3.8 THE ANALYTICAL DESCRIPTION AND IMPROVEMENTS OF NTCL ACCORDING TO SYSTEM ENGINEERS
Telecom Networks are usually divided into three distinct layers viz. Access layer, Convergence layer and Backbone layer. Access layer carries the last-mile traffic i.e. Voice/Data/Video traffic from customer premises equipment (CPE) to respective local exchange/metro centre, whereas Convergence layer carries the traffic within a city or within a region. The backbone layer is the information highway that carries all inter-regional traffic and interconnects each region with gateway.
Various media used by Nepal Telecom for Backbone
1. Microwave Radio:
Present Backbone Radio Network of Nepal Telecom is as shown below:
2. Optical Fiber
2. Optical Fiber
Salient features of present Optical Fiber Backbone:
* Route Length of East-West OF Network: Approx. 900 Km (Single Mode- 24 Core fibers, 3x40/33mm HDPE ducts laid in parallel).
* Backbone capacity: STM-4 (252 E1).
* SDH Equipments (Siemens): 6xSTM-16, 19xSTM-4 & 54xSTM-1.
* Links 18 districts and 79 Exchanges
* Lamahi - Kohalpur - Lamki - Dhangadhi – Mahendranagar section yet to be completed (approx. 350Km)
* Optical Fiber in Ground Wire (OPGW): 2 fibers leased from Nepal Electricity Authority (NEA) for Hetauda-Patan-Marsyangdi-Pokhara-Kaligandaki-Butwal Link.
* OPGW Route Length: Approx. 342 Km (60+167+115 Km)
* Leasing Rate of OPGW: NRs. 29,260/pair fiber/Km/Year (Approx. US$ 410/pair fiber/Km/year )
3. Satellite Link ( R-SAT):
To carry Regional trunk traffic R-SAT at Biratnagar, Pokhara, Bhairahawa and Nepalgunj are connected with Kathmandu with 120 circuites (4 E1). Incase of failure of Radio or Optical fiber link those R-SAT links are used as backup.
Utilization of Current backbone Network capacity
Ongoing and Future Programs
The above data shows the present bottle neck condition in Backbone. To cater the ever growing
demand of GSM, CDMA, PSTN and other voice &data traffic and at the same time to build IP backbone,Nepal Telecom has planned to take the following actions:
1. Build Regional NG-SDH backbone (TDM & IP backbone with STM64 and DWDM equipments )
2. Build NG-SDH network in Kathmandu valley (TDM& IP network with STM64 & DWDM equipments)
3. Build NG-SDH backbone along the Arniko Highway to connect with China ( TDM & IPbackbone with STM-16 equipments)
4. Upgrade Western-Region Radio backbone network from Bhairahawa to Mahendranagar(Bhairahawa-Dhangadhi STM1- 4+1, 252 E1 and Dhangadhi-Mahendranagar STM-1, 63E1).
5. Upgrade R-SAT network (from 120 circuits to 480circuits) & establish R-SAT at Dhangadhi (in addition to D-SAT terminals)
The planned networks are shown below:
1. Microwave Radio:
Project Status: In process of tendering
Expected project execution date: by end of 2007
Funding: NT's own fund (Bhairahawa to Kathamandu there is a OF ring network, so the traffic will be carried by Radio as will as OF ring as redundancy)
2. NG-SDH Optical Fiber Network (Regional, Sub-Regional and Arniko Highway project):
Project Status:- Regional NG-SDH Backbone: in Tender evaluation phase
Sub-Regional NG-SDH Backbone: in process of tendering
Arniko Highway NG-SDH Backbone: Survey &Design review work completed
Expected project execution date:- by end of 2007
Funding:- Arniko Highway NG-SDH project with grant from Government of China and other by NT's own fund
Salient features of proposed Regional/Sub-Regional
NG-SDH Optical Fiber Backbone:
* Based on Next Generation(NG)/MSTP platform and with DWDM (1st time in NT's network)
* Broadband TDM & IP Backbone with the same SDH equipment.
* All equipments are OMSN Nodes (voice, data and video on single platform, MSTP).
* Core Router/L3 switch at each station( with FE, GE, E1 & STM-1 interface).
* DWDM equipments are used between Hetauda and Patan and other stations are also ready for DWDM connection( by color interface/transponder)
* All Regional Nodes are STM-64 (10G) type & Sub- Regional nodes are STM-16 (2.5 G) type.
* Out of 10G bandwidth 2.5G allocated for Data services and SAN services.
* TDM and IP bandwidth can be adjusted dynamically.
* Application: inter-exchange connectivity, TDM services, carry secured Broadband data/video services like ADSL, VPN, IP-TV, VoD, Triple-play & other IP based services.
* Will open the door for Nepal Telecom's future Next Generation Network (NGN)
Salient features of proposed Arniko Highway Optical
* Link Kathmandu with Khasa, China via Tatopani (approx. 115 Km)
* Sixteen (16) nodes between Kathmandu and Tatopani (5x STM-16 nodes, 4x STM-4 nodes and 7xSTM-1 nodes) with PoS and FE interface.
* Nodes: Sundhara, TTC, Koteswor,Thimi, Bhaktapur, Nalinchowk, Sanga, Banepa, Dhulikhel, Tinpiple, Lamidanda, Dolalghat, Balephi, Lamosanghu, Barhabise, & Tatopani
* Type of OF cable: 36 fiber, single mode (G.652, 1310/1550 nm), Duct type
* Application: Interconnectivity of exchanges in the route, Build information highway between Nepal & China, Create an alternate international gateway route via Hong Kong( no dependency on present
satellite link with limited resource), Enhancement of ICT development in Nepal, Greatly help ISD and internet traffic, can create information highway between India and China etc. India's big operators like Bharati & Reliance have already requested to
get bandwidth in this route.
Project Status: In process of tendering
Expected project execution date: by end of 2007
Funding: NT's own fund
Salient features of proposed NG-SDH network inKathmandu valley:
* 7xSTM-64 NG-SDH nodes (with Router) & up gradation of other nodes
* Multiple ring concept
* Introduction of DWDM concept
3. Satellite Network:
Project Status: In process of contract award
Expected project execution date: by Mid 2007
Funding : NT's own fund
Why Next Generation SDH (NG-SDH)?
