PowerPoint Presentation

GSM TC Timisoara TC Overview

ContentInput/Output of TC system - global basic functionTC architectureEvolution of architecture with TCIF introduction

1Input/Output of TC system - global basic functionTC G2.5 OverviewInput/Output of TC system TC in BSS (1/4)

BTS - Base Tranceiver StationBSC Base Station ControllerMSC - Mobile Switching CenterMFS - Multi-BSS Fast Packet ServerNMC - Network Management CenterOMC-R - O&M Center PSDN - Packet Switched Data NetworkPSTN - Public Switched Telephone NetworkSGSN - Serving GPRS Support NodeTC - Transcoder

4TC G2.5 OverviewInput/Output of TC system TC in BSS (2/4)The TC G2.5 (A9125) provides:Communication between the BSC and the MSC (encoded traffic)Data-rate adaptationSubmultiplexing on the Ater interface.

A single TC G2.5 can support a number of BSCs. Each BSC rack is connected to a group of up to 6 MT120 boards. This grouping is referred to as a cluster.The TC G2.5 is connected to the other network elements of the PLMN via the following interfaces: The Atermux interface either directly to the BSC or via the MFS The A interface to the MSC In some configurations, the Gb interface between the SGSN and the MFS pass through the TC.

TC G2.5 OverviewInput/Output of TC system External Interfaces (3/4)Atermux InterfaceThe TC G2.5 is connected to the BSC or MFS via the Atermux interface. In the case of a connection to the MFS, the Atermux interface may also convey the Gb interface. If packet channels are present in the Atermux interface, they go transparently through the TC.This is Time Division Multiplexing (TDM), whereby:

The channels either: Are added/dropped in the MT120 (only true for 64 kbit/s channels), or Go transparently through the MT120 (e.g. SS7, OMC-R, X.25 or Gb interface).

The 8 and 16 kbit/s HR, FR, EFR and AMR traffic channels conveyed on the 16 kbit/s bearer channels are processed in the MT120.Submultiplexing 4:1 but only TS0 transparency configurations is supported.

A InterfaceThe TC G2.5 is connected to the MSC via the A interface. This is a TDM interface.

TC G2.5 OverviewInput/Output of TC system External Interfaces (4/4)O&M InterfaceThe BSC performs the O&M access via the Qmux bus, compatible with the G2 TC. This access is used for configuration and supervision of the MT120 board.There is a 1+1 Qmux connection, operating in active/standby mode, per cluster in the TC G2.5 rack. These two Qmux connections are carried on two 16 kbit/s channels conveyed by the first two Atermux links.

TDM interfacesFor the TDM interface, the choice is:

E1 physical linesThe E1 physical interface is located on the MT120 boards.

E1 via STM-1/VC12The SDH interface is located on a plug-onboard. To minimize the number of STM-1 links to be connected, each E1 link can be mapped to any VC12 tributary on any STM-1 link (arbitrary mapping).

Interface to the IP networkGigabit Ethernet 1000 Base-T is used for the IP interface. The TC G2.5 equipped with TCIF board includes a SNMP agent which is managed by the OMC-R.

2TC ArchitectureTC G2.5 OverviewTC Architecture (1/5)The TC G2.5 can have three functional units:

The MT120 board is the main functional unit. It provides the multirate transcoding for up to 120 channels. This board has interfaces for one Atermux trunk towards the BSC and up to four A trunks towards the MSC. There are MT120 WB or MT120 NB, depending on the Adaptive Multi-Rate Wideband (AMR WB) and Adaptive Multi-Rate Narrowband (AMR NB) codec types.

The TCIF board is in charge of terminating the STM-1 link, extracting and forwarding the E1 from STM-1, and ensuring O&M supervision and software management of the MT120 boards. The TCIF boards are in a 1+1 configuration whereby, one carries traffic and the other one is in standby. STM-1 is a 155 Mbit/s interface, included in the SDH family (STM-4, STM-16, STM-64). E1 is transported in VC12 tributary. STM-1 contains 63 VC12. One TC supports a maximum of four STM-1.The TCIF board provides also the IP function for the TC rack (O&M and telecom).

