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SVKM’s Narsee Monjee Mukesh Patel School Of Technology Management and Engineering, NMIMS A Report On RF Network Planning For GSM and CDMA By Kashish Parikh UNDER THE GUIDANCE OF Prof Ravindra Bhatt(Lecturer), Parminder Singh Sodhi(Dept Gen Manager) and Vivek Porwal(Junior Manager) Reliance Communications (8th May 2010) SVKM’s Narsee Monjee Mukesh Patel School of Technology Management and Engineering, NMIMS Certificate
This is to certify that Kashish Parikh has submitted his report on RF Network planning under the guidance of Mr Parminder Sodhi (Reliance Comm), Vivek Porwal (Reliance Comm) and Prof Ravindra Bhatt (MPSTME) in Partial fulfilment of IXth Trimester Technical Internship for MBA(Tech) program of Mukesh Patel School of Technology Management & Engineering , Narsee Monjee Institute of Management Studies(NMIMS), Mumbai. ___________________ Mr Parminder Singh Sodhi Prof Ravindra Bhatt (Deputy Gen Manager) (RELIANCE COMMUNICATIONS) ____________________ _____________________ Mr Vinod Bhatia Head of Department (ALL INDIA HOD- RF PLANNING) (RELIANCE COMMUNICATIONS) Acknowledgements I would like to take this opportunity to express my gratitude to all those people who have helped me in the successful completion of my project. First and foremost, I would like to thank my internal guide Prof. Ravindra Bhatt for his immense and whole hearted support without which this project would not have been possible.
First of all, Mr Vivek Porwal who, through his expertise in the field, devised a module that would enable me to understand the concepts of telephony and gradually gather a vivid understanding of my project. His wisdom and support was a great asset and his project planning helped me gain a good insight on the working of GSM & CDMA. My mentor, Mr. Parminder Singh Sodhi, who has lent his support on every occassion and shared his vast expanse of knowledge and experience which were important in understanding the nitty-gritties of the organisation. Most importantly his critical explanation of all my doubts worked in cementing my basics.
Lastly I would like to thank Mr. Sumeet, Mr. Jigar Parikh, Mr. Chirag Shah, Mr. Nishant Jadav and Mr. Sakir Patanwala for creating a amiable learning environment where free flow of knowledge could take place enabling me to get a holistic view of things. -Kashish Parikh * INDEX 1. About the company……………………………………………………………………………6 2. History…………………………………………………………………………………………. 7 3. Introduction To Wireless System…………………………………………………………….. 8 4. Multiple Access Techniques…………………………………………………………………. 15 4. 1 FDMA……………………………………………………………………………………… 16 4. 2 TDMA……………………………………………………………………………………… 17 4. CDMA……………………………………………………………………………………… 18 5. GSM & CDMA Traffic Channels ……………………………………………………………19 5. 1 GSM Channels…………………………………………………………………………….. 19 5. 2 Reverse Link……………………………………………………………………………….. 23 6. Cell Concept……………………………………………………………………………………28 7. BTS & Antenna………………………………………………………………………………… 30 7. 1 BTS……………………………………………………………………………………………. 30 7. 2Antenna Selection Criteria………………………………………………………………………………… 31 7. 3 Antenna Used………………………………………………………………………………. 34 8. Propagation Model…………………………………………………………………………….. 37 9. Softwares Used…………………………………………………………………………………38 . 1 Google Earth………………………………………………………………………………. 38 9. 2 Agilent Wizard…………………………………………………………………………….. 38 9. 3 Mapinfo…………………………………………………………………………………….. 39 10. Network Planning…………………………………………………………………………….. 41 10. 1 Calculation Of Number Of BTS……………………………………………………………41 10. 2 Positioning BTS…………………………………………………………………………… 50 10. 3 Excel Sheet…………………………………………………………………………………53 10. 4 BTS…………………………………………………………………………………………69 11. Optimization Using Agilent Wizard…………………………………………………………70 12. Future Planning………………………………………………………………………………. 73 12. 1 3G……………………………………………………………………………………………….. 73 12. GPRS…………………………………………………………………………………………… 73 12. 3 EDGE………………………………………………………………………………………….. 74 14. References……………………………………………………………………………………… 75 About The Company The Late Dhirubhai Ambani dreamt of a digital India — an India where the common man would have access to affordable means of information and communication. Dhirubhai, who single-handedly built India’s largest private sector company virtually from scratch, had stated as early as 1999: “Make the tools of information and communication available to people at an affordable cost. They will overcome the handicaps of illiteracy and lack of mobility. It was with this belief in mind that Reliance Communications (formerly Reliance Infocomm) started laying 60,000 route kilometers of a pan-India fiber optic backbone. This backbone was commissioned on 28 December 2002, the auspicious occasion of Dhirubhai’s 70th birthday, though sadly after his unexpected demise on 6 July 2002. Reliance Communications, formerly known as Reliance Infocomm, along with Reliance Telecom and Flag Telecom, is part of Reliance Communications Ventures (RCoVL). Reliance Communications Limited founded by the late Shri Dhirubhai H Ambani (1932-2002) is the flagship company of the Reliance Anil Dhirubhai Ambani Group.
