ACKNOWLEDGEMENT

First, we would like to give thanks to Engr. Philander Lomboy for sharing his knowledge in designing a telephone network and for giving us advices to improve this project. For all the values and knowledge he taught us. His ways of being strict made us more determined and challenged us to do our best and finished this design on time. Without his support, this work could not have been completed.We are also grateful to Ms. Lanie, for allowing us to survey in their subdivision and for giving us the latest copy of New Havens Subdivision map. We are also extending our gratitude to Krizzas family for accommodating us in their place. Sincere thanks for each one of us in the group for never giving up and doing our best in making this design possible. Furthermore, we would also like to thank our family for their immeasurable concern, love and support in everything that we do. We also like to thank our friends and all of those who offered help.Finally, we would like to forward all thanks to almighty GOD who gave us strength, wisdom and patience because he makes it possible for us to finish this project.

INTRODUCTION

In order to get a telephone call to travel from one place to another, it must pass through the telephone network. This network is consists of many different parts, operated by many different companies, but are inter-connected using common signaling methods. There are a number of different types of telephone network such as a fixed line network where the telephones must be directly wired into a single telephone exchange known as the public switched telephone network or PSTN, a wireless network where the telephones are mobile and can move around anywhere within the coverage area, a private network where a closed group of telephones are connected primarily to each other and use a gateway to reach the outside world also called as private branch exchange. A phone system comprises multiple telephones used in an interconnected fashion that allows for advanced telephony features such as call handling and transferring, conference calling, call metering and accounting, private and shared voice message boxes, and so on. A telephone system can range from just a few telephones in a home or small business up to a complex private branch exchange (PBX) system used by mid-sized and large businesses.This paper is about designing a telephone network system (outside plant) in one of the village in Novaliches. Our group visited the place twice to

conduct a survey for the number of poles and its IDs, the pole to pole distances or span, pole lines and cable routes, the location of the outside plant access cabinet (OPAC), and classification of establishments. The telephone network design we have done based on the map has 286 lots/households including the vacant lots and 570 lines consisting of distribution points with 22 twenty pairs and 13 ten pairs. With the guidance of our professor and information from the OSP manual, our group had been equipped with knowledge in putting the bonds and grounds as well as installing our own poles and guys. The OPAC is placed in the location that is accessible to operations and close to primary cable route and where it will only need short wires to support the allotted lines. All of what is mentioned here will be thoroughly discussed in the following chapters of this documentation.

DESCRIPTION OF THE SYSTEM

The Bayantel group designs a telephone system for New Haven Village located at Novaliches, Quezon City. The village is consist of houses belongs to the middle and upper class of families and apartments for the middle class of families. They also built a church, offers club house and park for their beloved villagers. Below will be the guide we used in classifying of establishments of village which includes their corresponding penetration factor (pf).

RESIDENTIAL

R1Single Detached, High Cost

R2Single Detached, Medium Cost

R3Single Detached, Low Cost

A1Townhouses, Apartment, High Cost

A2Townhouses, Apartment, Medium Cost

VLVacant Lot

BUSINESS

S3Small Shop

B3Small Size Business Office

MISCELLANEOUS

ClClinic

ChChurch

CHClub House

PPark

BCBasketball Court

The group conducted a survey at New Haven Village to obtain and classify the number of houses from residential, business and miscellaneous. The group also obtained the Pole IDs and locates the Outside Plant Access Cabinet. The penetration factor was given by the instructor Engr. Philander Lomboy after summarizing the numbers of classification of establishments. Outside Plant Access Cabinet were placed in front of the church and side part of the basketball court. The distribution points (DPs) were further calculated and categorized from ten (10) and twenty (20) pairs only in this village.The penetration factors were calculated from the summaries of classification of establishments, and used it as the basis for acquiring the number of pairs needed for distribution points. As summarization from the DPs the group took twenty three (23) of twenty (20) pairs and eleven (11) or ten (10) pairs.

SCOPE AND LIMITATION

The general scope of this project is to design a telephone network from the chosen subdivision. This project is intended for designing a Telephone Network System Outside Plant Access Cabinet in a specific location. Its scope is only from OPAC to distribution point. The classification of establishments, pole location and identification, pole to pole distances, the Outside Plant Access Cabinet location, cable routes, distribution point counts, cable counts, placement of splices, guys, grounds and bonds are the main focus of this project. Designing of own poles, guys and bonds and grounds are considered in the structure.It is only a design of a telephone network system, not constructing the different parts of it such as poles, cables, guys and bonds and grounds. The distribution points can be 10, 20 or 30 pole mounted pairs, but only 10 or 20 pole mounted pairs are used in the system. Proper division of DP boundaries should not exceed to 20 pairs. Considering the cost of materials in designing, placement of guys to poles should have a span of three or more distances with each other that are located in a straight pathway. The bonds and grounds were placed in every intersection, at both end and in every 300 meters of the cable. The proponents are off limits in the construction of the

telephone network design. Maintenance of each pole (electric pole, telco pole or other pole) like destruction is not their obligation anymore.

DESIGN CONSTRAINTS AND STANDARDS

Constraints

Location

The locations geography is the most important consideration. It will define the effectiveness of the system design. It will determine how the operation will work and how effective it will be. Terrains around the location are needed to be considering for it will affect the operating system. It can interrupt the operation and lead to higher cost to avoid the terrains.

ManufacturabilityWhen we say manufacture, it means making a raw material into a finished product. It is hard to create a design especially in large scale industries because large scale industrial operation would be needed. Many types of equipment would be required, mechanical power and machinery would be employed too.

