Transcript Overview of Voice Telephony Industry and Regulatory Issues

IS605/606: Information Systems
Instructor: Dr. Boris Jukic
Voice Telephony:
Technology and
Industry Overview
Telecommunication Industry:
Carriers
LATA

Carriers
–
In the United States
 U.S. is divided into regions called local access
and transport areas (LATAs)
 About 200 LATAs nationwide
Intra-LATA (Local/Toll)
LATA

Carriers
– In the United States post 1996
 Local
exchange carriers (LECs)
provide service within a LATA
 Incumbent LEC (ILEC) is the
traditional monopoly carrier in the
LATA
 Competitive LEC (CLEC) is a
new competitor
LEC
ILEC
CLEC
Inter-LATA (Long Distance)

Carriers
LATA
IXC
LATA
–
In the United States
 Inter-exchange carriers (IXCs) provide service
between LATAs
–
LEC versus IXC distinction is used by data
carriers as well as voice carriers.
POPs
–
In the United States
 Point
of Presence (POP) is a place in a LATA
where all carriers interconnect to provide
integrated service to all customers
LATA
ILEC
CLEC
POP
IXC
IXC
IXCs carry
traffic to POPs
in other LATAs
Regulation of Land-Line Telephony

Regulation
–
Why regulation? Two Main Reasons:


–
–
–
–
An industry that supplies essential services where only one organization can operate
efficiently in a given market is a "natural monopoly.“
Basic telephone service is considered a public utility whose efficient operation is in the
public interest
the monopolistic aspect of the basic telephone service industry is debatable
First steps to regulation were taken by the states in the early 1900s; now all 50
states plus D.C. have commissions that regulate intrastate
telecommunications.
State regulatory agencies are generally known as public utility commissions or
public service commissions.
The Federal Communications Commission (FCC) was created by the
Communications Act of 1934. Independent agency charged with regulating
interstate and international communications originating in the United States
Regulation of Land-Line
Telephony

Common Carriers: carry signals between
customer premises
–
–
–
Domestic Telephone Service provided by a single
telephone carrier within many countries: PTT –
Public Telephone and Telegraph Authority
Rights of Way: government permission to lay wire
along roads, rails and in other public areas
Tariffs are the published rates, regulations, and
descriptions governing the provision of
communication services.
Regulation and Carriers

International Service (Between Pairs of
Countries)
– Provided by international common carriers
(ICCs)
– Allowed carriers, prices, and conditions of
service are settled through bilateral
negotiation between each pair of countries
Country 1
ICC
Country 2
Basic Telephony Infrastructure:
Public Switched Telephone Network (PSTN)
Local PC
C.O.
Belongs to LEC
(Local-Exchange Carrier)
Remote PC
Local loop
Modem
Modem
LATA - B
Local loop
Inter-exchange
circuit
LATA - A
P.O.P.
P.O.P.
Belongs to IXC
(Inter-eXchange Carrier)
GOLDMAN: DATACOMM
FIG. 01-03
C.O.
PSTN: Local Loop
CO
“The Local Loop or Last Mile”
CO
CO
Reg. De-Reg.
CO
UTP, Coax, & Fiber
are run into neighborhoods
to serve businesses and homes
Terminating
Equipment
“NID”
Thousands of Central Offices (COs) that house telecom equipment.
Some serve as “end offices” and some just as tandem offices.
COs are connected using high-speed, redundant circuits (e.g., ATM over OC-48)
PSTN: Digital Trunks and Mostly Analog
Local Loops
Circuit: End-to-End Connection Between Two Subscribers.
Switches: Voice switches are Circuit-Switched.
Local
Loop
(Analog)
Residential
Telephone
(Analog)
Local
Loop
(Digital)
Switch
(Digital)
Switch
(Digital)
Trunk Line
(Digital)
PBX
(Digital)
Switch
(Digital)
Analog-to-Digital Conversion
(ADC)

Sampling of the Voice Signal
–
–
–
–
Each second is divided into 8,000 sampling periods (Nyquist’s Law)
Each sampling period is 1/8,000 of a second
Voice intensity in each sampling period is recorded as fraction of a
maximum value (255).
The decimal value (210 in this example) is converted into an 8-bit
binary value, 11010010
Intensity
Value
210/255
(1010010)
Sample
1/8,000 sec Sampling Period
Transmission Rates

Transmission Rate for a telephone line
– 8,000 samples/second * 8 bits/sample = 64
kbps
– This is why telephone channels are 64 kbps
Mobile (Cellular) Telephony: Analog vs.
Digital

Analog: broadcasts audio as a series of
continuously changing, voltage levels representing
the amplitude of the voice conversation.
–
Each call is sent through a channel separated by 30
kHz: Frequency Division Multiple Access (FDMA)
• Digital: quantizes the voltage levels into a number of bins
(typically 28 or 256 representing 8-bit encoding).
•bins are encoded as a binary number and sent as a series
of ones and zeros.
•Multiple conversations are possible over the same channel
Mobile (Cellular) Telephony: Digital
Advantage

It economizes on bandwidth.
–





More digitized conversations per frequency band
Superior quality of voice transmission over long
distances.
More difficult to decode.
It can use lower average transmitter power.
It enables smaller and less expensive individual
receivers and transmitters.
It offers voice privacy.
Desirable Frequency Band for Wireless
Providers: “Golden Zone”




At lower frequencies, there is little total bandwidth.
At very high frequencies, propagation is poor.
Mobile devices tend to work in the “golden zone”
from the high megahertz to the low gigahertz range.
Frequencies in the golden zone are limited and in
high demand.
– Very expensive to obtain
– EU wide auctions for 3G spectrum yielded > $100
Billion
Generations of Cellular Service
Generation
First
2nd
2.5G
3G
Technology
Analog
Digital
Digital
Digital
Data Transfer
Rate
Data Transfer
Is Difficult
10 kbps*
World
Standardization
(and therefore
roaming)
U.S.
Standardization
20 kbps to 144 kbps
144 kbps to 2 Mbps
Poor
Good
(GSM)
Based
on 2G
(W-CDMA,
CDMA-2000,
and other
systems
may compete)
Good
(AMPS)
Poor (GSM,
CDMA,
TDMA,
& CDPD)
Based
on 2G
?
*Sufficient for Short Message Service (SMS) and wireless Web access
using the Wireless Access Protocol (WAP)
3G Speeds (Throughput Rates)

ITU Speed Requirements for 3G
–
–
–

2 Mbps for fixed devices
384 kbps for walking people
144 kbps for automotive users
Anything Less is 2.5 G
–
Some 2.5G vendors call themselves 3G but are
not
U.S. Cellular Telephony Usage Lag

The U.S. lags many other countries in cellular telephone use.
–
Europe and Asia-Pacific have higher rates of usage

–
The rest of the world also has very high usage rates when adjusted for
per-capita income
U.S. wired telephone charges are low, and in the case of local loop
not based on usage

intensive usage of mobile telephony for local loop purposes is less
attractive
–
The lack of a dominant U.S. standard for 2nd generation cellular
telephony
–
Pricing schemes in U.S. discourages intensive use (receiver-based
charging)

–
Recently, per-unit of usage prices have dropped significantly
3G deployment may change the perception of the “Lag” (stay tuned)