Reliance Communications is India’s truly integrated telecommunications service provider. Reliance Communications has a reliable, high-capacity, integrated (both wireless and wire line) and convergent (voice, data and video) digital network. It is capable of delivering a range of services spanning the entire infocomm (information and communication) value chain, including infrastructure and services — for enterprises as well as individuals, applications, and consulting. The Company has a customer base of 105 million including over 2. 5 million individual overseas retail customers.
It ranks among the Top 5 Telecom companies in the world by number of customers in a single country. Reliance Communications corporate clientele includes 2,100 Indian and multinational corporations, and over 800 global, regional and domestic carriers. A pan-India, next generation, integrated (wireless and wireline), convergent (voice, data and video) digital network that is capable of supporting best-of-class services spanning the entire communications value chain, covering over 24,000 towns and 600,000 villages has been established by Reliance Communications.
On 30th December 2008, Reliance Communications became the first telecom operator in the history of Indian telecommunications to simultaneously launch its GSM services in 15 circles, namely Andhra Pradesh, Chennai, Delhi, Gujarat, Haryana, Jammu & Kashmir, Karnataka, Kerala, Maharashtra, Mumbai, Punjab, Rajasthan, Tamil Nadu, Uttar Pradesh(East & West) thereby establishing itself as a pan-India operator. It already operates GSM services in 8 circles namely Assam, Bihar, Himachal Pradesh, Kolkata, Madhya Pradesh, North Eastern states, Orissa, West Bengal.
Today, Reliance Communications is revolutionizing the way India communicates and networks, truly bringing about a new way of life. History Building wireless network was not an easy task. It has undergone series of changes and modifications over a period of time. The following table gives a brief summary about the sequence of events that took place in the history of communication technology. Year| Event| 1870| Alexander Graham Bell’s invention of telephone. | 1880| Heinrich Rudolph Hertz discovered energy transmission through the air. 1892| Nikola Tesla created basic design of radio. | 1897| Guglielmo Marconi demonstrated wireless communications. | 1905| First transmission of the speech and music through the air. | 1928| Police car radio dispatch in Detroit. | 1933| Two-way (push-to-talk) mobile application using amplitude modulation (AM) at the police department in Bayonne, New Jersey. | 1935| Frequency modulation (FM) technology introduced. | 1940| Mobile application using FM at the Connecticut State Police, Hartford. | 1946| Mobile radio connection with Public Switched Telephone Network at St.