Legacy type of SDH equipment doesn't support Ethernet (IP); it only provides TDM interfaces like E1, E3, STM- 1/4/16 etc. So to build broadband data network we need to have separate IP backbone by using Routers, which is very costly solution. But NG-SDH equipment canprovide both TDM and Ethernet interfaces (with L2, QoS, RPR, SAN etc. function). It supports both Packet over SDH (PoS) and Ethernet over SDH (EoS). TDM & Packet bandwidth can be adjusted dynamically. Thus saves CAPEX (Capital Expenditure) and OPEX (Operational Expenditure) and makes the backbone ready for Next Generation Network (NGN).
How NG-SDH Backbone will help to build
Broadband data- network?
Nepal Telecom is going to introduce Broadband services by using ADSL, EV-DO, W-CDMA etc. To
carry all types of data traffic without any congestion and with more security, at all the regional and sub regional nodes, as mentioned above, NT is going to put NG-SDH equipment and Router/L3 switch. The traffic of all the data subscriber via DSLAM, switch at customer premises etc. will be connected to the Router/L3 switch. Every router in this project has 3xGE , 24x FE and 4 canalized E1 interfaces. 2xGE will be connected to SDH equipment and 1x GE will be connected to the DSLAM. FE interfaces will be provided to the data customers like Bank, Corporate houses, ISP etc. If some customer needs less than 100 Mb/s bandwidth, a switch to share all those customers will be used. The 2xGE port of SDH equipment will carry securely all those data from one place to another by using this NG-SDH backbone. The FE interface of 3G BTS will also be connected to the Router via a switch. To connect Media Gateways (MGW) or NG type of switches, SDH equipment itself has additional GE and FE interfaces. At Bhairahwa and Biratnagar in the Router there is a provision for STM-1 POS interface to connect with India for ISP. For the Normal E1 leased lines, it will be connected directly to the SDH equipment. Since NG-SDH equipment has functionality like L2, QoS, SLA, TE, LCAS etc. all the data features like VPLS/VPN, IP-TV, VoIP, Triple /Quad play etc provided be the Access Network can be transparently passed from one place to another by Backbone Network.
Reliability of Backbone Network
After completion of the above projects, all the major cities of Nepal will be interconnected by Optical as well as Radio backbone as a redundancy. As per present network structure only Patan-Pokhara-Butwa-Hetauda- Patan are in Ring structure and the rest are in chain. In case of breakdown of Radio & Optical backbone the RSAT network at all the five regions (with 480 circuits)
will try to provide third redundancy. This will obviously improve our network reliability.
For the optical ring NT is going to implement Resilient Packet Ring (RPR) concept for more efficient
bandwidth utilization of data traffic. India is also having OF network along Nepal's border
area. So, NT is also exploring to build a ring OF network via India. By this way India and Nepal mutually can be benefited in case of fiber-cut on either side of India.
Things to Ponder
* Give more attention to Broadband data service (upgrade present access network to broadband
access network) and utilize the backbone optimally.
* Wherever more bandwidth required introduce DWDM.
* For upcoming Radio network introduce Ethernet interfaces at all station.
* Build Maintenance-Center for Optical as well as Radio network in each region to reduce MTTR.
* Negotiate with NEA for more OPGW links
* Beside utilizing India and China's optical network for Data/Internet communication, the present
Microwave link with Bangladesh can also be upgraded to STM-1 level, by which another international gateway path can be opened.
OPTICAL ACCESS NETWORKS FOR BROADBAND SERVICES
The range and bandwidth of the services which must be offered by access networks have increased significantly over recent years. Furthermore, there is a fair degree of uncertainty about the trend of services which might be demanded by users in the future. Therefore, the architecture of access network becomes an important development area in order to adapt to these trends and make it scalable for future growth. In this paper, an overview of emerging architectures for broadband optical access networks is illustrated.
The access network is the link between end user and the rest of network. It is known as either "the last
Mile " or "the first mile" problem which is the bottleneck of communication system that limits communication speed in any Internet and broadband access schemes.
Broadband technologies, which include all evolving high speed digital technologies that provide consumers integrated access to voice, high speed data, video, video on-demand, and interactive delivery services, are fundamental components of the communication revolution. Over recent years, there are varieties of different and competing access technologies developed. These
include optical transmission techniques such as fiberto- the-home (FTTH) and passive optical network, transmission over the classical links (digital subscribe line, DSL), transmission over coaxial cable modem; the broadband satellites, broadband fixed wireless and wireless local area networks (WLAN) or mobile systems. Those technologies promise to break the existing bandwidth bottleneck and deliver broadband services to both business and individual users. Presently, the leading technologies in the access network are DSL and cable modem which make use of the existing infrastructure. DSL uses the existing copper plant to provide data over voice, independent voice and data transmission, and plain old telephone service (POTS). Cable modem technology is offered by cable companies to provide broadband services to subscribers. Both systems are limited to rates per subscriber in the order of several Mbps downstream and a few hundred kbps upstream due to propagation, congestion and crosstalk considerations. A most promising future proof access technology will be FTTx (fiber-to-the-home, to business, curb, block, etc.) and passive optical network (PON). Fiber optic cables can support an extraordinary highbandwidth - possibly reaching 1000 Mbps, compared to 1.5 Mbps for typical cable and DSL offerings. An FTTx network will remove the bottleneck of other access technologies and upstream bandwidth can be significantly increased. Thus, it will be a long term preferred alternative to other technologies for full services (two-way voice, video, and high-speed data) broadband access network, especially in areas when deploying new access network.
2. BROADBAND ACCESS WITH PASSIVE
Broadband passive optical network is the most promising approach to establish a cost-effective access
network. It achieves excellent economy because multiple end users share optical fiber and central office equipments. Its specifications were originally discussed and determined in Full Service Access Network (FSAN) which an international group is formed by network operators in 1995. Since then, a series of ITU standards G.983 have been developed. The basic architecture of a passive optical network is shown in Fig. 1. An optical line terminator (OLT) usually resides at central office (CO) and provides the interface to access network. From there a single feeder fiber is connected to a passive power splitter. The outputs of passive splitter are connected to subscribers directly or to further splitters via distribution fibers. Since all subscribers share optical power from OLT, this network can be called power splitting PON (PS-PON). Coarse wavelength multiplexing technology (CWDM) is used at OLT and optical network unit (ONU) to separate the downstream and upstream traffic. The downstream uses 1550nm wavelength while the upstream uses 1360nm. With this structure, it can deliver limited digital video as basic band signals, time- multiplexed with voice and data signals.