FunctionThe function of the design should also be considered. The functionality of the design depends on the quality ofmaterial used. The material should be a higher quality for this design to function in the best state.

EconomicEconomic constraints are dependent upon the geographic location of poles in a certain subdivision. A subdivision that has more curvature corner has more necessity of materials use as pole. During the survey, it is found that a subdivision that has most curve corners has more needs of poles.

Standards

ICC OSPEngineering Design GuidelinesClassification of Establishments Chapter I, pp. 20-21Pole line design Chapter VI, p. 67OPAC Training and Organization Development Chapter III, p. 30Distribution Points Chapter I, p. 9Survey of Pole Lines and Aerial Cable Routes- Chapter I, p. 20Penetration Factors Chapter I, p. 11DP Sizing Chapter I, p. 13Bonding and Grounding Chapter VIII, pp. 108-111Guying Chapter VII, p. 94

DESIGN CONSIDERATIONS

Telephone Engineering includes tasks such as designing, installing, and maintaining wired and wireless phone networks. The field of Telephone Engineering is moving away from voice operated technologies, as data intense technologies evolve. Telephone Engineering includes working with wired telephone networks, cellular networks, and the satellite systems that support them. The main objectives of the design are to make a proposed design including all data gathered in a certain village. The use of outside plant engineering, which is a branch of telephone engineering, is a tool for construction of plan, upkeeps use and extensions of the plan.When talking about outside plant, we refer to the system composed of the Outside Plant Access Cabinet (OPAC), distribution point, poles, aerial and underground cable, guys, bonds, grounds and other equipment that is situated by using reference of demarcation point in switching facility.

The activities that we performed for the actual design proper as follows:a.) Secure a map of subdivision/village- the group needed to secure a map with a total lots about 250-500. Also, the area involved should only be service by.Outside Plant Access Cabinet (OPAC)

b.) Preliminary survey- lots should be classified by its type (Residential or Commercial).c.) Preliminary Draft- the acquired data should be drawn in cartolina as a draft for the final design materials.d.) Follow-up survey-take into account type, ID and the distance of all the poles within the area covered.e.) Revision of the plan- in this step, the cable routes and distribution points will be drafted.f.) Final survey-actual sample images of the different type of lots should be made available for the final documentation of the design.g.) Preparation of the final draft -obtain an outside of the plant manual.h.) Data gathering- compilation and gathering of the different data acquired throughout the span of the research should be made available for the final draft.

For Pole Setting

A setting pole is a pole, handled by a single individual, made to move watercraft by pushing the craft in the desired direction. Because it is a pushing tool, it is generally used from the stern (back) of the craft. A setting pole is usually made of ash, or a similar resilient wood, and is capped on one or both ends with metal to withstand the repeated pushing against the bottom

and rocks, and to help the end of the pole sink to the bottom more quickly. It can range in length from eight feet (2.5 meters), to over fifteen feet (4.5 meters).For telephone company their actually required to utilize a riser pole beside the OPAC so that if the other pole of other company try to take off their own poles it has its own pole to connect with. In the Philippines almost all poles actually share with the other companies by the agreement/ law that implemented to lessen poles on street.

For Distribution Point

Outside plant (OSP) engineers also often are called field engineers as they often spend much time in the field taking notes about the civil environment, aerial, above ground, and below ground. OSP engineers are responsible for taking plant (copper, fiber, etc.) from a wire center to a distribution point or destination point directly. If a distribution point design is used then a cross-connect box is placed in a strategic location to feed a determined distribution area.The cross-connect box, also known as a serving area interface, is then installed to allow connections to be made more easily from the wire center to the destination point and ties up fewer facilities by not having dedication facilities from the wire center to every destination point. The plant is then

taken directly to its destination point or to another small closure called a terminal where access can also be gained to the plant if necessary. These access points are preferred as they allow faster repair times for customers and save telephone operating companies large amounts of money.The plant facilities can be delivered via underground facilities, either direct buried or through conduit or in some cases laid under water, via aerial facilities such as telephone or power poles, or via microwave radio signals for long distances where either of the other two methods is too costly.

For Aerial cable

An aerial cable or air cable is an insulated cable usually containing all conductors required for an electrical transmission system or a telecommunication line, which is suspended between utility poles or electricity pylons. As aerial cables are completely insulated there is no danger of electric shock when touching them and there is no requirement for mounting them with insulators on pylons and poles. A further advantage is they require fewer rights of way than overhead lines for the same reason. They can be designed as shielded cables for telecommunication purposes. If the cable falls, it may still operate if its insulation is not damaged.As aerial cables are installed on pylons or poles, they may be cheaper to install than underground cables, as no work for digging is required, which

can be very expensive in rocky areas. The aerial cables that carry high-voltage electricity and are supported by large pylons are generally considered an unattractive feature of the countryside. Underground cables can transmit power across densely populated or areas where land is costly or environmentally or esthetically sensitive.

For Underground Cable

Undergrounding refers to the replacement of overhead cables providing electrical power or telecommunications, with underground cables. This is typically performed for aesthetic purposes. Undergrounding can increase the initial costs of electric power transmission and distribution but may decrease operational costs over the lifetime of the cables.

For Guys

A guy-wire or guy-rope, also known as simply a guy, is a tensioned cable designed to add stability to a free-standing structure. They are used commonly on ship masts, radio masts, wind turbines, utility poles, fire service extension ladders used in church raises and tents. One end of the cable is attached to the structure, and the other is anchored to the ground at a distance from the structure's base. The tension in the diagonal guy-wire,

combined with the compressional strength of the structure, allows the structure to withstand lateral loads such as wind or the weight of cantilevered structures. They are often installed radially, at equal angles about the structure, in trios and quads. This allows the tension of each guy-wire to offset the others. For example, antenna masts are often held up by three guy-wires at 120 angles. Structures with lateral loads, such as electrical utility poles, may require only a single guy-wire to offset the lateral pull of the electrical wires.