Luis (just 3 channels supported). | 1946| First public mobile telephone service introduced in 25 major USA cities. | 1947| Cellular concept originated at Bell Laboratories. | mid 1950’s| First full duplex (simultaneous two-way) mobile transmission for the Philadelphia police. | 1964| Improved Mobile Telephone Service (IMTS) introduced in the USA (total of 33 channels covering 50 mi. in diameter). | 1974| USA Federal Communication Commission (FCC) allocated initial 40MHz of the spectrum in 800 MHZ band for cellular systems. 1976| First commercial communication satellite system launched. | 1981| FCC release of 40 MHz bandwidth 800 MHz band for commercial operation of cellular systems. | Early 1980’s| Analog cellular systems introduced in USA (AMPS), Europe (NMT, TACS, C-Netz, Radiocom2000…) and Japan (NAMTS, JTAC, NTT). | 1986| Additional 10 MHz of spectrum for the cellular systems in the USA released to the existing carriers. | Late 1980’s and 1990’s| Digital cellular systems introduced in USA (TDMA, CDMA, iDEN-SMR, GSM PSC 1900), Europe (GSM, DCS 1800), Japan (PDC). 1993| USA Federal Communication Commission (FCC) allocated 120MHz of the spectrum in 1900 MHZ band for cellular PSC systems – auction (in 1994 to 1996) money reached 20 billion $. | 1997| Iridium (66 LEO satellites) system launched – project failed 2000! | 1997| Wideband CDMA (WCDMA) considered as one of the 3G technologies for UMTS (Universal Mobile Telecomm. Systems). | 2001| GPRS system operational in Europe. | 2002| UMTS WCDMA operational. | INTODUCTION TO WIRELESS COMMUNICATION Wireless communication can be simply defined as the process of transmitting and receiving data, (text audio video etc. using free space as a transmission medium. Wireless communication system generally has transmitting antennas and receiving antennas. In this, information is modulated with high frequency and then this modulated frequency is transmitted by using transmitting antenna. On the receiver’s side, there is an antenna present which captures only pre-assigned frequency and rejects all other frequencies. The received signal is then demodulated to get the data in original form. Block Diagram of General Wireless Network Wireless network consists of following components: * Switching systems
Switching systems provide the function of transferring transmissions from one circuit to another in the network. The switching function controls the routing of signaling and user information to specific nodes in the mobile network. The switching systems consist of the transmission facilities and computing platforms that control the switch circuits to connect calls between users. Mobile Telephone Switching Office (MTSO) /Mobile Switching Center (MSC) Mobile Switching Center (MSC) is commonly designed as a typical ISDN switch with some added functionality and signaling required to support the user mobility.
The primary responsibility of the MSC is establishing and tearing down of the communication links between mobiles and their fixed landline counterparts. The MTSO interconnects the cellular network to the PSTN (public switched telephone network) for connection to the local center office and long distance toll centers. It provides all Central Office (CO) types of functions such as switching, networking, call processing, call statistics, and billing for the cellular network. The MTSO coordinates all of the base-station activities such as channel assignments for users in each cell.
It controls handoff decisions, timing, power control, it routes signals and voice to and from the PSTN, and it performs administrative functions such as billing and maintenance, diagnostic testing, and alarm monitoring. * Data-based Systems Data based systems are registers that control mobile subscriber services and contain the records and stored information related to mobile subscribers and equipment. Home Location Register Home Location Registry (HLR) is a database containing permanent and semi-permanent data associated with individual subscriber. Logically, there is only one HLR per network.
The information stored in the HLR is the customers International Mobile Service Identification Number (IMSI), service subscription information, supplementary services, current location of the subscriber, etc. Since HLR is queried whenever there is a need to establish a connection, its access time has to be kept short. For that reason, HLR is frequently incorporated as a part of MSC. Also every attempt is made to minimize the amount of information stored in HLR. HLRs can be deployed both as separate, stand-alone entity, or internal to an individual MSC.
One HLR usually provides service to many MSCs in a single network. If an HLR is deployed internal to an MSC, other MSCs in the network communicate with that MSC as if it were a stand-alone HLR. The network can support multiple, distinct HLRs serving specific geographic areas or based upon some other division of subscribers. However, the HLR is still considered to be a single logical entity in a cellular network meaning that single subscriber profile record cannot exist in more than one active HLR. Visitor Location Register
Visitor Location Registry (VLR) is a temporary database that keeps the information of the users within the service area of a given MSC. Usually there is one VLR per switch. The main task of the VLR is to reduce the queries of HLR. When the mobile registers on the system, its information is transferred from HLR into VLR of the serving MSC. This way, most of the call processing tasks that require user information are handled locally, (i. e. by serving MSC and its VLR). As subscriber is moved from one serving area to the other, the data is exchanged between the appropriate VLRs.
Unlike HLR, which has global scope, the VLRs serve particular geographic area. In essence one can think of GSM network as being geographically partitioned by service areas of different VLRs. Like HLR, the VLR was originally designed as a separate network component. Due to the large amount of information that needs to be exchanged between MSC and VLR, VLR is frequently integrated as a part of MSC. Authentication Center The Authentication Center (AUC) is usually an integral part of HLR responsible for ciphering and data encryption.