Usually a broadcast analog video channel may require 3 to 6 Mbps bandwidth depending on the content, while a HDTV channel needs about 20-30 Mbps bandwidth. Since 155 Mbps basic bandwidth is shared among up to 32 ONUs, the number of video channels that can be delivered simultaneously to users as part of basic band signals is limited. This problem will become more severe when PON is extended to residential customers where all 32 users on an OLT may like to view and record different video programs on multiple devices. These limitations will be relaxed partially if the bit rate is increased to 622 Mbps. However, it will require an upgrade of central office equipments and all ONUs. The future access network will use"one for all" architecture, merging the traditional CATV and telephony networks into one. The distribution of CATV signals is an essential part of the service bundle for FTTH. There are two possible technical approaches for delivering this extra downstream signal next to the bidirectional data signals. Frequency division multiplexing (FDM) approach uses a single ONT receiver for both band signals and requires the CATV and data signals to be well separated in the electrical spectrum. The second approach uses a second wavelength to overlay on the existing PON to carry the extra services. By using one infrastructure of PON, the broadcast channels can be distributed simultaneously with basic band traffic, this is called WDM overlay PON.
3. ARCHITECTURES FOR ENHANCEMENT SERVICES
Followed the publication of ITU-T recommendation G983.3, an additional optical spectrum was allocated to increase the network's greater service capability. The wavelength range of 1480-1500nm is dedicated to support one basic downstream channel and 1539-1565nm band is allocated to support a variety of usage scenarios for the enhancement services which can be of distributive nature, like broadcast community access television (CATV), or dedicated connections, such as leased wavelength for particular users. The enhancement band provides the extra services without loss of basic downstream band signals. It can also be used for future network's upgrading to coarse wavelength division multiplexing (CWDM) and dense wavelength division multiplexing (DWDM). This will accelerate the installation of fiber in access network.
3.1. Architecture of WDM video overlays with the existing PON
The huge bandwidth afforded by WDM is critically needed by the access network. With WDM, it is possible to construct wavelength based point-to-point virtual links on a shared PON fiber infrastructure. WDM technology also provides a high degree of configurability, therefore enabling efficient sharing of resources. The high flexibility, capacity and transparency of WDM also makes it an attractive upgrade solution offering additional degrees of freedom due to insertion of various wavelengths to support both entertainment services and more demanding business applications.
The passive optical network can be upgraded with additional services through the overlay of enhancement band within existing architectures. In these systems, the OLT generates both PON signals in basic band and video channels in enhancement band. The two band signals are multiplexed in CO and are sent to the feeder section through a CWDM multiplexer. Fig. 2 shows this architecture where the user can choose either a basic service or an enhancement service. Analog or digital TV signals are first multiplexed using FDM in RF domain. Then the RF signals are used to modulate laser transmitter with the enhancement band. The two band optical signals are multiplexed by a CWDM multiplexer at the CO. Through the feeder fiber, they are transmitted to the outside plant where they are separated to two band signals again. The passive optical splitters further split the two band signals individually. Then according to different end user's requests, enhancement service can be distributed through recombination of the two band signals with a further WDM combiner, as shown in the second
branch in Fig. 2, or, the user can choose basic service with the basic connection By applying this architecture, the users can choose either basic band service or enhancement band service by selecting appropriate connections. With the decreasing price of the receiver at the enhancement ONU, the network will finally provide the enhancement service to all end users. The upgrade architecture of PON can be simplified as shown in Fig.3 where only passive optical splitters are used as branching devices at outside plant. In this architecture, all users can access the enhancement band service.
In the broadcast and select type architecture of PON, more wavelengths can be used and multiplexed at OLT to carry the traffic targeted at different users. The receiver at ONU should be equipped with proper filters to select the specific wavelength. In this way, the end user's extreme bandwidth demands can be met. All architectures ultimately provide end users with improved downstream bandwidth and more services. For upstream traffic, the bandwidth can be enhanced by applying TDM and dynamic bandwidth assignment (DBA) protocol. However, due to passive optical splitters in these architectures, there are some drawbacks which can be categorized as follows:
* For downstream signal, the optical power intended for one ONU is split between all ONUs, leading to a N-fold power budget penalty.
* Since the PON bandwidth is shared between all subscribers, it can allocate bandwidth in a flexible
and dynamic way. However the price for flexibility is that electronic and optoelectronic components in OLT and all ONUs must work on aggregate bit rate.
* Since downstream information is broadcast to all ONUs, these ONUs can receive all payloads of PON and the privacy and security become serious issues.
* Network diagnostics and fault identification of the outside plant in PON are difficult.
3.2. Architectures of wavelength routing WDM-PON
To overcome the limitation of the previous architecture, more complicated WDM-PON architecture can be designed through wavelength routing. In this category, the network is built with wavelength router as branching device. The bundled wavelengths from CO are transmitted through feeder fiber to branching site where the multiple wavelengths can be sorted out to output ports. Fig. 4 shows the basic layout of this architecture where wavelength based point-to-point connections is established using wavelength router. The dedicated optical transmissions in both downstream and upstream direction are bit rate and transmission format transparent. This architecture offers huge bandwidth and high flexibility. It improves the network integrity and privacy significantly.
3.3. Mixed broadcast and wavelength routing WDM-PON
This architecture uses both passive optical splitter and wavelength router as branching devices that can meet end users different requirements and will be the ultimate architecture solution for optical access network shown in Fig. 5. All services which are carried by different wavelengths are multiplexed at the central office (CO) through a WDM multiplexer, and then transmitted through the feeder fiber. At the outside plant, the signals can be processed in different ways either with passive power splitters or wavelength routers. End users can choose basic PON, enhancement PON or WDM-PON network. The architecture has the following features:
* The architecture provides a mixed connection for the basic PON and enhancement PON (WDM overlay).