For Bonds and Grounds

The purpose of grounding and bonding communications systems, as defined in NEC Article 90.1, is to safeguard persons and property from electrical hazards. NEC Articles 250 and 820 describe the specific protection requirements for each type of facility. NEC Articles 800, 810, 820, and 830 permit the use of ground(ing) rods. However, Article 820.100(D) specifies that each ground rod must be bonded to the building grounding electrode system with a No. 6 AWG copper wire using a separate clamp on the rod for attachment of the bonding conductor. NEC Articles 800.100, 820.100 and/or 830.100 depending on the type of communication system.Identifying current flow on the coaxial cable is one process used to verify the ground connections electrical continuity. Where a conventional

CATV service coaxial cable is grounded and bonded to a building grounding electrode system, a part of which is the electrical service ground, a current will flow in the coaxial cable sheath if power is being used in the dwelling and if the power load in the dwelling is not balanced.

DESIGN PARAMETERS

The different parameters that the groups should be taken for consideration were all shown in table 1. It indicates the penetration factor of the classified units. Parks and Basketball court were not included because it does not require any telephone line. The Penetration Factor is the values used to predict the number of lines needed per unit. The lists of tables shown below are the classification unit and the penetration factor.

Classification of UnitsPenetration Factor

R1 (Single Detached, High cost)2.5

R2 (Single Detached, Medium cost)1.75

R3 (Single Detached, Low cost)1.5

A1 (Townhouses, Apartment, high cost)1.25

A2 (Townhouses, Apartment, medium cost)1.0

B3 (Small Business Offices)2.0

Cl (Clinic)1.0

Ch (Church)2.0

CH (Clubhouse)2.0

BC (Basketball court)0

S3 (Small Shops)1

P (Park)0

Table 1: Classification Unit and Penetration Factor

Based on the design, we attain the numbers of units per classification. Therefore, we are able to compute the total number of lines distribute upon

the subdivision. Table 2 shows the computation of number of lines. For conclusion, we computed 570 distributionlines based on the table below.Number of lines = (no. of unit) x (penetration factor)

Classification of UnitsNumber of Units

Penetration FactorNumber of Lines

R152.512.5

R21521.75266

R3571.585.5

A1701.2587.5

A252.512.5

B312.02

Cl11.01

Ch12.02

CH12.02

BC100

S3611

P100

Total Number of Distribution Lines

570

Table 2: Computation of Total Number of Distribution Lines

Table 3 indicates the number of distribution point. Each distribution point (DP) comprise of 10 20 twisted pair cables. We were able to obtain 13 of 10 twisted pair cable and 22 of 20 twisted pair cables.

Type of DP PairDP CountNumber of Cable Pairs

1013130

2022440

Total Number of Pairs570

Table 3: Summary of DP Pairs

Computation of Pole to Pole Distances

During the gathering of data, we are required to attain the distances of each pole to another pole. Therefore we used the pace factor method and then converted into meter. It is the simplest way of obtaining distance between different poles.The pace factor was done by marking a span of meter and one of the member should walk through it. After the marking is done, it is equated the number approximately equal to steps of the span.

Pace Factor

Span = 21.4 mNumber of steps by Krizza = 40 stepsNumber of steps by Jetro = 31 stepsPace Factor = 21.4 m / 40 steps = 0.535= 21.4 m / 31 steps = 0.69

After gathering the pace factor, we obtain the measurement of distance between poles.

DESIGN PROPERMap of New Havens Village

LIST OF MATERIALS

Below are the following symbols used in the design:

Outside Plant Access Cabinet

Own Pole

Other Telecommunications Pole

Electrical Pole

Guys

Bonds and Grounds

Aerial Cables

Distribution Point CountsDistribution Point CapacityNumber of Distribution Points

1013

2022

Total Number of Lines35

Pole CountsType of PolePole Counts

Own Pole6

Tel.com4

Electric Pole48

Total Poles58

Underground Cable DistributionType of CableCable Count

600 x 0.51

Guys12

Grounds and Bonds13

Aerial Cables10 Lines

Cable Lengths

Cable TypeQuantityCable Length

10 x 0.53134m

20 x 0.55212m

30 x 0.53157m

50 x 0.53176m

70 x 0.53188m

100 x 0.58340m

150 x 0.53254m

300 x 0.5158m

600 x 0.5130m

CONCLUSION

The development of the design was on the process. The group has successfully designed a telephone network that able to apply the concepts of all theoretical concepts to actual designing. Consideration in designing a telephone network are great factor in this designing and because of this we were able to differentiate the aerial cables and underground cable and where to place the OPAC in a strategically location to make a low cost of distribution of point and lessen the poles that well build. The groups conclude that the correct selection of an area is a better way to accommodate such design like this to ensure that lines will not be wasted. Having a telephone network design is not easy to make. Consideration in every area of designing should follow. Outside Plant Access Cabinet (OPAC) must be located at a better place so that the cable will be optimized in somehow and outside plant refers to all of the physical cabling and supporting infrastructure (such as conduit, cabinets, tower or poles), and any associated hardware (such as repeaters) located between a demarcation point in a switching facility and a demarcation point in another switching center or customer premises. The group concludes that this design is like a game, need knowledge, efforts, strength and sacrifice to achieve a good design according to what location we picked. Accurate data and proper surveying in the place is needed to ensure that the telephone will work

effectively. Cooperation of every member in the group must be present to create in exact time, because of this we can make easily this design and no wasting of time included.