The FANU board provides cooling for the MT120 and TCIF boards in the rack.

TC G2.5 OverviewTC Architecture (2/5)

Basic architecture of TC G2.5 (without TCIF board)

TC G2.5 OverviewTC Architecture (3/5)

Basic architecture of TC G2.5 (with TCIF board)

TC G2.5 OverviewTC Architecture Internal Interfaces (4/5)TC Internal Link (TCIL)The TCIL is a duplicated bus that connects all the MT120 boards of the rack. The TCIL bus is involved in the following functions: Forwarding the configuration information from the BSC to the other MT120 boards Downloading the software from the TC NEM Sending alarm information to the BSC via the MT120 board with a Qmux connection Communicating temperature measurements, power alarms and BSC related information.

High Speed Link (HSI)The MT120 boards are connected to TCIF boards via high-speed links (HSI). Each MT120 board is connected to each TCIF board. The high-speed links carry TDM, TRAU, O&M and signaling traffic.

O&M LinkA link between the TCIF boards carries O&M. This link uses standard ATCA interfaces, i.e. Ethernet, update port.

TC G2.5 OverviewTC Architecture Telecom functions (5/5)Speech Service Functions

The TC G2.5 provides the following speech service functions:

Speech encoding and decoding for:Adaptive MultirateEnhanced Full RateFull RateHalf Rate

PCM A-law or [micro ]-law configurableTandem free operationStatic audio level adjustment in uplink and downlink independently configurable. Range of adjustment is -6dB to +6dB in steps of 1dB.Adjustment of the phase of the blocks in the downlink direction for minimum delayDiscontinuous Transmission. This contains the Voice Activity Detection and the comfort noise measurement in the downlink direction. In the uplink direction, it contains the comfort noise insertion and speech extrapolation.

Data Service Functions

Data-rate adaptation for V.110 formats with intermediate rates of 8 kbit/s or 16 kbit/s.Framing and synchronization of the data blocks.

Evolution of architecture with TCIF introduction3TC G2.5 OverviewEvolution of architecture with TCIF introduction TCIF functions (1/7)The TCIF board provides support for STM1 and IP (TRAUP traffic, SS7) inside the TC rack and also management of the MT120 boards, using the HIS interface.A TC G2.5 rack may be equipped with a pair of TCIF boards, which work in active/standby mode (redundancy).

Main functions:O&M management of the MT120 boards using the HSI interface (configuration, software replacement, supervision)Qmux forwarding ( MT120 boards communication inside a cluster with the master, as TCIL bus is no more used)STM1 supportIP support (TRAUP, SS7 through the SGs slave processors, O&M interface with the BSC and OMC-R). A TCIF board supports Telecom and O&M flow separation.TDM switching (TDM 16K, TDM 64K switches) used for STM1, TRAUP, SS7 trafficMMI Relay (forwarding MMI messages between the MT120 board and the TCNEM fault indication messages)

TC G2.5 OverviewEvolution of architecture with TCIF introduction Data flow BSC IP TC IP (2/7)

TC G2.5 OverviewEvolution of architecture with TCIF introduction HSI interface (3/7)The TCIF board communicates with the MT120 boards using the HSI interface. To make this possible, the MT120 board has to be configured with a proper HSI mode.

The MT120 can be configured in 3 different modes: Mode 1: Stand Alone mode. The traffic terminations of the HSI are not used. TCIL bus is used. Mode 2a: Partial HSI mode. The O&M traffic terminations of the HSI are used. The TCIL bus is no more used. The internal switch in the MT120 is used in pure TDM mode. The time base is then synchronized on the selected HSI clock. Mode 2b: Full HSI mode. HSI is used for O&M, TDM traffic and IP traffic on HSI are used. The central switch of the TCIF is used. Such flexibility is introduced between Ater and A-itf that there is no more a direct and permanent relation between 1 Atermux and 4 A-itf. STM1 links can be used. The time base is then synchronized on the selected HSI clock.