* Both optical power splitter and WDM wavelength router can be used in the architecture to provide end users either basic PON connection or the dedicated WDM connection.
* The architecture uses power splitters and WDM filters. Therefore, all signals from basic PON and WDM channels can be broadcast to all ONUs.
A number of alternative architectures for upgrading the passive optical network to either WDM overlay PON or WDM-PON architectures were reviewed. The major solutions discussed were application of the enhancement band and implementation of WDM-PON. These architectures use broadcast and select, wavelength routing or the mixture of both topologies. With these new architectures, the end users can share the network resources and network operators will be able to supervise the failure of fiber or terminal equipment in real time. These architectures will also eliminate the need for time multiplexing and ranging protocols as in PON and can provide virtual point-to-point links with data transparency and a high degree of data security and independence. Although WDM-PON architectures are designed for fast growing networks of the future, at present due to some technological issues need to be addressed by component manufacturers, it may be some time before they can be implemented in optical access network. The PS-PON architecture will therefore remain dominant in the market for some time while WDM overlay on PON can be gradually deployed as the transitional stage architecture. With the advances in photonics technologies, WDM-PON will eventually be realized and enable the network operators to provide customers with an extensive range of broadband services. Finally, the access network project that is undergoing for implementation in Kathmandu valley by Nepal Telecom will open the future's door for emerging broadband architecture of access network technology. The deployed fiber networks will be the big asset of Nepal Telecom for coming days and can be considered as diamond mine for the development of information and communication technology of the country. So the management should not hesitate to implement and expand these types of network throughout the country which will provide a strong backbone network for wireline and wireless broadband services.
NEPAL TELECOM AND CDMA
The proposed Plan of Nepal Telecom (NT) aims to expand telecommunications facilities, provide new
services, and strengthen NT in the context of new liberalized competitive regime envisaged by Government of Nepal. This is to Provide additional One million telephone lines (30% fixed and 70% mobile) based on CDMA2000 1x Technology covering urban, suburban as well as maximum possible rural areas. The project aims to provide “on-demand” telephone lines in all cities, towns and commercially active rural centers, Increase the Tele-density of telephone lines, and Serve most rural areas of Nepal that are characterised by low population density, long distances between settlement areas and unfavourable geographical and climatic conditions, mid mountain areas and southern plain areas (Terrain belt) by deployment of CDMA2000 1x Network.
CDMA2000 1x Network Introduction and Deployment
CDMA2000 1x system has more advantages than other mobile system, this technology will help network operator to make best use of their resources such as frequency spectrum and will make the operator have strong competition ability. This is the best technology for mobile telecommunication at this time. And CDMA2000 1X can still be smoothly upgraded to 1XEV-DO, 1X EV-DV. Network plan is solidly based on the reality of telecommunication infrastructure. The design and network solution is based on accurate site data, extensive field survey, exact network planning and RF engineering with full RF coverage of Telecommunication target areas based on the network traffic requirements. The Project is divided into three Networks namely Network I, Network II and Network III. The project is for a total of one million lines on Frame Contract basis. The concept of frame contract is to divide total one million lines in five phases. The first three phases will be of 500,000 lines and the balance lines will be procured in the last two phases. Network I covers CDR, Network II covers three regions WDR, MWDR and FWDR; and Network IIIcovers EDR. Each network has BSC co-located with MSC (in Kathmandu for Network I, in Bhairahawa for Network II and in Biratnagar for Network III). Phase I is a partial Turn-Key Project. All other equipments to be procured under Phase II to Phase V will be installed by NT. This Project covers 75 District Head Quarters and 3914 VDCs.
CDMA2000 1x Network Design
The Project design includes network structure, location of each element, networking configuration, supported subscribers number and traffic (Erl), supported service channels of NT’s CDMA communication system. Wireless communication is inevitable development tendency of the communication industry. As one of Wireless communication technologies, CDMA attracts much attention for its advantages as extensive coverage, full usage of frequency spectrum, excellent service quality, low drop rate, supporting high rate packet data service (upto 153.6Kbps) and so on.
CDMA has the characteristic of high ratio of spectrum usage, thus providing more capacity than other wireless systems during the same frequency scope to meet the capacity request of dense service areas. CDMA provides high voice quality, low drop rate and high rate packet data service, reaching the demand of high-end users and advantageous to compete with other networks. CDMA terminal transmits lower power, being the real “green terminal”.
. System mode: CDMA2000 1X
. Used frequency: 800MHz ; ( 825-835 MHz uplink and 870-880 MHz downlink)
. Grade of Service (GOS):2%, Erl/Subs at Busy Hour for fixed: 0.1, and Erl/Subs at Busy Hour for mobile: 0.03.
. Supported subscribers: 10, 000, 00. These subscribers are distributed in three regions as N-I, N-II and N-III. CDR: 4, 00,000 subscribers, WDR: 3, 00,000 subscribers and EDR: 3, 00,000 subscribers.
. Three sets of MSCs, HLR’s, SMSC’s, BSC’s. One set for each region.
. One set of NMS which manages and monitors the three MSCs. NMS is located in CDR.
. One set of Intelligent Network (IN) is located in CDR. The IN platform will provide services, such as: Prepaid service, Free Phone service; Wireless Advertisement service and Number Portability service.
. One set of ABS system located in CDR have been built in Phase I. Another set of ABS system is in Phase-IV.
. One set of PDSN is in CDR for Phase I, Phase II and Phase III. Another set of PDSN for Phase IV and Phase V.
. Includes 77 BTS in CDR (of which 38 in Kathmandu), 91 BTS in WDR and 39 BTS in EDR for Phase I. Out of 207 BTS in Phase I, 70% of them have been installed and are in operation. The Project is at the end of Phase I stage and is about to commence Phase II & Phase III simultaneously.