RECOMMENDATION

The proponents recommend future students who will conduct a telephone network design to consider the selection of the village that will be used. A map with less curves and only straight routes is better for beginners. Also, it is important to choose a village or subdivision that is as much as possible accessible to everyone in the group. This will save time and avoid any hassle in the group in case there is a need to recheck for something in the field for the design. The OPAC should be placed in a location which the cable can be optimized. Take the instructions seriously and carefully follow it to avoid repetition of work. Jot down every data and gathered to make a complete design of telephone network. In creating a better plan or design ask every time the instructor to guide the things you all do for easily attach and bring good output. There should be cooperation from each member of the group and fair task distribution in order to finish the design in time. Time management is very important in doing the plan. Everyone should follow the time and date given to prevent any delay. We also recommend future researchers to design in AUTOCAD ahead of time to prevent rush since this is one of the hardest thing in the project plan.

APPENDICES

RELATED LITERATURE

Call routing in telephone networksby Richard Gibbens and Stephen Turner

Nowadays we take it for granted that someone in England can make a phone call to Australia, or that someone in India can read web pages that are on a computer in Canada. We live in a society in which almost every home has its own telephone line which is connected to a local exchange in the nearest village or town, from there to a main exchange in the nearest city, and from there to any other city in any country in the world. In this way, a person is able to dial a friend in another country just as easily as if they were in the same street.In order that these large and complicated networks can work properly, mathematics and computer simulation have to be used to understand the networks. The aim is to find out how large networks can be designed and controlled to providereliablecommunications systems and to use resourcesefficiently. The reliable and efficient operation of networks is of vital commercial importance to both users and telephone companies, and even modest percentage improvements can correspond to large revenue gains.

A large network is affected by many factors which are often hard to predict. There can be busy and quiet periods through the day. If a television program has a phone-in vote, there can be a sudden overload at one point in the network. If a digger cuts through a major telephone wire while repairing the road, there can be a sudden and unexpected failure. Mathematicians have developed ingenious ways of routing calls which can cope with these unpredictable events. Theserouting schemeswork by searching out the spare capacity in the network so as to route calls away from parts of the network that are broken or full and into parts that are underloaded.A good routing strategy doesn't only need to be able to find the spare capacity in the network. In order to work well in real networks, it needs to besimple, so that thousands of calls a second can be routed instantly. It also needs to bedecentralised; a central controller would be much too slow and could go disastrously wrong if it had a power failure, or got cut off from the rest of the network. Mathematicians have recently been able to show the surprising fact that these different goals can all be achieved simultaneously. Even simple, decentralized schemes can find the spare capacity as efficiently as more complicated schemes.

Erlang's formula

The chances of getting an engaged tone depends on the number of lines out of the village.The Danish mathematician A. K. Erlang was the first to study the problem of telephone networks. In 1917, he looked at a village telephone exchange. He supposed that the village has a certain number of telephone lines going from it to the outside world.We'll call the number of linesC. People in the village want to make calls to the outside world. We don't know when they will want to call or how long their calls will last, but let's suppose that there are on averagevcalls starting per minute, and that the average length of a call is one minute. Erlang wanted to know what fraction of callers would find that all theClines leading out of the village were already full, and so would not be able to make their call until later. He worked out this formula, which gives the answer:

This is calledErlang's formula. The left hand side,E(v,C), represents the proportion of callers that find all the lines already full, and the right hand side gives an equation for that quantity. If you know how bigvandCare, you can work out what proportion of calls cannot get out of the village.

Questions: Without calculating the formula, ifCincreased, would you expectE(v,C)to increase or decrease?Ifvincreased, would you expectE(v,C)to increase or decrease?Answer: If you were to try some different values for the formula, you would find that whenvandCare both doubled,E(v,C)decreases. This shows the surprising fact that using one large link is better than using two links half the size.Erlang's model is a very simple one, but the mathematics underlying today's complex networks is still based on his work.Trunk reservationWhen we try and route calls through a whole network instead of just out of a single village, many surprising things can go wrong. For example, if a call from Aybury to Beeford finds that the direct link between them is full, it is tempting to route it via some other city, say Ceeville, if possible. This is a good thing to do if the network is lightly loaded, but if it is heavily loaded then most calls have to use an indirect route instead of a direct one, thus using two links instead of one. Because each call is using twice as many links as it needs, the network can then only carry half as many calls in total!

Network map showing calls from Aybury to Beeford being routed through Ceeville.

Mathematicians have devised a scheme known astrunk reservationto avoid this problem. We reserve some capacity on each link for directly routed calls. So if a link is becoming full, no indirect calls are accepted on it. The amount of reserved capacity only needs to be very small - maybe space for half a dozen calls on a link that could carry several hundred. This is a very simple scheme, and easy to implement in real networks.The effect of trunk reservation is that we sometimes refuse to carry calls that we could fit in. It seems like this would be a bad thing to do. But in fact, by throwing away a few harmful calls, we can carry far more calls overall.

Sticky routing

Sticky routingis a principle that has been much studied in the last 10 years. Suppose that a call is to be connected between city A and city B but

that all the direct links are currently busy. The routing strategy needs to find a longer path to get from A to B which can carry the call.To do this, city A remembers an intermediate city, C say, to use for suchoverflow callsand attempts to set up the connection from city A to city B via city C. If this connection is accepted then that two-link route is used for this call and is remembered for future calls between cities A and B.

