscriptions belonging to a specific operator. It acts as a permanent store for a person's subscription information until that subscription is canceled. The information stored includes: • Subscriber identity • Subscriber supplementary services • Subscriber location information • Subscriber authentication information The HLR can be implemented in the same network node as the MSC or as a stand-alone database. If the capacity of a HLR is exceeded by the number of subscribers, additional HLRs may be added. Visitor Location Register (VLR) The VLR database contains information about all the mobile subscribers currently located in an MSC service area. Thus, there is one VLR for each MSC in a network. The VLR temporarily stores subscription information so that the MSC can service all the subscribers currently visiting that MSC service area. The VLR can be regarded as a distributed HLR as it holds a copy of the HLR information stored about the subscriber. When a subscriber roams into a new MSC service area, the VLR connected to that MSC requests information about the subscriber from the subscriber's HLR. The HLR sends a copy of the information to the VLR and updates its own location information. When the subscriber makes a call, the VLR will already have the information required for call set-up. AUthentication Center (AUC) The main function of the AUC is to authenticate the subscribers attempting to use a network. In this way, it is used to protect network operators against fraud. The AUC is a database connected to the HLR which provides it with the authentication parameters and ciphering keys used to ensure network security. Equipment Identity Register (EIR) The EIR is a database containing mobile equipment identity information which helps to block calls from stolen, unauthorized, or defective MSs. It should be noted that due to subscriberequipment separation in GSM, the barring of MS equipment does not result in automatic barring of a subscriber. Base Station Subsystem The BSS connect the MS and the NSS. It is in charge of the transmission and reception. The BSS can be divided into two The Base Transceiver station (BTS) The Base station controller (BSC) The Base Transceiver station (BTS) A BTS is usually placed in the center of the cell. It’s transmitting power define the size of the cell Each BTS has between one and sixteen transceivers depending on the density of the users in the cell. Base Transceiver Station (BTS) Terminating the radio links with the mobile station. A group of BTSs are controlled by a BSC. RF resources such as frequency assignments, sector separation, transmit power control. Typically equated to the physical site of the wireless network. 3-cell BTS configuration is most common (max. up to 6 cell BTS). BTS connects to BSC through un-channelized T1/E1 facilities or direct cables in co-located equipment (Abis) RBS/BTS Base Station Controller (BSC) Call processing Radio resource management Mobility management Transmission facilities management SDU (Selection/distribution unit) : when soft handoff, this selects the best incoming air interface data frame from the receivers. Vocoder BSC-BTS : Abis a set of trunks : backhaul BSC-MSC : A1/A2/A5 a set of trunks : fronthaul Base Station Controller (BSC) A number of BSCs may be controlled by each MSC. BSC principally in charge of frequency hopping, control of the radio frequency power levels of the BTSs. Operation and Maintenance Center (OMC) An OMC is a computerized monitoring center which is connected to other network components such as MSCs and BSCs via X.25 data network links. In the OMC, staff are presented with information about the status of the network and can monitor and control a variety of system parameters. There may be one or several OMCs within a network depending on the network size. Network Management Center (NMC) Centralized control of a network is done at a Network NMC. Only one NMC is required for a network and this controls the subordinate OMCs. The advantage of this hierarchical approach is that staff at the NMC can concentrate on long term system-wide issues, whereas local personnel at each OMC can concentrate on short term, regional issues. OMC and NMC functionality can be combined in the same physical network node or implemented at different locations. Cables Distribution Figure (X.25 data network links) NMC VIEW MOBILE STATION (MS) An MS is used by a mobile subscriber to communicate with the mobile network. Several types of MSs exist, each allowing the subscriber to make and receive calls. Manufacturers of MSs offer a variety of designs and features to meet the needs of different markets. The range or coverage area of an MS depends on the output power of the MS. Different types of MSs have different output power capabilities and consequently different ranges. For example, hand-held MSs have a lower output power and shorter range than car-installed MSs with a roof mounted antenna. GSM MSs consist of: • A mobile terminal • A Subscriber Identity Module (SIM) The Terminal There are different types of terminals distinguished principally by their power and application The fixed terminals are the ones install in cars. The max allowed out power is 20w. GSM portable terminals can also installed in vehicles. The max allowed out power is 8w. The handheld terminals have experienced the biggest success, thanks to their weight and volume, which are continually decreasing. This terminals can emit up to 2W. The evolution of technologies allow decreases the max allowed power to 0.8W The SIM The SIM is a smart card that identify the terminal. By inserting the sim card into the terminal the user can have access to all subscribed services. Without the sim card the Terminal is not operational. The SIM card is protected by four digits, Personal identification number (PIN). In other to identify the subscriber to the system, the SIM card contains some parameters of the user such international mobile subscriber identity (IMSI). Another advantage of the SIM card is the mobility of the users, in fact the only element that personalizes a terminal is the SIM card. SIM achieved separation of user mobility from equipment mobility. This enabled international roaming independent to the mobile equipment and the network technology. SIM card store short messages, charging information and list of numbers for fast dialing and all cryptographic algorithms. Example: mobile phone • Typical phone has a microcontroller (SIM card) with a small program – Drive GUI – Control devices (keypad, microphone, a/d, dsp, decoder) Channels in GSM The logical channels are divided into two categories: Traffic channel (TCH): used in transmitting user payload (speech, data). TCH do not carry any control information. Communication can be circuit switched of packet switched Signaling Channel (BCCH): Broadcast control channel This is a unidirectional point to multipoint channel between MS and BS. The following kind of information is sent: Radio channel config.