. Voice subscriber percentage: 100%, and Data subscriber percentage: 10%
Concept of CDMA
CDMA is wideband technology in which the radio spectrum is divided into carriers which are
approximately 1.23 MHz wide. The traffic channels are created by assigning each user a unique code within the carrier. Each code or user is then ‘layered’ and simultaneously transmitted over the entire carrier. One of the unique aspects of CDMA is that while there are certainly limits to the number of phone calls that can be handed by a carrier, the number is not fixed. Rather, the capacity of the system will depend upon a number of different factors that the operator can control.
CDMA channels are the physical units that are needed to transmit a conversation and operate the system. The number of channels that are needed at each cell site
depends upon a number of different factors including the amount of traffic, data, soft handoffs and overhead channels that the system would need to support. CDMA channels are comprised of ‘logical channels’ which are detailed below.
The traffic channel carries the actual phone call. That is, the voice and control information between the subscriber unit and the base unit.
Pilot channel: The pilot channel is used by the subscriber unit to obtain initial system synchronization
and to distinguish cell sites. Every sector of every cell site has a unique pilot channel.
Sync channel: The sync channel provides the subscriber unit with network information related to cell site identification, pilot transmit power, and cell site PN offset.
Paging channel: The paging channel provides communication from the base station to the subscriber
unit. On this channel the base station can page the subscriber unit, and it can call setup and traffic channel assignment information.
Access channel: The access channel provides communication from the subscriber unit to the base
station when the subscriber unit is not using a traffic channel. The access channel is used for call origination and also for responses to pages, orders, and registration requests. The access channel is paired with a corresponding paging channel. The main effort of this project will be to modernize
the telecommunication network in Nepal. After the successful completion of the project, NT will have an advanced model telecommunication network based on wireless technology, which will be an added impetus to the existing voice as well as data services in the country. The CDMA project being one of the important elements of NT’s Plan, could, therefore, be considered as a viable project not only in financial terms but also from socio-economic point of view. The main effort of this project will be to develop the telecommunication network in Nepal.
SUPPLEMENTARY AND VALUE ADDED SERVICES
provided by CDMA
Call Forwarding allows subscriber to forward call to another preset phone number (PSTN, GSM) or to the subscriber voice mail box.
Inform subscriber of new incoming call when his/ her phone is busy .If received, he/she can switch over the two calls.
Do Not Disturb
If this service is activated the subscriber will reject all incoming calls
This service allows conversation among multiple subscribers both CDMA and non CDMA at the same time.
Mobile Access Hunting
When there is an incoming call, the system rings a number of sets in the preset sequence until the subscriber answers with one. Maximum number of sets in the sequence can be eight.
Remote Feature Control
Allows user to make some service operations on their set from any other available phone sets (CDMA, GSM, and PSTN)
Password Call Acceptance
allows subscriber to selectively accept calls. If this service is activated, the system will require the calling subscriber to provide a password for the call connection.
Selective Call Acceptance
Allows subscribers to selectively accept calls from the list created by the subscriber and reject all other calls.
Subscriber PIN Intercept
When this is activated, a specific call (STD, ISD) or service operation can be made only when the password is input.
Subscriber PIN Accept
When this service is activated, the phone is locked for any outgoing call or other service operation. Only the deactivation operation of this service is possible.
When this service activated and the subscriber is in a two party conversation, one of the subscribers can transfer the call to a third party and disconnect him, so that the other subscriber continues the conversation with the third subscriber.
Voice Mail Service
The voice mailbox can provide storage and retrieval of voice messages as well as auxiliary functions. The voice mailbox number corresponds to the CDMA subscriber number itself. When the CDMA subscriber dials the VMS access number he/she is guided by voice announcement. Any message left in the mailbox can only be drawn by the mailbox owner.
The Fax service is provided in specific fax enabled Fixed Wireless Terminal (FWT). This ser has an interface to connect Fax Machine.
Packet Data Service
PDSN (Packet Data Service Node) service provides high speed internet connection (up to 153.6 Kbps) to users. However this rate is dynamic and can be slower depending on the traffic volume. To use PDSN service, customer needs to register for the service with NT. To use PDSN, the phone is connected to the computer via serial cable.
About End User CDMA Terminals
- Fixed Wireless Phone (FWP) for fixed users. Except Fax service, users can have access to all other basic and value added services.
- Fixed Wireless Terminal (FWT) with Fax Services for fixed users. Including Fax service, user can have access to all other basic and value added services.
- Handheld Terminal (HHT) for Mobile Users Users can have access to basic and value added services.
- PCMCIA card (without RUIM) for Laptop
Users can have access to data services only.
- RUIM card for Mobile Users
It can be used in standard (800MHz) CDMA2000 1x Handsets and PCMCIA card. All basic and value added services are available.
ADVANCED FREEPHONE SERVICE AND ALPHA-NUMERIC DIALING
As people need to make contacts with closed ones and dear ones frequently, they need to keep know telephone number of closed ones. People may have office or business telephone
Number, home telephone number, mobile or cell. They may be in one place in the morning, another in the evening and another place while week-end and holidays. People try to remember telephone number or contact information. However, people can not remember so many telephone no, contact information of all close ones or business firms all time. People try to jot down contact number such as telephone no, mobile, fax, e-mail in clean diary, notebook or any piece of paper or by entering in modern gadgets. Still it’s difficult to find any telephone number as and when required. If telephone number happens to be easy with some sort of pattern in sequence of number, it is easily recalled. e.g. repeated numbers like triple digit number, double digit number, number in sequence, mirrored numbers or so called lucky numbers etc. In many countries, people have to pay additional amount to telephone operator in order get special telephone number. Many of these numbers are called magic number or lucky number believed to boost business. Recently, there was news that a Chinese bidder offered to pay 9 million yuan (US$ 1.1m) for a "lucky"mobile phone number (“135 8585 8585”). People also introduced toll-free number around 40
years back. These are also well known as 800 number. These numbers were subscribed by big and famous business houses and industrial houses. People or customers who dial these numbers need not pay for calling them hence are free to get product related information at no additional cost. Actually, cost of calling these numbers are borne by called party i.e. business houses, support centers etc who subscribe them. People started reserving the toll-free number of their choice so that the public remembers them well, public do not have to write them in special notebook or enter in an electronic gadget to recall as and when required. They started introducing alpha-numeric number. The digit 2 represents ‘ABC’, 3 represents ‘DEF’. Similarly, the available digits from 1 to 9 are represented in the
following pattern :
ABC => 2 DEF => 3 GHI => 4 JKL => 5
MNO => 6 PQRS => 7 TUV => 8 WXYZ => 9 .