Network map showing change in route from Ceeville to Deeton.

If the two-link connection A-C-B is rejected because it is currently too busy then this call is refused connection (the person calling hears aengaged tone) and the intermediate city is reset at random to another city, D say. The next overflow call between cities A and B will then attempt to use the new path A-D-B.

Modern exchanges route large numbers of calls.

The sticky principle sticks to the same two-link route as long as it is not too congested, and then switches to a new path when congestion is seen. In this way, asticky routing strategy searches for and uses any available spare capacity that exists in the network.

US eyes phase-out of old telephone network

Washington (AFP) - America's plain old telephone network is rapidly being overtaken by new technology, putting US regulators in a quandary over how to manage the final stages of transformation.Though the timing remains unclear, the impact of change and what it means for roughly 100 million Americans who remain reliant on the dated but still-functional system of copper wires and switching stations is up for debate.The Federal Communications Commission is working toward drafting rules in January to formalize the IP transition -- switching communications systems to Internet protocol. And while FCC Chairman Tom Wheeler hails the technological advance, he has also spoken of maintaining the "set of values" that was used to ensure America's universal phone service.But some argue the government should step aside and allow the marketplace to keep moving toward digital standards, given that many consumers already use voice over Internet (VoIP) lines, mobile phones or

various Web-based chat systems such as Skype instead of traditional telephone service.

"Almost everyone will be off this network in the next four years. It is a dead model walking," said Scott Cleland, of the research and consulting firm Precursor LLC, noting that three quarters of the transition is done.Cleland, a former White House telecom policy adviser, said that even if people wanted to keep the old system, "they are not making the switches anymore for this. And the engineers they need to keep it alive are retiring."As a result, Cleland said the question is not if, but when the last people will be phased out of the old system, though the transition should not be harmed by "burdensome economic regulations," such as mandates or price caps.This is a key point for the FCC, which has long been the standard-setter for phone service and requires that it be made available and affordable to all.AT&T, which decades ago had a virtual monopoly on phone services and still operates millions of miles of phone lines, has been pressing the FCC to accelerate the transition."Our current infrastructure has served us well for almost a century but it no longer meets the needs of Americas consumers," AT&T senior executive vice president Jim Cicconi said in a blog post.

Questions on stability, reliabilityFeld said wireless and IP phones are useful, but don't match the reliability of copper landlines for everyday use.Some of these problems became evident after Superstorm Sandy, when local operators declined to fix the old networks and encouraged people to move to new technology."It was not a stable system," Feld said.Officials say the transition is likely to be gradual, without a hard deadline for flipping the switch to digital.

Impact of Internet Traffic on Public Telephone NetworksMr. Balaji Kumar works as a Senior Manager at MCI, where he is responsible for Local Network Strategy and Architecture. His expertise is in telecommunications/data communications in the area of strategy and technology planning, as well as in multimedia communications at both national and international levels. Balajis experience includes methodologies of network planning and process re-engineering, specifically related to the new broadband environment. He is the author of Broadband Communications published by McGraw Hill, and Access Strategies for Communications Service Providers published in New Telecom Quarterly (3Q96).

Soaring Internet usage is bringing the U.S. public telephone system perilously close to gridlock by tying up millions of local phone lines every day beginning in the evening and continuing through the night. Although Internet growth has opened up a whole world of opportunities across the industry, the traffic generated is a serious threat to the local exchange service providers who own the last mile of the access network to the customer(s). This article addresses the impacts and the implications of Internet traffic on the local exchange public network. First, some background on the local exchange telephone network and the assumptions used in the design of telephone networks is provided. Second, the characteristics of voice and Internet traffic are defined. Finally, how Internet traffic impacts the local network is defined. Having identified this impact, some potential solutions for short-term and long- term options will be discussed. In recent years, there has been explosive growth in Internet-related telephone trafficspecifically, calls from residential subscribers across the public switched telephone network (PSTN) to Internet service providers (ISPs). Although there are alternative methods for accessing the Internet emerging, the most publicly- accessible connection currently available is via modem calls across the public telephone network. Internet traffic has significantly increased the load on carrier networks, while providing very little compensating revenue.

While traffic volume poses an immediate threat to the capacity of the public telephone network at a fundamental level, the characteristics of Internet traffic challenge the engineering, forecasting, planning, and operational procedures established by the former Bell system over the past 80 years. Simply put, Internet traffic is the exchange, retrieval, and/or communication of information between computers around the world. For information to be transmitted from one point to another, there must be a transmission medium such as fiber, twisted copper pair, coax, or wireless. Currently, twisted copper pair provides the primary interface between the customers premises equipment and the local telephone company. It gives Internet service providers and users cheap, ubiquitous access with two-way capability plus, its easy to use. The public telephone network converts the digital information produced by computers into an analog signal that is transmittable over twisted copper pair. The quality of the signal is maintained by converting the analog signal back into a digital format at the first interface point of the network: the central office (CO). The information travels between central offices over fiber optic networks in digital format. The terminating central office performs the reverse process converting the digital signal back into analog for transmission from the CO to the customer. The circuit, along with connecting multiple switches, remains intact for the duration of the call. These resources, including switch ports and transmission links used during the call, are not released until the call is completed.