GSM standard specified very elaborate encryption algorithms from its inception. Since GSM was designed with European market in mind, it used advanced military encryption algorithms known as A5. Use of these algorithms created export problems to countries outside of Europe. The Authentication Center (AC) represents the authentication functions used to verify and validate a mobile station’s identity and to prevent fraudulent access to cellular networks by phones illegally programmed with counterfeit mobile identification number (MIN) and electronic serial number (ESN).
The functions do not require subscriber intervention and are independent of the air interface protocol used to access the network. A successful outcome of authentication occurs when it can be demonstrated that the MS and network possess identical results of an independent calculation performed both in the MS and in the network. The AC is the primary network entity responsible for performing that calculation based on a set of complex mathematical algorithms. ACs are usually implemented as part of the HLR. Equipment Identity Register The Equipment Identity Register (EIR) represents the database repository for mobile equipment-related data.
The EIR is the database of the electronic serial numbers (ESNs) of mobile equipment along with the status of that equipment. The EIR identifies stolen or fraudulently contained phones that transmit identity data that does not match with information contained in either HLR or VLR, and assists in preventing those phones from being used to access network services. GSM systems are equipped with Equipment Identity Registry (EIR). Each mobile has a unique International Mobile Equipment Identity (IMEI) number. The EIR is a database that maintains three separate lists: 1.
White list – is the list of all approved mobile types. A part of mobiles IMEI indicates its type. When the call is established, the two numbers are compared and the service can be granted only if the mobile type is on the white list. 2. Black list – is the list of mobile IMEIs that are barred from the service on the GSM network. When the call is to be established, mobile’s IMEI is compared with entries in the black list and if the mobile is “black listed”, its access is denied. Black list prevents stolen or seriously malfunctioning mobiles to access the network. 3.
Gray List – is the list of mobiles that are tracked within the system. If the mobile’s IMEI is on the gray list, some additional information about its behavior during the call are logged by the system. * Radio Systems The Radio System is a network entity that interfaces the mobile station to the network via the air interface. It consists of the following two separate subsystems: BTS Cabin/Shelter Room BTS DC POWER SUPPLY UNIT BATTERY BACKUP MAINS POWER PANNEL BTS Cabin/Shelter Room Mains Power Panel BTS DC Power Supply Unit Battery Backup BTS ROOM Antenna Systems & Radio Transceivers
Usually antenna systems and radio transceivers on one base station are called Base Transceiver System (BTS). The primary functions of the BTS are to: * Handle the physical reception and transmission of the correct radio frequency (RF) signals determined by the BSC to and from mobile handsets or terminals * One BTS covers one or more than one cell. * Capacity of BTS depends on no of Transceivers. * Separate the received signals into their respective voice channels (conversations) by combining the correct time slots or coded messages * BTS is connected to BSC via A’bis interface Transmission rate on A’bis is 2 Mbps (G. 703) * Interface between MS & BTS is called Air I/f. * Transmission rate on Air interface is 13 Kbps. * Send these signals to the BSC for compression * Change to another voice channel when directed to hand-off by the BSC * Convert voice channels back to analog, combine multiple voice channels, up-convert to IF frequencies, filter, and amplify for transmission of signals to mobile subscribers. BSC Base Station Controller The Base Station Controller (BSC) may be located with the BTS, near or next to the Mobile Switching Center (MSC), or combined with the MSC.
The BSC manages the radio resources for the BTSs and some BSCs can control up to 100 or even over 250 BTS (vendor specific). Its primary functions include: * Determining when sector or cell hand-offs are to occur * Determining which frequency and time slot or code is to be used for the cell that the mobile user is moving to * Translation of the 13kbps voice channel to a 64bps channel used by the land-based PSTN, thereby decompressing the voice channels received from the BTS before sending to the MSC, and compressing the voice channels received from the MSC * Operation, Administration and Maintenance System
External networks are integral elements in mobile telecommunications network models. They represent interconnections between the mobile network and the PSTN or other networks. PSTN The Public Switched Telephone Network (PSTN) is a network completely separate from the mobile telecommunications network. It refers to the regular wire line telephone network that provides service to the general public. It is important and is mentioned here because the interface between the MSC and PSTN allows call origination from mobile phones to wireline phones and call termination from wireline phones to mobile phones.
