This document discusses the emergence of system-on-chip (SOC) semiconductors to address the need for highly integrated, high-density, and low-power voice-over-packet (VoP) equipment solutions. It describes how SOC-based VoP processors integrate multiple digital signal processors, microprocessors, memory and other resources onto a single chip. This allows for solutions that are more scalable, flexible and energy efficient than traditional discrete component-based VoP modules.

1. Communications Design China • Conference Proceedings 161
Abstract
Semiconductors, specifically digital signal processors (DSPs)
and packet processors, provide the enabling technology to con-
verge voice and multimedia onto packet data networks. To
achieve the requirements of carrier-grade density and
functionalities, Voice-over-Packet (VoP) equipment will require
highly integrated, high-density, and low-power solutions. To
address this need, we are seeing the emergence of new class of
semiconductors utilizing system-on-chip (SOC) methodology
to deliver complete VoP solutions including embedded DSPs,
microprocessors, memory and packet processing, as well as sig-
naling and network protocol software all managed though an
easy-to-use application programmer interface (API).
Convergence of the Voice, Video and Data
Today’s communications traffic is predominantly made up of
data traffic unlike in the past when it was dominated by tele-
phony driven voice. This phenomenon has lead to the emer-
gence of a market for voice-over-packet equipment that can
carry voice reliably and cost effectively over data networks.
According to Synergy Research Group, the market of for Voice-
over-Packet (VoP) equipment in carrier networks will be 5 mil-
lion ports in 2001 and will grow to 170 million ports by 2005.
To “cross the chasm” from niche application to mass deploy-
ment, however, will require a quantum improvement in equip-
ment integration, scalability and cost. Achieving this improve-
ment will require a likewise quantum improvement in the un-
derlying semiconductor technology. Before we discuss VoP
module and design we will first review the architecture of a
typical high density VoP gateway.
High Density VoP Gateway Architecture
Figure 1 below provides a representative design for a high den-
sity VoP gateway where the gateway functions are allocated to
various modules in the gateway and those modules are inter-
connected via a back plane. TDM samples from the PSTN I/O
Controller Modules are relayed over an H.110 TDM bus or the
PCM samples are encapsulated into cells or packets to be sent
over the bus to the Voice over Packet/Universal Port Modules
(VoP/UP). The packetized output of the VoP modules is sent
over the packet or cell bus to the Packet I/O Controller for
Convergence through
scaleable SOC solutions
Chris Martin
Vice President, Marketing
RealChip Communications Inc
transmittal over the packet data network. A switching fabric
provides for the routing of cells or packets through the chassis.
Each module provides the appropriate header information that
is used by the switching fabric.
VoP Module Design
The VoP Module provides the functionality to convert TDM
voice to VoP and other functions as show in Figure 2 below. In
the PSTN to Packet Network direction, the VoP Module re-
ceives the 64KBPS data stream from the PSTN I/O Controller
Modules and outputs packets or cells to the Packet I/O Con-
troller Modules. Similarly, in the packet network to PSTN di-
rection, theVoPmodule receives packets or cells from the Packet
I/O Controller Modules and outputs 64KBPS data streams to
the PSTN I/O Controller Modules.
Figure 1. High-density gateway architecture
Figure 2. VoP Functional Diagram

2. 162 Communications Design China • Conference Proceedings
VoP Module Design -Discrete Component Solution
The traditional VoP Module used by equipment manufactures
consists of discrete components including multiple general-
purpose DSPs in what is commonly referred to as a DSP farm,
along with a microprocessors, memory devices, aggregation
logic, and backplane interface logic as well as the required voice
and data processing, signaling and network protocol software.
Aggregation logic is required to aggregates packet or cell
streams from multiple DSP and also to provide the IP header or
ATM SAR function. A host processor provides configuration
and software download of the DSPs as well as assisting in call
establishment and other network management functions con-
trols the DSPs. Figure 3 below shows the layout of a typical
VoPModule using current discreet component technology. This
module supports approximately 240 channels and dissipates 45
to 60 Watts.
There are four major drawbacks with these discrete compo-
nent solutions:
• They have limited performance capabilities. Today’s VoP
module solutions cannot match the line requirements of
local, metro and wide area networks in that they are only
scalable to 100’s of ports.
• They occupy a large amount of valuable equipment real
estate and dissipate a lot of power. These factors limit the
transmission capacity and thus the port density of the
equipment.
• The use of multiple standalone DSPs integrated together
on a board costs $20 per channel or more.
• They require expensive in-house resources and take a long
time to develop. Many firms see in-houseASIC and FPGA
design capabilities as luxuries they can no longer afford.
Although the processing capability of DSPs has increased
significantly over the last ten years, demand for higher perfor-
mance has increased even faster. The combination of this need
for higher performance, the trend towards increased outsourcing
of the production and development functions, and the standard-
ization of VoP functionality has created a need for SOC-based
VoP solutions.
SOC-based VoP Processor
A SOC-based VoP processor integrates multiple DSPs, micro-
processors, memory and other resources on a single chip. For
example RealChip communications’ MoNET S1000 SOC-based
VoP processor shown in Figure 4 below includes all the func-
tions required for Voice over Packet solution in a single chip.
Functions required for Voice over Packet processing in-
cluded on-chip are:
• DSP farm for voice channel digital signal processing in-
cluding 4 high-speed DSP cores with program and data
memory and individual DMA engine.
• MIPS compatible CPU for supporting VTOA-0113 (ATM
Trunking for Narrowband services), VTOA-78 (Circuit
Emulation Services), VMOA-0145 (Loop Emulation Ser-
vice) and VoIP
• Multiple packet interfaces including 33MHz - 32bit PCI
bus interface, 10/100 Base T Ethernet interface via MII
and Utopia L2
• TDM Interfaces including time slot interchange (TSI)
through a four bit H.100/H.110/MVIP CT bus interface
and an External Synchronous Bus (ESB) for exchange of
voice stream data in multi-SOC configuration
• Multiple test & debug ports including UART serial Inter-
face, JTAG port for DSP Emulation and Debug and
EJTAG port for RISC CPU Emulation and Debug.
• External Memory Interfaces for Flash ROM and SDRAM
interface.
• VoP software suite providing access to all voice and data
processing, signaling and network protocol software
through an open API. Figure 5 provides a diagram of the
software architecture used with a SOC-based VoP pro-
cessor.
The software suite consists of timeslot transports, channel
maps, interworking functions, telephony services and packet
transports. The channel map provides simple coordinate sys-
tem for mapping TDM timeslots to channels, and channels to
Interworking Functions. A channel identification (CID) is the
Figure 3. VoP Module Layout
Figure 4. SOC-based VoP Solution
Figure 5. SOC Software Functional Module