The letters are found to be printed in telephone key pad also. The following figure also shows how alphabets can be translated to numbers.
Following these dialing pattern, the most popular dialing number in US and elsewhere are said to be
According to the FCC: of 7.7 million possible 800 numbers, there were over 300,000 "Vanity Numbers" in use by 1996. The original 800 series toll-free numbers
lasted almost 30 years before being exhausted in 1996. The FCC/SMS introduced the 888 series in 1997. 888 ran low in only 2 years. To meet the demand an 877 series was introduced in 1998. 877 started running low in early 1999. This demand has increased because business owners have discovered that vanity toll-free numbers are reliable marketing tool. These numbers which are easy to remember are also known as vanity number.
A vanity phone number brand is simply the best way to keep brand of a company on its customer's mind. As with 800 phone numbers in international arena, 1660 in Nepal’s national business ground can be an instant recall toll-free trigger can increase the company’s leads and sales exponentially, demonstrate the company’s commitment to quality and customer service and upstage its competition- if the right word or phrase is chosen. Many successful companies rely heavily on brand
recognition (large or small). A vanity number that attached to a product or service can greatly increase anycompany’s brand recognition. Your company gains an edge over the competition when customers can identify a vanity number with a brand. In Nepal, Nepal Telecom introduced advanced free phone service for the public. These are popular known as toll-free number. Calling these numbers, caller need not worry about the coast of call. These no are identified by prefix 1660- similar to 800, 877, 888, 866, and 855 numbers in US and elsewhere. How effective it is to put advertisement of alphanumeric telephone number. Like ‘Call 1660-01- TODAY’ or Dial ‘1660-01-PIZZA’ for home delivery or similar ones. These are actually, ‘1660-01-PIZZA’ representing 1660-01-74992 and ‘1660-01-TODAY’ representing ‘1660-01-86329’. These number coveys to public most with less number of words. Just to make sure of concept of alpha-numeric dialing, here are some examples of alpha-numeric dialing as, 1660-01 followed by
637-25 for Nepal
446-25 for himal
46243 for image
52726 for Japan
59684 for jyoti
52684 for kanti
64872 for MITRA
66335 for model
74992 for PIZZA
74466 for RHINO
72844 for SATHI
764-84 for smith
84437 for TIGER
84637 for TIMES
86329 for TODAY
33339 for Fedex etc.
Once these numbers are assigned to one company, other can not have them unless owner release them. So the number represented by popular words like Himal or Nepal once reserved by one group manufacturing one type commodities can not be assigned to other group producing other type of commodities or rendering another type of services. For any caller it is easy to remember and it’s toll free. For the owner of toll-free it’s the virtual number that can be routed to any telephone number depending upon time of call, day of call and place originating the call etc. These advanced free-phone service can be routed to be answered by multiple operators so that if one operator is busy other operator or operators can handle subsequent calls. So there will not be any complain of telephone line being busy or too busy. The calls are not missed. Calls made to advanced free phone number can be answered from office at one location during day and from other remote residential location during morning or evening and on weekends and holidays. Customers can be told to remember one unique number to dial from all over country or selected region whereas they can be answered from nearest branch office to location of calling person. Those who are calling to these advanced free-phone service numbers can also be welcomed in various language announcements to make caller feel homely in their native language or language of their preference. As remittance business is booming in Nepal, all most all big money transfer companies have provided one or more toll-free number across Nepal. Most have these remittance companies have boosted their business many fold and facilitated their customer by providing toll-free numbers even when national economy seems gloomy. Similarly, others from manufacturing, travel business, tele-shopping business, publications house and service rendering companies have provided advanced free phone service in steady. Although, there has been slack in business in past, it is hopeful that business growth will improve in present changed context, making subscription of toll-free numbers necessity. It’s notable that very few NGO (non-government organization) have provided toll-free help-line services. Those who have provided toll-free help-line demonstrate that they are really ready to serve the people and society. Other NGOs especially working against AIDS, family planning, public welfare or insurance companies or those involved in relief works are either unaware of availability of advanced free-phone service can improve their performance or they are somewhat hesitant to serve with toll-free number due to one or another reason.
NG-SDH: AN OPPORTUNE PHENOMENON FOR NEPAL TELECOM
Today’s business environment is more competitive than ever before. With the private operators starting business in the Customer Service sector, Nepal Telecom
is facing a strong competition. Introduction of pioneer service is the key to success and be a market leader. Demand is growing and will continue to grow for new communication services. The competition is also an opportunity to enhance customer service, leading to customer satisfaction and build a competitive edge. With the talk of triple-play services (voice, video and data) and quite recently, quad-play services (data, video, voice and mobile communications traffic), demand of the day is for an infrastructure supporting all these traffic. Quad play services are even more relevant now because of the universal growth in the demand of data and mobile services. All these, also considering the hype of convergence, lead to the requirement of a high-speed resilient network backbone. At the center of new services are Next Generation
Network (NGN) and Next Generation SDH (NG-SDH). With Nepal Telecom poised to deliver new packet oriented services for CDMA (PDSN) as well as for PSTN (ADSL), time has now come to think of an infrastructure supporting packet services optimally. Until recently, the communications world has customarily built new infrastructure or completely new system to take overthe old. But with cut throat competition due to emergence of multitude of service providers, operators can not justify previous levels of Capital Expenditure (CAPEX) on completely new system and equipment while the market demand remains uncertain. Hence, Nepal Telecom also has to find new ways to extract
greater value from its existing infrastructures. The competition demands that not only think about the
CAPEX but Operating Expenditure (OPEX), reliability and quality also have to be kept in check. With this philosophy, NGN and NG-SDH are in the pipeline in Nepal Telecom. NG-SDH regional backbone already has been planned and is in the process of being procured. There has been talk of NGN and it should also be introduced fairly soon. With new operators already starting services, it is high time that Nepal Telecom strategize to venture in the network-carrier services and capacity-provider services sector in addition to customer services. And with multitude of service providers, telecom as well as dataservices, the endeavor would surely turn out to be a winwin
situation for Nepal Telecom.