ISDN The Integrated Service Digital Network (ISDN) is also a network completely separate from the mobile telecommunications network. It refers to the wire line network that provides enhanced digital services over special digital transmission lines to special digital terminals. Computer terminals and switching equipment employ digital adapters that interpret the ISDN digital signals to provide high-speed and high-bandwidth services commonly access the ISDN. The interference between the MSC and the ISDN represents the capability to originate calls from the mobile phones to destinations within the ISDN (e. . , voice mail systems) and to terminate calls from the ISDN to mobile phones. * Mobile Subscriber Unit Mobile Station Unit Block Diagram The mobile unit consists of a control section, a transceiver, a logic unit, and a mobile antenna. The transceiver utilizes a frequency synthesizer circuit which is able to tune any of the channels allocated by the FCC the mobile is designed e. g. in the case of AMPS, it is able to tune the transmitter to any of 832 full duplex FM channels between 824 to 849 MHz and the receiver between 869 to 894 MHz in the cellular range.
The control section does system operation while the transceiver is responsible for transmitting and receiving information via the mobile antenna. The mobile antenna is connected via a duplexer to the transceiver so it is able to transmit and receive RF energy. The logic unit interprets subscriber actions and system commands. It also manages the transceiver and control unit. Each mobile is assigned a 10-digit number similar to a conventional telephone number, and a 32 bit binary serial number that uniquely identifies it in the cellular system.
This number is factory programmed, cannot be dialed, and is secured against illegal alteration. It is commonly referred to as the equipment serial number (ESN). Whenever a mobile is turned on but not in use, the mobile’s control unit monitors the data being transmitted on a setup channel by the strongest base station. If signal strength becomes marginal as the mobile unit approaches a cell boundary, the mobile control section finds a setup channel with a stronger signal to lock on. In this standby condition, the mobile is ready to make or receive calls. MULTIPLE ACCESS SCHEMES
Multiple access schemes allow many users to simultaneously share a finite amount of radio spectrum. There are several technology types currently used in the mobile wireless industry. The technology types vary in their use of the allocated RF spectrum. In order for systems to live up to the high level of performance, they must support high-capacity call traffic scenarios, location independent high-quality service, and low pricing so that the average income earner can subscribe to the service. Today, mobile communication systems mainly rely on three multiple access schemes: * Frequency Division Multiple Access (FDMA) Time Division Multiple Access (TDMA) * Code Division Multiple Access (CDMA, also known as Direct Sequence Spread Spectrum) Frequency Division Multiple Access Frequency Division Multiple Access (FDMA) is used in conventional analog cellular systems (e. g. AMPS, NMT). The FDMA process assigns discrete frequencies (i. e. channels) to individual users. It is considered multiple access in that a number of users can simultaneously use the system providing there is sufficient spectrum to accommodate each user. Accordingly, the capacity of this system is limited by the amount of available spectrum.
One frequency is used for downlink (from base station to mobile), and the other one is used for uplink (from mobile to base station). The usage of a pair of frequencies enables full duplex communication between the mobile user and base station. An assigned pair of frequencies is commonly referred to as a channel. Channels are assigned to the user on demand. During the call, no other user within the reuse distance can be assigned the same frequency. After the call is completed, the channel is released and assigned to another user in the system requiring the service.
Multiple users receiving service from the cellular system at the same time are assigned different channels; they operate without interference to each other. The FDMA multiple access scheme is illustrated in the following figure. Illustration of the FDMA Concept Some advantages of FDMA access technology: * The complexity is relatively small in comparison to other accessing schemes. * After the assignment of the channel, the call is serviced in a continuous way. This makes this access scheme well suitable for analog modulation types. * Only one user is accommodated per physical channel.