(current and nearby cell) Synchronization (Frequency and frame numbering) Registration identifiers Synchronization channel (SCH): Broadcast info to identify BS and for frame synchronization of the MS. Forward link Channels The forward link channel uses four types of channels to transmit voice and control data to the mobile. Pilot Sync Paging Traffic Pilot Channels BTS constantly transmit Pilot channels The MS uses the pilot signal to acquire the system. It then uses the pilot signal to monitor and adjust the power needed in other to transmit back to the BTS. Sync BTS constantly transmit over the sync channels so that the MS can synchronize with the BTS. It provides the mobile with the system time and identification number of the cell site. The mobile ignore the sync channel after it has synchronized. Paging channels Paging channel transmit overhead information such as commands, pages to the mobile and traffic channel assignment during call set up. The mobile ignore the paging channel after a traffic channel has been established. Paging, sync and pilot channels are referred to as FORWARD CONTROL CHANNEL (FCC) Traffic Channels About sixty-one forward traffic channels are used to send both voice and overhead control data during a call. Once the call is completed, the mobile tunes back into the paging channel for commands and pages. Traffic channels is known as FORWARD VOICE CHANNEL (FVC) Reverse link channel The channels provide from the mobile to the Base station. Uses two types of channels to transmit voice and control data to the BTS. Access Traffic Access Channel (RCC) The mobile uses the access channel when not assigned to a traffic. Uses to Register with the network Originates calls Response to pages and commands from the base station. Transmit overhead messages to the Base station. Reverse link Traffic Channels (RVC) The reverse traffic channel is only used when there is call Transmit voice data to the BTS Transmit overhead control information to the BTS. Forward and Reverse Channels To establish a call between the BS and the MS we need channels. Forward Voice Channel (FVC): Used for voice transmission from BS to MS. Reverse Voice Channel (RVC): Used for voice transmission from MS to BS. Forward Control Channel (FCC): Used for initiating a call from the BS to MS Reverse Control Channel (RCC): Used for initiating a call from the MS to BS. FCC and RCC are called setup channels and are used as overheads Call processing stages Initialization mode Idle mode Access mode Traffic mode Initialization and idle mode During initialization mode, the mobile acquire the system via the pilot channel. Synchronizes with the system via the sync channel. Idle mode: MS not involve in a call but must stay in communication with the BTS, this is done over the access and paging channels. The mobile obtain overhead info via the paging channels. Access mode The MS Accesses the network via the access channel during call originating The Access channel and Paging channel carry the require call set up communication between the MS and the BTS until the traffic channel is established. Call from PSTN to Mobile Phone When a PSTN subscriber calls a mobile user, the MSC dispatch the request to all base stations(BS). The mobile identification number(MIN) is broadcast as a paging message over the forward control channels (FCC). The MS receives the paging message sent by the BS and respond by identify itself over the reverse control channel(RCC). The BS relays the ACK sent by the MS and informs the MSC of the handshake. MSC instruct the BS to move the call to an unused voice channel within the cell. The BS signals the MS to change frequencies to an unused forward and reverse voice channel pair. An alert is transmitted over the FVC to instruct the MS to ring. MSC adjusts the Tx pwr of the MS and change the channel in order to maintain call quality during movement in and out of range of each BS. This is called HANDOFF. Call from Mobile Phone to PSTN When a MS originates a call, initiation request is sent on the RCC with MIN, electronic serial number (ESN) and the telephone number of the called party. Also transmit station class mark (SCM) to indicate max power level to be used. The BS received this data and send it to the MSC for validation. MSC instruct FCC of originating BS to move MS to a pair of voice channels via a page msg. BS receives page data and matches MIN and move to voice channel. MSC connect to the called party on PSTN and begin voice Tx/Rx Roaming Mobile Phone This allows subscriber’s to operate in service areas other than the one from which service is subscribed. When a mobile enters a city or geographic area that is different from it home service area, it is registered as a roamer in the new service area. This is accomplished by: MSC issues a global command over each FCC in the system at all time, asking for the all mobile which are previously unregistered to report their MIN and ESN over the RCC. New unregistered MS in the system periodically report back their subscriber info upon receiving the registration request, MSC then uses the MIN/ESN data to request billing status from the home location register (HLR). MSC register the subscriber if the MS has authorization for billing purposes. Once registered, roaming MS are allowed to Tx/Rx and the billing is routed automatically to the subscriber’s home service provider. HANDOFF When a mobile moves into a different cell while a call is in progress the MSC automatically transfers the call to a new channel belonging to the new BS. The handoff operation involves identifying a new BS and the allocation of voice and control channels associated with the new BS. VERIFY YOR MOBILE PHONES QUALITY USING IMEI MOBILE TRICK Find IMEI ID of your mobile. Dial *#06#. A 15-digit number will be displayed on the screen. This is your mobile IMEI ID. Here is a sample IMEI number : 2 4 5 6 6 1 0 2 3 0 7 2 4 0 9 How to Check Cell Phones Quality Using IMEI Look on the 7th and 8th digit. These two digits ensure your cell phone quality. 7th and 8th Value Made in Quality 02 or 20 Emirates poor 08 or 80 Germany fair 01 or 10 Finland high 00 Original Mobile Factory best 03/30 or 04/40 China average 05 or 50 Finland USA or Brazil good 06 or 60 China, Mexico or Hong Kong good 13 Azerbaijan poor, cause heath hazards Any QUESTIONS? ...
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