TC G2.5 OverviewEvolution of architecture with TCIF introduction Internal flows examples (4/7)

Internal flows in HSI 2aInternal flows in HSI 2b, full STM1Internal flows in HSI 2b, Ater E1, A STM1Internal flows in HSI 2b, Ater IP, A STM1

TC G2.5 OverviewEvolution of architecture with TCIF introduction TC G2.5 configurations with TCIF (5/7)The following table gives the possible TC G2.5 configurations, with TCIF board:

TC ConfigurationMT120O&MHSISS7Ater/A-itf cross connectTC G2.5 without TCIFMode 1QmuxNoTransparent in MT120MT120TCIF, no IP, no STM1Mode 2aQmuxO&MTransparent in MT120MT120TCIF, no IP, STM1Mode 2bQmuxO&M, Atermux, A-itf, TDM 16K, TDM 64KTransparent in MT120

TCIFTCIF, IP, no STM1Mode 2bTCSL interface with the BSC (over IP)O&M, TRAUPSS7 in TCIFTCIFTCIF, IP, STM1Mode 2bTCSL interface with the BSC (over IP)O&M, A-itf,TDM 64k,TRAUP, TDM 16kSS7 in TCIFTCIF

TC G2.5 OverviewEvolution of architecture with TCIF introduction Application software (6/7)Shell scripts - run during TCIF boot in order to configure the board (load kernel modules, configure the ports in the internal BCM switch, start software applications, configure the IP addresses). Some kernel modules are out of Ramdisk and are loaded by TCIF scripts during boot.

Software applications - there are several main processes running on a TCIF board (both active and standby):oaed O&M interface with the MT120 boards (through hsid process), BSC (through saed process) and OMC (SNMP interface over IP)saed interface with BSC (TCSL interface over IP, for IP BSC), TDM switches configurationhsid interface with the MT120 boardsmmiRelay MMI messages forwarded between the MT120 board and the TCNEM (fault indications).qmux forwarding - Qmux messages forwarded between the MT120 board and the BSC, via TCIF.aps_manager responsible for APS management and STM1 alarms handlingin.tftpd reponsible for FTP between MT120 and TCIF (used for software replacement for the MT120 boards, via TCIF).fibd responsible for FIB table configuration, inside the IP daughter board.

IPMI - used to reset a TCIF board, power on/off of a TCIF board, monitor the power supply, voltage and temperature of a TCIF board, check if a TCIF board is unplugged. TCIF uses a tool, ipmitool, to facilitate the trigger of the IPMI commands.

Software loaded on SGs (Signalling Gateways - two slave processors used for SS7 through TCIF) delivered by Enea/Netbricks

Tools used for debug , read/write register values, monitor E1/STM1 alarms, STM1 laser status, APS status etc. (see next slide)

TCIF processes & MT120-TCIF connectivity

TCIF processes & MT120-TCIF connectivity

MT120 IP allocationidledownloadedactivateddownloadingactivatingacceptingerroraborterrordownloadactivateerroracceptLegendStable stateIntermediate stateManual transitionAutomatic transition (no errors)Automatic transition (after error)abortabortingrejectrejectingrejectTCIF Software management

MT120 Software management

TC G2.5 OverviewEvolution of architecture with TCIF introduction Tools (7/7)There are several applications that can be used on the TCIF board:

tuxTC application used to read/write registers, monitor E1/STM1 alarms, STM1 laser status, APS status etc.Utilitaries for launching ioctl commands to a driver (hsiutil, ipfwutil, )Tool to get the status and to have some debug for the SGs (status)

All the above described tools are located on a TCIF board, under /opt/tcifR-1.1/bin directory.

For useful information you may access also the TC section on our wiki page: http://wiki.mrc.alcatel.ro

www.alcatel-lucent.com

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