This means that no synchronization between the users is necessary. * Works for Analog signals. Some important disadvantages of FDMA are: * FDMA is a circuit based access scheme. A channel remains assigned to the user over the entire duration of the call regardless of its usage. * Relatively sophisticated filtering circuits are needed for rejection of adjacent channel interference. * FDMA is a relatively costly access scheme since one radio is needed for every user communicating with the base station. * Requires the additional use of guard spaces. * It is inflexible. Time Division Multiple Access
In TDMA based wireless systems, multiple users operate on the same radio frequency. However, they do not communicate simultaneously. Each user is given access to the system resources at a different time. Multiple users operate on the same frequency. Since users are accessing the channel one at a time, the transmission has to be discontinuous. This effectively means that modulation used in TDMA systems must be digital. A technique known as time multiplexing gives the subscriber data contained in each of the time slot assignments momentary access to the entire bandwidth of the RF spectrum in sequential order.
TDMA based communications are conducted in an accumulate and burst fashion. While waiting for the time slot assignment, each user accumulates the portion of the data stream to be transmitted. When the slot is assigned, all accumulated data is transmitted over the channel at a higher rate. The ratio of the channel data rate and user data rate is directly proportional to the number of users sharing the same communication channel. A graphical representation of the TDMA principle is presented below. An Illustration of the TDMA Concept Some advantages of the TDMA scheme are: * It has a relatively low complexity. Because of the discontinuous transmission, the hand-off process is greatly simplified and has improved reliability. In periods when it is not transmitting or receiving, mobiles can perform measurements of the channel and assist in the hand-off process – Mobile Assist Hand-Off (MAHO). * It is possible to allow a different number of slots per frame to different users to accommodate users with different data rate requirements. * Landline networks are TDMA based. This makes the integration of TDMA mobile network somewhat easier. * Requires only carrier in the medium at any time. Throughput high for many members as well. Some disadvantages of TDMA are: * High synchronization overhead is required. * Guard times have to be incorporated in order to minimize the probability of collision between different users. * Only digital modulations can be used. Code Division Multiple Access Code Division Multiple Access (CDMA), which uses a digital spread spectrum transmission scheme, was developed to provide significantly improved spectral efficiency compared to existing technologies. In CDMA, all users in the system operate on the same carrier frequency pair.
One frequency is assigned for the uplink and another frequency is assigned for downlink transmission. However, the data associated with each individual call is coded with a unique code sequence. Upon establishing the call, the user is assigned a code sequence orthogonal to the code sequences of every other user in the system. The user code is correlated against the receive signal to recover only the information specific to that user. The capacity of a CDMA system is governed by the amount of interference in the environment that the receiver can tolerate before it is unable to recover the desired user information.
Since all of the users are operating on the same frequency, co-channel interference is an unavoidable part of the CDMA system operation. It is the orthogonal properties of the coding sequences along with the spreading processing gain that makes communication possible. Some advantages of the CDMA scheme include: * No need for complicated frequency coordination between the users. * Systems implementing CDMA have soft capacity limit – allows a trade off between capacity and quality. * Users with different bit rate requirements can easily be accommodated through variable spreading.
Some disadvantages of CDMA include: * CDMA has a significantly higher complexity relative to other access schemes. * Elaborate power control is essential to eliminate the near-far problem. * Extremely precise timing reference is needed for orthogonal de-spreading. GSM Channel Structure GSM Channel Structure Control Channel Group These are: Broadcast Channel (BCH); Common Control Channel (CCCH); Dedicated Control Channel (DCCH). BCH Group The Broadcast Channels are downlink only (BSS to MS) and comprise the following: – BCCH carries information about the network, an MSs present cell and the surrounding cells.
It is transmitted continuously as its signal strength is measured by all MSs on surrounding cells. – The Synchronizing Channel (SCH) carries information for frame synchronization. – The Frequency Control Channel (FCCH) provides information for carrier synchronization. Broadcast Control Channel (BCCH) – Carries the following information (this is only a Partial list): – Location Area Identity (LAI). – List of neighboring cells which should be monitored by the MS. – List of frequencies used in the cell. – Cell identity. – Power control indicator. – DTX permitted. Access control (for example, emergency calls, call barring). – CBCH description. The BCCH is transmitted at constant power at all times, and its signal strength is measured by all MS which may seek to use it. “Dummy” bursts are transmitted to ensure continuity when there is no BCCH carrier traffic. Frequency Correction Channel (FCCH) This is transmitted frequently on the BCCH timeslot and allows the mobile to synchronize its own frequency to that of the transmitting base site. The FCCH may only be sent during timeslot 0 on the BCCH carrier frequency and therefore it acts as a flag to the mobile to identify Timeslot 0.