The network architecture consists of a local loop connected directly or via a remote to a central office. This loop from the customer location to the CO is typically 18 kilofeet or less in length. Twisted copper pair dominates the local loop but, in some cases, fiber is being used. In recent years, the segment from the CO to the remote has been upgraded to fiber for economic reasons. Today, there are about 25,000 central offices in the United States. Since connect- ing these COs directly is not a feasible task, network designers introduced a second level of switching called tandem switching or access tandem switching. There are about 1,200 access tandem switches currently in the United States, which aggregate the traffic and route it to the appropriate destination. They typically carry high-volume trunk side (switch to switch) traffic plus a few line side (customer premises to CO) traffic. In other words, very few customers are connected directly to the tandem switches. Long distance carriers usually have their point of presence (POP) co-located with the tandem location. The local service provider hands over to the long distance carrier(s) at the tandem location. Based on data collected over a period of 80 years, the local telephone network was designed for voice traffic. As a result, other signal types carried over the public tele- phone network are forced to emulate voice traffic. This means that any traffic that does not require a real-time connection fax, e-mail, modem and Internet connections, or computers uses the network resources in the same way as voice traffic. Since data traffic does not have the same real-time criteria as voice traffic,

network resources are not utilized as efficiently. In most cases, Internet service providers are connected directly to a high-usage, large central office. However, some Internet traffic traverses through other COs and/or a tandem switch before reaching the terminat- ing CO. In this case, the connection across switches remains intact for the duration of the call.Characteristics of Voice Traffic Based on a detailed understanding of the characteristics of voice traffic, the public telephone network carries voice telephony very efficiently. The assumptions used for voice traffic are as follows: The average residential call holding time is around three minutes. The average business call holding time is around six minutes. The statistical call holding time distribu- tion is well approximated by an exponen- tial distribution. Call arrivals can be represented by a Poisson probability distribution (i.e., a normal bell curve shape). The average residential usage is 3 CCS.1

The average business usage is 6 CCS.

These assumptions are built into todays operations support systems (OSSs) in conjunction with demand forecasting models.These systems monitor trunk usage (capacity) in the network, and utilize the information to

decide when and where additional trunking capacity must be deployed. This, in turn, drives network economics such as return on capital invest- ment and determines how efficiently traffic is carried across shared switching and transmission resources. Appropriate traffic models quantify the efficiencies in terms of grade of service. These models for voice telephony are widely used in standards documents, engineering procedures, OSSs, and cost models for the local exchange network.

Characteristics of Internet Traffic Based on recent data analysis, the qualitative characteristics of Internet traffic are as follows: Internet calls have a mean holding time of about 20 minutes. The average usage is around 27 CCS. The traffic distribution is unpredictable. This means that, with non-negligible probability, one can encounter calls withvery long duration, e.g., 12 hours or longer.

The Internet call duration varies widely from a few seconds to many hours. In contrast, the probability that a traditional voice call will last longer than 10 minutes is very low, and the probability that it will exceed one hour is virtually zero. Internet traffic is also quantitatively different from traditional voice traffic. Public telephone network traffic is typically mea- sured in units of Centum Call Seconds (CCS). Table 1 compares residential voice and

Internet traffic using CCS as a standard unit of measurement. Historically, residential and business subscriber lines generate about three to six CCS, with the residential lines falling at the lower end of this scale and business lines at the higher end. These assumptions dictate the design of the local network. If the same subscriber line carries both voice and Internet traffic, the average load generated per line can increase substantially. The above example illustrates that usage in- creases from 3.6 CCS to 24 CCS with the presence of Internet traffic. When the CCS increase occurs, the network must handle more than its engineered load. On average, todays Internet traffic generates around 27 CCS. For residential voice traffic: An average number of calls per hour per subscriber line 2 calls per hour An average call holding time 3 minutes Average usage on the line 2 (3 60)/100 = 3.6 CCS*For residential Internet traffic: An average number of calls per hour per subscriber line 2 calls per hour An average call holding time 20 minutes Average usage on the line 2 (20 60)/100 = 24 CCS** Where the maximum possible usage per line is 36 CCS.This drives network economics such as return on capital investment and determines how efficiently traffic is carried across shared switching and transmission resources. An Internet user may keep a line open for several days, generating the maximum 36 CCS load for many hours. In summary, the local public telephone network is designed for short calls averaging three

minutes in duration. Since Internet calls occupy a line for an average of 20 minutes, the fundamental assumptions used in the design of the public network become invalid.Impact of Internet Traffic the Internet draws attention to issues that researchers and scientists have been pondering about the network design: Is it capable of carrying broadband information, namely high-bandwidth integrated voice, data, and video? Although the Internet only deals with data traffic, its implications have created chaos for local telephone service providers. One can imagine the problems an integrated broadband network could cause when no planning or design is done beforehand. Internet traffic mostly impacts the local exchange network, however, and not the long distance network. This is because most of the customer traffic originates and terminates with an Internet service provider located within the same local exchange network. The rise in Internet traffic provides an important indication that the center of mass in telecommunications is shifting toward data applications and services. Although the network carries Internet calls in circuit- switched mode, these calls are essentially data calls. The traffic generated in packet data format by PCs can, in principle, be carried far more efficiently and cost-effectively over data networks. Even though suitable data networks exist today, due to cost and equipment limitations, access to these networks is available only to high- volume business users.

Impacts on the Public Network The growth and nature of Internet traffic creates a number of issues for telephone network engineers and planners, the most obvious of which is much higher traffic generated by Internet users. When a significant number of subscriber lines suddenly far exceed the network engineered load, one can expect significant congestion to occur in several parts of the public network. The potential Internet congestion points are:1. The local access switch and its port (line and trunk side). 2. The backbone trunk (transmission links)the link between the central offices, the CO and the tandem switch, or the CO and the ISP. 3. The tandem switch (trunk ports). 4. The local terminating switch connected to the ISP.