3. Communications Design China • Conference Proceedings 163
standard coordinate for SOC operation and is setup for each
session .
Key Benefits of SOC-based VoP Processor
The benefits of a SOC-based VoP processor over today’s dis-
crete solutions are many fold, including high density, scalability,
and flexibility:
High Density
An SOC-based VoPprocessor such as the MoNETS1000, which
includes RealChip’s Flexi-DMAswitching fabric and DSPload
and memory management software, provides for the highly ef-
ficient utilization of multiple DSP and other resources without
any internal bus limitations. This allows the VoP processor to
scale linearly as additional DSPresources are added from 100’s
of channels per device to 1,000’s of channels. For example our
first generation SOC contains 4 general purpose DSPs and single
RISC processor and supports up to 144 channels. Our second-
generation VoP processor, based on the same architecture in-
creases both the number and density of DSP and processor re-
sources to deliver up to 384 channels. Our third generation VoP
processor with an improvement in DSP density alone will sup-
port over 1,000 channels on a single device by the end of next
year.
Highly Scalable Solution
Today’s discrete component solutions consist of separate voice
and packet processors connected by proprietary interfaces. This
architecture limits VoP module scalability to 100’s of channels.
Typically the interface is limited in bandwidth and the number
of chips that can be supported on the bus. A SOC-based VoP
solution can integrate both the DSPs for voice processing and
general purpose and application specific processors for
packetization along with industry standard interfaces. Combin-
ing voice and packet processing functions on a single chip al-
lows the SOC-based VoP processor solution to scale over stan-
dard IP and ATM interfaces using off-the-shelf board level
switches and can scale to many 1,000s of channels required for
today’s equipment applications.
VoP Module Design - SOC-based VoP Processor
Solution
Figure 6 below shows a multi-SOC OC3 density (2016 chan-
nel) VoPmodule design supporting both VoIPandVoATM. Each
SOC can handle up to 336 channels (G.711, G.726 or G.729
running VoIP or VoATM). The total power dissipation for this
configuration is, 6 SOCs times 3Watts + 6 SDRAM & FLASH
Memory Device times 1.5 Watts (1.5) + 8Watts for the Utopia
and Ethernet switches, 33 Watts. With 2016 channels this yields
less than 15mW per channel.
Conclusion
ASOC-basedVoPProcessor provides original equipment manu-
facturers (OEMs) with many benefits over solutions based on
discrete components:
Improved Performance
SOC-based VoP processors yield the lowest power, highest port
density and lowest cost solution. Current generations of VoP
equipment are limited in performance by the space and power
dissipation requirements of current discrete component solu-
tions. A typical media gateway can only support several hun-
dred channels per VoP module or several thousands of chan-
nels per box. Carrier grade equipment will require tens of thou-
sands of channels with per port costs that are significantly be-
low what is achievable with a solution based on discrete com-
ponents.
Reduced Customer Costs
A SOC-based VoP processor integrates several processors,
memories and interfaces resulting in reduced chip count and
improved equipment reliability. The combination of shorter
development time, lower non-recurring engineering expenses,
lower chip count and improved product reliability provides
customers with a more cost-effective VoP processor solution
compared to an in-house solution.
Improving Customers’ Time to Market
As the competition in the telecom and networking equipment
markets increases, OEMs are looking for ways to accelerate
their time-to-market. Traditionally, OEMs obtained ICs, soft-
ware and algorithms from different vendors and integrated the
components themselves. This process wasted valuable time and
engineering resources. SOC-based VoP processors are deliv-
ered as an integrated set, which enables OEMs to quickly de-
velop and deliver highly, differentiated, cost-competitive com-
munication solutions. By decreasing time to market, customers
can generate additional revenues, avoid certain costs, and gain
increased visibility.
Author’s contact details
Chris Martin
RealChip Communications Inc
1290 Oakmead Parkway, Suite 318
Sunnyvale, CA 94085 USA
Phone: (1-408) 735 9065
Fax: (1-408 735-1806
E-mail: chris.martin@realchip.com
Figure 6. OC3 VoP Module