1.What is Universal Media Gateway?

The Universal Media Gateway is one of the main equipment in the Access subsystem of
the NGN. In the current implementation of the system in the country this is the main
access system that is being used since it has multiple functions. It is the most economical
solution when the telecom network is part PSTN and part NGN.
Some of the main features of the UMG
It supports interworking between different networks
It provides conversion function between different formats of traffic
Function as a Trunk gateway (TG) and as an Access gateway (AG)
Has an embedded signaling gateway (SG).
UMG8900 can be divided into two parts according to its functionality. This helps to
understand the system better.
Service switching module(SSM):
It processes the formats of various types of traffic flow. It functions as a TG connecting
the PSTN system with the NGN. This is what gives a subscriber in the NGN the chance
to call one in PSTN or any other network even though they work in different ways. In the
absence of a connection with the switch it can act as a switch in NGN. This gives it the
stand alone capability and intern more reliability.
Service switching module (SSM) consists of 4 parts
Main control frame – Management and maintenance functions of the device
and supports service access and process simultaneously.
Service frame – Process services requested by user
Central switching frame – Handles Multi-frame cascading function
Extended control frame - When the device is at maximum capacity. The
extended frame does not support access and process functions of user services,
but provides connection management and control function.


T.A.T Tilakaratne
Department of Electronic and Telecommunication Engineering
9
User access module(UAM):
This is the access point currently provided by Huawie for the users that are in the NGN.
The instrument can be at the UMG itself or function as a RSU from a distant place. It
provides integrated access function for both narrowband and broadband users.
It can even function as an AG if an IP connection is provided.
Card structure of the UMG8900
1. System Management Boards
OMU - Operation Maintenance unit
MPU - Main control unit
CMF - Connection management unit front
NET - Packet switch Net board
CLK - Clock board
CMB - Connection management unit back
PPB - Protocol processing unit
2. Signaling Gateway Board
SPF - Signaling process board
4. IP Interface Process Board
E8T - 8×FE
E1G - 1×GE
HRB – High Speed Routing Board
3. TDM Interface Process
TNU - TDM switch Net Unit
TCLU - TDM Convergence & link unit
E32 - 32×E1
S2L - 2×STM-1 optical
5. Voice Process Board
VPU - Voice Process
Unit
SRU- Signal Resource
unit
Cascading Board
FLU - Front Link Unit
BLU – Back Link Unit

UMG8900 hardware system can be divided into the following subsystems according to
their function.
1. Operation and maintenance subsystem
2. Gateway control subsystem
3. TDM access and switching subsystem
4. Packet processing subsystem
5. Service resource processing subsystem
6. Subscriber access subsystem
7. Signaling forwarding subsystem
8. Clock subsystem
9. Cascading subsystem.

1.7.1 Operation and maintenance subsystem
Control of the UMG is handled by the OMU and MPU it also does maintenance
functions. The instructions to each card originate from here. If the link to the SoftSwitch
fails internal switching is also handled from this section. The terminal access is through
here for maintenance tasks.

1.7.2 Gateway control subsystem
The messages received from the SoftSwitch that concern control of the gateway are
received through this section. The Protocol processing unit handles H.248 and MGCP
standard protocols. In a layered architecture higher level connections have to be
managed. This is achieved from the CMU which is after the PPU.

1.7.3 TDM access and switching subsystem
The access point for PSTN users is through this section. They can connect through the
S2L connection that can connect two STM 1 lines or through the E’1 interface. The voice
coming from the TDM system goes in to a switching network which is controlled by the
OMU or MPU. The signals are split in to signaling and voice.
The access of the RSU equipment that is of the MA5000 is also through the E32 card.

1.7.4 Packet processing subsystem
Picketing of data that goes in to the IP network and vise versa is done in this section. The
types of packets handled are
Voice, video, data

Signaling
Since there are no other UMG in the country only signaling going to the SoftSwitch is
going through this path. Processing of the packets, packet creation, and switching them to
their path is done from the NET Packet switch Net board under the control of the OMU.

1.7.5 Service Resource Processing Subsystem
This subsystem performs media stream format conversion and adaptation adapts
according to the user. The user can be using SS7, R2 or an internal protocol for signaling.
The system has to adapt accordingly and send the replies in the same format.
Format conversion is required since systems work in different ways. They have to be
brought to a common format and also the reverse conversion has to be done.
Main functions handled are
1) Voice transcoding
2) Echo cancellation
3) Announcement play
4) Digit collection
5) Multi-party conference

Voice transcoding is done to reduce the amount of data transfer in the IP side. It also
helps in error handling. VPU is responsible for voice transcoding.
There are many transcoding methods that can be used a chart is given in the Appendix.
SRU is engaged in announcement playing, DTMF generation and detection, digit
collection, audio mixing (conference) and FSK. It handles the Register Signaling part of
R2 signaling. The DTMF generation and digit collection is done in handling R2.

1.7.8 Signaling forwarding subsystem
This subsystem includes some of the components that were included in other subsystems
but also work in signal processing.
According to the present implementation three kinds of signaling enter the UMG from
the E32 interface
R2
SS7
V5.2 (an internal protocol used for signaling with the MA5000)
R2
The Line signaling is directly received from the CMU and sent to the PPU. Register
signaling after being recognized at the TNU is sent to the SRU. The information collected
is sent in a data packet form to the CMU and then to the PPU. Here the signals are
converted in to H.248 and sent to the SoftSwitch. The return path is also the same.
SS7 & V5.2
The signaling is separated at the TNU and forwarded to the SPF. Protocol conversion
from SS7 to Sigtran occurs here. After that the Sigtran messages are sent along the IP
network to the soft switch. The replies come through the same path and commands to the
UMG come through the PPU.

1.7.9 Clock subsystem
Provides the clock signal to the system. For accuracy this can be taken from a satellite.

1.7.10 Cascading subsystem
This connects the central switching frame with the other frames. The connection
management is its main function.
Subscriber Access paths to the UMG
The UMG provides the subscribers with a diversity of service access. The UAM handles
the access of directly connected subscribers. There are two methods of connection.
The unit can be on site and connected by a network cable through the network
It can be at a remote location and connected using a number of E’1 links
depending on the traffic.
T.A.

1.7.11 The UA5000 which is the distant unit does not have a stand alone function.
Figure 7-3: UA5000
PWX- Power
TSS – Test (operates the test relay)
PV8 – Transmission control card
This supports 8 E’1 each with the UMG. The time slots for communication and the V5.2
protocol are handled from this card.
RSP – Bus network control card
A32 – sub card that handle 32 subscribers.
ASL – Coin box connection card has line reversal and meter pulsing capability.
DSL – ISDN connection card
APMA – Broad band service connection card
ADMA – Subscriber interface card for broadband.
An IP network connection is needed to give the broadband service. Then it will be
directly controlled by the SoftSwitch without going through the UMG. The second frame
is an expansion frame which connects with the PV8 using the RSP. From the 31 time
slots in the E’1, one is used to send control messages using the V5.2 protocol. The
identity of the subscriber that is initiating a call, ring signal from the UMG to the
UA5000 and also the commands to the test card are sent through this.