Since Internet traffic is typically funneled into the terminating switch in the metro serving area where the ISP is connected, acute congestion is most likely to occur first at the ISPs terminating switch. Line capacity between the terminating switch and the Internet provider can generate as much as 30 CCSor more. Under these conditions, only a fraction of calls are completed; the rest are blocked as a result of line unavailability. To accurately estimate the additional cost to carriers for supporting Internet traffic over the public telephone network, it is natural to turn to traditional traffic models.

However, the characteristics of Internet traffic imply that the traditional models are no longer valid. For example, it is not sufficient to just plug the new elevated subscriber line loads into traditional traffic models and recalculate line concentration ratios because the traditional models tend to underestimate the Internet impact. Hence, new models are required to handle much greater variability such as Internet call holding times and other parameters. Going beyond the fundamental traffic models and capital costs, the increased variability of Internet traffic will impact the operation of carrier networks in a variety of ways including: Operations of network. Facility management. Procedures for load balancing. Monitoring switch capacity and usage. Transmission network performance.

Network service providers have already encountered serious difficulties in areas where Internet traffic levels are significantly high, such as in California. It is important to step back from traditional thinking and evaluate the issues from a long-term perspective. The implications of high Internet traffic, however, extend beyond the internal planning and operation of the network. Increased traffic directly affects the percent- age of completed callsregular voice and 911. Blocking probability for traditional voice traffic

network is 0.05%. With the addition of Internet traffic this number has grown to 4%. Though the actual numbers are small, the percentage of change is very significant. The most impacted local network is in California, where 40% of the Internet traffic originates. This Internet traffic has impacted the core of the local service provider. In this era of increased local network competition, the rise of Internet traffic has opened the door for competitors to gain market share. Because they dont have to work with an existing infrastructure, they are in a better position toGoing beyond the fundamental traffic models and capital costs, the increased variability of Internet traffic will impact the operation of carrier networks in a variety of ways New Telecom Quarterly plan their networks efficiently for the Internet and other new multimedia services.Potential Solutions Slowing the growth of the Internet via tariffs is not a solution. At present, the most common Internet access arrangement is for ISPs to connect to the local terminating switch via large multi-line hunt groups, consisting of hundreds or even thousands of lines. Multi-line hunt groups are typical business lines where calls coming into the customer site are routed to the available line. Typically, a PBX (private branch exchange) or modem banks are connected. Networks take no special actions to identify and route Internet access traffic separately. Voice and data alike use the same switches, trunk groups, and other network resources. Internet solutions can be categorized

into short term and long term. The shortterm solution is usually switch-based. Here, the traffic is routed to reduce the blocking at various locations in the network. The long- term solution blocks all traffic at the first interface point to the public network, then routes the traffic to the appropriate switching platform, network, or carrier. Short-Term SolutionsTrunking Solutions AIN Routing/Numbering Solution Switch-based ISDN Long-Term Solutions Long-Term Solutions Pre-Switch Adjunct xDSL Cable Modem Competition in the Local Network Short-Term SolutionsTrunking Solutions address the problem of congestion in the trunking network and terminating switch. They are technically feasible but may not be within the full control of local exchange service providers. An ISP buys only as many lines as it deems necessary to the terminating switch. Internet traffic is growing so fast that customer retention is not an issue (at least not in the near term), and customer expectations are different for Internet calls. Consequently, with too few lines to accommodate the offered load, congestion is likely to be a chronic problem on ISP lines. Trunking solutions generally attempt to reduce stress on the

public telephone network by de-loading the switches as far as possible, and by trunking Internet traffic more intelligently. Trunking solutions, however, do not address the central problem of Internet traffic, which is routing the Internet traffic over a data network.

AIN Routing/Numbering Solution, the telephone service provider assigns a dialed number (DN) to a pre-advertised Internet or on-line service providers telephone number. Based on the defined trigger from the routing table, the originating switch recognizes that the call is for an ISP. The switch then either routes this call to a tandem or a large switching system that has sufficient capacity to carry the data calls (e.g., an underutilized inner- city switch) or routes the call out of the public network onto a packet network.A potential advantage of the AIN/ numbering solution is that it concentrates Internet traffic in relatively few places (e.g., designated trunk groups) and thereby achieves economic efficiencies in the engineering of CO equipment, as well as minimizing capital expenditure for high- performance interfaces between selected tandems and ISPs. On the other hand, it is difficult to update the tables that identify the calls as Internet or as an on-line service provider. Also, this solution becomes invalid in the future if the same call carries voice and video along with data.

Switch-Based ISDN Data transmission uses only a fraction of the 64 Kb/s circuit-switched bandwidth which is held for the duration of Internet calls. Specifically, this means that data packets are transmitted back and forth across the circuit in rapid bursts followed by relatively long idle periods. Thus, the long-term solution blocks all traffic at the first interface point to the public network, then routes the traffic to the appropriate switching platform, network, or carrier. Bandwidth remains unused for most of the call time. However, ISDN calls do not reserve any fixed amount of bandwidth; bandwidth is used only as required. The packet features of ISDN constitute a different paradigm for communications. Their purpose is to carry packet data traffic, yet they are still not fully deployed. Al- though there are issues concerning the capacity, engineering, and cost of peripherals, ISDN, in principle, constitutes the most attractive solution for identifying and segregating data calls on the access side of the switch. However, the capacity-related issue does not disappear. But in recent years, router-based ISDN seems to be more attractive. Router-based ISDN is different from traditional ISDN implementation because it is not part of the traditional switch. Typically, to provide ISDN, one needs to deploy millions of dollars worth of switches. In the case of router-based IDSN, the interface is like any other line card which plugs into traditional routes, and the cost is in the thousands of dollars. Thus, the router-based solution is a cost-effective alternative, especially when the revenues generated from Internet traffic are considered.