Next-Generation Network (NGN)
It is the next step in the world of communications, converging three separate networks, viz., the PSTN voice network, the wireless network and the data network (the Internet), into a common packet infrastructure. This intelligent and highly efficient infrastructure delivers a host of new technologies, applications and service opportunities. NGN gives Service Providers more
security, reliability and control while reducing the operating costs. It unites traditional wireline and wireless voice, video and data using a packet-based transport. The advantages of NGN are that it offers more choices– open systems enable multi-vendor participation, innovative
services, compatibility with products and technologies, among others. One key service provided by NGN is the voice portal, which provides callers with anywhere, anytime access to information like news, weather, stock prices, and account balance using a simple voice command and any
telephone. The other various services are next-generation voice-enabled e-Business services, Public Network Computing, unified messaging, media processing services like basic text-to-speech (TTS), and speech recognition, among others.
Next Generation SDH (NG-SDH)
Synchronous Digital Hierarchy (SDH) transmission networks are at most around 10 years old, even less for Nepal Telecom. Hence it is still too young a technology to be replaced. Next Generation SDH technology has been designed to extend the working life of a still vibrant technology in the data age. The Next-Generation SDH, in addition to the traditional SDH functions, also supports various functions including the data-centric applications. It supports native Ethernet services in addition to TDM services previously supported. It should be kept in mind that IP Triple-Play (or Quad-Play) is the best economic delivery of multiple revenue services as is shown by the following:
• IP-Ethernet access solutions cost less to build and to maintain than the existing TDM offering
• Offers a future revenue and service growth based on IP-Ethernet technology
• Migration of TDM voice to New voice model – VoIP- more efficient and effective
• Increasing revenue per customer with new bundled services SDH was designed to handle both voice and data, but was really optimized as a network for voice communications. With increasing demand for data services, for example various services over Ethernet, improvements on SDH were mandatory. Significant technological advances are now enabling SDH to embrace newer types of traffic and customer demand as is shown in the following figure.
The advances have helped in the development of NG-SDH, which accommodates non-voice traffic (such as IP), over Ethernet, in an optimized way. Achievements so far include the integration of packet and TDM traffic
– a single device to support TDM, Ethernet-based packet switching and DWDM interfaces, using SDH in the transport layer. NG-SDH provides a uniform multiservice transport network by converging traditional TDM traffic, private line, video, data, VoIP, and IPTV services, with the classification at the access layer.
NG-SDH in Nepal Telecom
Planning for NG-SDH network in Nepal Telecom has already begun and will be rolled out soon. In the first phase, a regional backbone has been planned and is under the evaluation phase of the tender process.
The regional backbone connects all the regions, and the capacity is STM-64 (10G), 2.5G of which would be used for data traffic over Ethernet. In the network, Patan-Hetauda link uses Dense Wavelength Division Multiplexing (DWDM). The network would provide a backbone for the existing services, such as PSTN, GSM Mobile services and CDMA services, as well as for planned new data services such as ADSL. Fiber is yet to be laid in some parts of the regional backbone network. Fiber is being laid for Lamahi-Kohalpur routes by Optical Network Planning. Another alternative is also being studied, that of using OPGW cable over High Voltage Transmission Line Towers of
Nepal Electricity Authority for the route Lamahi-Mahendra Nagar. This would provide fiber till
Mahendra Nagar for the regional network. In addition, the zonal regions and a ring with four places in Pokhara valley shall be connected to the regional backbones in the second phase. After that, in the third phase, spur network shall be implemented, covering all the regions. The network that would look like after the second phase is complete is given above. A similar network for Kathmandu valley has also been planned. In the valley, there will be 7 main nodes and other smaller nodes of smaller capacity. This network shall provide the infrastructure for various existing services and other new services, including the packet-oriented services. The network covers all of the places of existing exchanges in Kathmandu. The features of the regional backbone network are summarized below.
Salient Features of the Regional NG-SDH Network:
• Inter-exchange connectivity and various broadband services possible
• Multi-Service Access Platform
• Dynamic allocation of bandwidth to TDM and packet services (over Ethernet)
• 7.5G for TDM and 2.5G for packet services
• Protection via path diversity: traffic from one node to another is divided and follow different routes
• All SDH equipments are DWDM-ready for future expansion
• Provision of Quality of Service (QoS), Service Level Agreement (SLA), Traffic Engineering (TE)
• The network also includes core routers at each node (10 nodes in total)
• Supports PDH Interfaces, E1, STM-1, STM-4, STM-16, STM-64, Fast Ethernet (FE), Gigabit Ethernet (GE), Storage Area Networks (SAN) interfaces
• Unlike previously, traffic from outside the valley will be divided and arrive at two nodes, Sundhara in addition to Patan
• In the regional network, Patan-Hetauda link is of more than 10G capacity and uses DWDM between them. Very soon, the much-awaited IP Backbone for the country shall be in place. With the backbone in place, provision of current services and those in the pipeline such as ADSL, PDSN Service for CDMA would be optimized and Nepal Telecom can further think about triple-play services, Virtual Private Networks (VPNs), IPTV, VoD services etc. With various operators in the ICT area, hasn’t time come for Nepal Telecom to start thinking about providing network-carrier services, not only be content with providing customer services? The proposed backbone would certainly be a stepping stone
REVENUE OF NEPAL TELECOM
Nepal Telecom has been established with a mission that is "As a progressive, customer spirited and consumer responsive entity is committed to provide nation wide reliable telecommunication services to serve as an impetus to the social, political and economic development of the country." As mentioned in the mission statement for providing reliable telecom services, Nepal Telecom obviously needs sources of funds which in its case are generated mainly through charging for the services rendered. The tariff and charges for telecom services are approved by the regulatory authority, Nepal Telecommunication Authority. Due to the continuous growth of telecommunication sector in Nepal, traffic and customer's support, Nepal Telecom has been able to generate revenues which are increasing year by year. Nepal Telecom's operating Revenue of last few years have been presented below.