Synchronization Channel (SCH) The SCH carries the information to enable the MS to synchronize to the TDMA frame structure and know the timing of the individual timeslots. The following parameters are sent: – Frame number. – Base Site Identity Code (BSIC). The MS will monitor BCCH information from surrounding cells and store the information from the best six cells. The SCH information on these cells is also stored so that the MS may quickly resynchronize when it enters a new cell. CCCH Group The Common Control Channel Group works in both uplink and downlink directions. Random Access Channel (RACH) is used by MSs to gain access to the system. -Paging Channel (PCH) and Access Granted Channel (AGCH) operate in the “downlink” direction. The AGCH is used to assign resources to the MS, such as a Stand-alone Dedicated Control Channel (SDCCH). The PCH is used by the system to call a MS. The PCH and AGCH are never used at the same time. -Cell Broadcast Channel (CBCH) is used to transmit messages to be broadcast to all MSs within a cell, for example, road traffic information, sporting results. Random Access Channel (RACH) Used by the mobile when it requires to gain access to the system.
This occurs when the mobile initiates a call or responds to a page. Paging Channel (PCH) Used by the BTS to page MS, (paging can be performed by an IMSI, TMSI or IMEI). Access Grant Control Channel (AGCH) Used by the BTS to assign a dedicated control channel to a MS in response to an access message received on the Random Access Channel. The MS will move to the dedicated channel in order to proceed with either a call setup, response to a paging message, Location Area Update or Short Message Service. Cell Broadcast Channel (CBCH) -This channel is used to transmit messages to be broadcast to all MSs within a cell. The CBCH uses a dedicated control channel to send its messages, however it is considered a common channel because the messages can be received by all mobiles in the cell. -Active MSs must frequently monitor both BCCH and CCCH. The CCCH will be transmitted on the RF carrier with the BCCH. DCCH Group Dedicated Control Channels are assigned to a single MS for call setup and subscriber validation. DCCH comprises: – Stand-alone Dedicated Control Channel (SDCCH) which supports the transfer of Data to and from the MS during call setup and validation. – Associated Control Channel.
This consists of Slow ACCH which is used for radio link measurement and power control messages. Fast ACCH is used to pass “event” type messages, for example, handover messages. Both FACCH and SACCH operate in uplink and downlink directions. Stand alone Dedicated Control Channel(SDCCH) It is used as an interim channel before final assignment of TCH. SDCCH is used for signaling and Authentication message transfers. Standalone Dedicated Common Control Channel. It is used as a interim channel before final assignment of TCH. It can be called the stepping-stone between BSC and TCH.
The SDCCH, by using less of the cells resource of physical channels, improves efficiency, and provides a useful holding channel for the mobile until speech data needs to be exchanged Associated Control Channels (ACCH) These channels can be associated with either an SDCCH or a TCH. They are used for carrying information associated with the process being carried out on either the SDCCH or the TCH. Slow Associated Control Channel (SACCH) Conveys power control and timing information in the downlink direction (towards the MS) and Receive Signal Strength Indicator (RSSI), and link quality reports in the uplink direction.
Fast Associated Control Channel (FACCH) The FACCH is transmitted instead of a TCH. The FACCH ”steals” the TCH burst and inserts its own information. The FACCH is used to carry out user authentication, handovers and immediate assignment. All of the control channels are required for system operation, however, in the same way that we allow different users to share the radio channel by using different timeslots to carry the conversation data, the control channels share timeslots on the radio channel at different times. This allows efficient passing of control information without wasting capacity which could be used for call traffic.