Long-Term Solutions Pre-Switch Adjunct Pre-switch adjunct is similar to the router-based ISDN alternative. The idea of a pre-switch adjunct is to put some equipment in the switching location (wirecenter) between the subscriber and the local access switch. This adjunct equipment could be a modem or ISDN that would perform table lookup on each calls origination to deter- mine whether it is a data or voice call. If the call is a data call, the adjunct equipment would route the call to a data network via the modem or ISDN function, thus totally bypassing the carrier switch. Call setup and billing would proceed normally, and voice calls would be handled as normal. The disadvantage of this arrangement is establishing network management for additional equipment and the additional costs associated with managing the equipment.

xDSL is an emerging technology that would supplement the existing POTS or ISDN line between the subscriber and the local access switch. It provides more band- width from the switch to the subscriber than from the subscriber to the switch. This arrangement is based on the expectation that subscribers will typically want to receive more information (e.g., video images) than they send. xDSL also provides the capability to siphon off data calls on the access side of the switch before they enter the public telephone network to a packet network for efficient transport.

Cable Modems Cable modems utilize a hybrid fiber/ coax (HFC) medium and a media access control (MAC) scheme to share bandwidth among a subset of customers from a cable head end. The technology has the potential to provide high-speed data access to cable- equipped subscribers. Compared with ISDN and xDSL, cable modems represent a solution in which Internet traffic would bypass public telephone networks onto data networks via the CATV network. Figure 5 illustrates this scenario. The implementation details of carrying data over CATV are still being explored. Since cable modem technology is implemented in a shared bus architecture that allows for collisions and retransmissions, the effectiveness of the architecture depends on the media access control scheme, traffic characteristics, deployment topologies, and quality of the transmission network among others. These characteristics of the CATV will affect real-world throughput in realistic deployment scenarios. Even though this solution has potential long-term viability, one cannot be sure until all the technical and business hurdles are cleared.

Local Network Competition Internet traffic has been a boon for competitors hoping to provide local inter- connection services. While local service

With the Telecom Act of 1996, the opening of the local exchange networks, and unencumbered by existing infrastructure, competitors can leap-frog short- term solutions and move directly to long-term solutions.Providers are struggling to decide whether to adopt short-term or long-term solutions and analyzing the cost/benefit tradeoff, competitors have an advantage. With the Telecom Act of 1996, the opening of the local exchange networks, and unencumbered by existing infrastructure, competitors can leap-frog short-term solutions and move directly to long-term solutions. With its focus on creating a competitive environment, the Telecom Act has forced service providers to concentrate their efforts on the service aspect, not on the facilities. For competitors, the act mandates the LECs to provide unbundled network facilities at cost, plus marginal profit to its competitors. As a result, competitors have the opportunity to adopt some of the long-term solutions quickly and easily.Conclusions Internet traffic is essentially data traffic that is carried most effectively over data networks. While short-term solutions for supporting Internet traffic could utilize a number of approaches, long-term solutions based on packet technology are the best solution. The solution, however, depends on the business objectives set by the service providers and their service offerings in the long run. Regardless of the solution selected by a carrier, there is a substantial amount of work required to:

Cost out migration paths. Perform interoperability testing of various supplier equipment. Formulate appropriate engineering and operations plans for the network. Translate these technical advances into attractive products and marketing strate- gies.

At present, a number of incumbent carriers are analyzing the Internet phenomenon and debating the best path to take. Meanwhile, new entrants are moving forward with long-term solutions not only for addressing the Internet traffic, but also for future multimedia traffic. Since the public telephone network currently represents the only near-universal access medium, any long-term solution necessarily involves a staged migration from the present mode of operation toward some packet network solution. The Telecom Act of 1996 opened up the local network, enabling competition to divert some of the Internet and local voice traffic. In fact, competitors can do a more efficient job of not only addressing growing Internet traffic needs, but also other new service(s) on the horizon. They do not have the burden of existing legacy network architecture and support systems.Source: http://ieeexplore.ieee.org/xpl/abstractAuthors.jsp?tp=&arnumber=26022&queryText%3DTELEPHONE+NETWORKING

SPECIFICATIONS

I. Copper CablesConductors are of different types. Each conductor shall be solid round wire of commercially pure annealed copper. The sizes of wire and their nominal diameters are shown in the following table:

AWGDiameterTurns of wireAreaCopper resistance

190.03590.91227.911.01.290.65326.428.051

200.03200.81231.312.31.020.51833.3110.15

210.02850.72335.113.80.8100.41042.0012.80

220.02530.64439.515.50.6420.32652.9616.14

230.02260.57344.317.40.5090.25866.7920.36

240.02010.51149.719.60.4040.20584.2225.67

250.01790.45555.922.00.3200.162106.232.37

260.01590.40562.724.70.2540.129133.940.81

270.01420.36170.427.70.2020.102168.951.47

280.01260.32179.131.10.1600.0810212.964.90

290.01130.28688.835.00.1270.0642268.581.84

300.01000.25599.739.30.1010.0509338.6103.2

310.008930.22711244.10.07970.0404426.9130.1

320.007950.20212649.50.06320.0320538.3164.1

330.007080.18014155.60.05010.0254678.8206.9

340.006300.16015962.40.03980.0201856.0260.9

350.005610.14317870.10.03150.01601079329.0

360.005000.12720078.70.02500.01271361414.8

Telephone Network DesignPage 58