Here we can see how the revenue of Nepal Telecom has risen. Growth rate of financial year 2059/60 with respect to financial year 2058/59 is 17%. Similarly growth rate of financial year 2060/61 with respect to financial year 2059/60 is 15%. From the data presented above and as per growth rate prior to financial year 2058/ 59 it is estimated that annual growth generally in Nepal Telecom's case is around 10 to 15 %. But the contrast has been observed in financial year 2061/62 where growth rate of revenue for the year with respect to financial year 2060/61 was mere 3%. And the main cause was not due to performance of Nepal Telecom but as a result of closure of GSM Prepaid lines for almost more than six months. From the table presented above it is evident that revenue for financial year 2062/63 is crossing Rs. 10 Billion Nepalese rupees which means growth rate of financial year 2062/63 with respect to financial year 2061/62 is almost 20%(Un audited) which is far more convincing.(Note: Others section includes revenue amount of OYT, Installation etc., miscellaneous revenue of Mobile and CDMA, revenue from Leased Circuits, Telex, Telegraph, pay phone, Prepaid calling card etc. are also included.)
From source wise revenue table, it is clear that revenue from local calls is growing year by year. There
are legitimate reasons for the growth like growth in number of telephone lines, addition of value added
services having positive impact on local calls revenue. In recent times, substantial increase in successful calls from PSTN to Mobile and these calls being slightly costlier than the PSTN to PSTN calls have also fuelled up the local revenue. Revenue from STD calls is showing the linear growth but the heartening fact is in spite of continuous reduction in STD prices, STD Revenue is showing growth. This will definitely be a positive sign to narrow the gap between the local and STD call charging. In case of ISD Calls, we can see that due to heavy reduction in ISD calls tariff on Ashadh 2059, revenue from ISD calls in financial year 2059/60 has dropped. But introduction of budget call and other customer oriented schemes, it is gaining momentum in recent years. The source area which always contributed significantly is Inter administration revenue. Growth of traffic terminated in Nepal through NT gateway has contributed well to the treasury of Nepal Telecom. Mobile services is one of the main revenue source of Nepal Telecom and thanks to the faith and support provided by customers towards GSM Prepaid service, Nepal Telecom will climb to new heights in days to come. Since CDMA service has been launched in financial year 2062/63 only, it has already started showing bright signals. We hope that in coming years, CDMA FWT Prepaid, Postpaid and CDMA Limited Mobility services would contribute well to the company's revenue. Now let's turn the focus on current financial year 2063/64 for which revenue has been forecasted as follows:
These revenues are forecasted taking into consideration the existing distributed telephone lines, Average Revenue per user, Line distribution forecast for next year. On this account most importantly for GSM Prepaid 300,000 Lines, FWT CDMA 88,115 Lines and CDMA Limited Mobility 60,000 Lines have been set as the distribution target for next year. If these targets are met along with other PSTN distribution targets we can hope that the budgeted revenue could be achieved or may be even better. Finally in days to come, there would be enough threats and challenges before Nepal Telecom which consequently could have an effect upon Nepal Telecom's Revenue. Private Operators will try to
increase their subscriber base in Fixed, CDMA Limited Mobility and GSM segments. International calls termination to Nepal Telecom's network through UTL gateway and may be other operators venturing into this segment would try to pose threats to Nepal Telecom's Inter administration revenue. Carrier Access Code (CAC) for international calls is another area which needs to be addressed well from Nepal Telecom's point of view. But with the strengths of infrastructure and other resources coupled with the faith and support provided by its customers, Nepal Telecom would certainly live up to the opportunities and hence its vision" To remain a dominant player in telecommunication sector in the country while also extending reliable and cost effective services to all".
LIMITATIONS AND CONCLUSIONS
Nepal Telecom Corporation Limited has undergone a sea change in the development. It has acquired much public faith in the field of communication. It has served the nation with all kind of informational services from PSTN to digital telephony up to now in CDMA prepaid mobile service is being launched in the second phase. It has established East West Optical Highway with the assistance of Indian government as the backbone network.
LIMITATIONS FACED BY NTCL
1. NTCL is not totally free from political and government interferences.
2. There is no perfect correlation between the subscribers demand and the organisation. The subscriber’s number is increasing but the capacity is limited. The subscribers face a great problem in getting the prepaid SIM card. The Black Marketting has been a problem.
3. Radio propagation in uneven landscape is unpredictable. It is very difficult to control the radio signals of the base stations at higher altitude, for example, signals of kakani and nagarkot are appeared everywhere inside the valley. In high altitude land, such as sitapakha, lubu, syoumbhu stup, the signals from many sites interfere with each other.
4. The CDMA service provided by the organisation are often been criticized for electronic malfunctioning and power problems with the set. The voice quality is also far less than expected.
5. The high officials are afraid of being updated with the new costly and quality equipments and technology because of their fear of being on charge of CIAA like Jaya Prakash Prasad Gupta(He was former Minister of Information and Communication)
6. The behavior of the staffs of NTCL is not dedicated to the customer service although the organisation has been transformed to be Company. This is because of the Old Habitual Mindset of the staffs.
SUGGESTIONS AND RECOMMENDATIONS
1. There is no free distribution of shares in market. The no of shares that one organisation of ministry can purchase should be fixed.
2. The number of microcells should be increased in the sector where the quality of signal has degraded for mobile systems. The number of channels should be increased proportionately with the increasing number of the subscribers.
3. The prepaid SIM Card distribution should be more effective. Priority should be given to distributing for different families rather than distributing for more than one member in the same family. The black marketing can be controlled by making compulsion of renewal after every year showing the related documents.
4. Most trusted and reliable company product should be used to purchase the CDMA sets or alternatively better technology should be applied for voice quality. The no of channels should also be made greater. The SKY PHONE should be extended beyond the valley if possible.
5. The true evaluation of a technology and the personnel involved in the better performance of the technology should be rewarded rather than discouraging them.
6. Complete brainstorming of the staffs for providing the organizational service to the customer is most essential.
1. Nepal Telecom Smarica 2063
2. Mr. Prakash Sigdel (Manpower Administration NTCL)
3. Wireless Communications Principles and Practices, Second Eddition
• Theodore s. Rappaport