To do this we must organize the timeslots between those which will be used for traffic and those which will carry control signaling. Logic Channel Group There are two main groups of logical channels, traffic channels and control channels. Traffic Channels(TCH) It carries the voice data. Two blocks of 57bits contain voice data. One TCH is allocated for every active call. While call is in progress if there is degradation in quality of current channel, BTS may shift the communication to another TCH on a different Carrier and/or Timeslot. A full rate TCH carries 13kbps voice data, and half rate TCH carries a 6. kbps data. The standards and actual implementation for Half Rate channel is under development. Conceptually two mobiles share the Half Rate channel. Traffic Channel carries the voice data, two blocks of 57 bits contain voice data, and One TCH is allocated for every active call. While call is in progress if there is degradation in quality of current channel, BTS may shift the communication to another TCH on a different Carrier and/or Timeslot, A full rate TCH carries 13 kbps voice data, and half rate TCH carries a 6. 5 kbps voice data. Speech Channels
Speech channels are supported by two different methods of coding known as Full Rate (FR) and Enhanced Full Rate (EFR). Enhanced Full Rate coding provides a speech service that has improved voice quality from the original Full Rate speech coding, whilst using the same air interface bandwidth. EFR employs a new speech coding algorithm and additions to the full rate channel coding algorithm to accomplish this improved speech service; however, it will only be supported by Phase 2+ mobiles onwards. CDMA Channels Physical Channel Physical channels are described in terms of a wideband RF channel and code sequence.
As defined in IS-95, each RF channel is 1. 2288 MHz wide. For each RF channel, there are 64 Walsh sequences (W0 through W63) available for use on the forward link. These Walsh sequences are commonly referred to as CDMA channels (though this is not correct for the uplink). Logical Channel Divisions on the physical channel that carry specific types of information are known as logical channels. Logical channels in CDMA are divided into two categories: Traffic Channels and Control Channels. For the forward link there are three types of Control/Signaling channels and one Traffic Channel (per user).
For the Reverse Link there is one type Signaling Channel and one Traffic Channel per user. It is important to note that signals on the forward link are identified by Walsh codes, however, signals on the reverse link are identified by Long Codes. Summary of Codes In discussing CDMA modulation, several different PN sequences or “codes” are bantered about incessantly. In attempting to make sense out of CDMA modulation, it is helpful to know the relative length (time period) of these codes as well as what they are used for. PN Long Code The Long Code is a PN sequence that is 242 – 1 bits (chips) long.
It is generated at a rate of 1. 2288 Mbps (or Mcps) giving it a period (time before the sequence repeats) of approximately 41. 4 days. The long code is used to encrypt user information. Both the base station and the mobile unit have knowledge of this sequence at any given instant in time based on a specified private “long code mask” that is exchanged. The generation of a Long Code is governed by Long Code Mask. A long code mask is a 42 bit code which define the initial values used by the long code generator. Knowledge of this long code mask allows the base station or mobile user to generate the same PN Long Code.
Generating the same long code (synchronized in time) at both end of the link allows information to be encrypted and decrypted. A unique and private, long code mask (thus, PN long code) is assigned to each CDMA user. This code is referred to as a “user mask”. The user mask is exchanged between the mobile and the serving cell(s)/sector(s), which allows user traffic data to be encrypted on both the forward and reverse links. A different long code mask is used to generate the long code for encryption and decryption of Access and Paging information – more on this later. PN Short Codes
The Short Code is a PN sequence that is 215 bits (chips) in length. This code is generated at 1. 2288 Mbps (or Mcps) giving a period of 26. 67 ms. This code is used for final spreading of the signal and is transmitted as a reference known as the “Pilot Sequence” by the base station. All base stations use the same short code. Base stations are differentiated from one another by transmitting the PN short code at different “offsets” in absolute. This time offset is known as a “PN Offset”. All base stations and mobiles have knowledge of this code, however, mobile units do not have initial knowledge of absolute time.
Mobile units initially search (in time) until they synchronize with a pilot code transmitted by a base station. The base station then conveys timing information to the mobile. Walsh Codes CDMA defines a group of 64 orthogonal sequences, each 64 bits long, known as Walsh Codes. These sequences are also referred to as Wash Functions. These codes are generated at 1. 2288 Mbps (Mcps) giving them a period of approximately 52 ? s. These are used to identify users on the forward link. For this reason they are loosely referred to as CDMA channels.
All base stations and mobile users have knowledge of all Walsh codes. Putting All Together : CDMA Channels Forward Link (Downlink) The logical channels for the Forward Link must provide identification of the Base station, timing and synchronizing of the transmissions between the base station and mobile station, “hailing” of mobile units in the area, and the voice/data transmission from the base station to the mobile unit. The forward link is comprised of: 0 The Pilot Channel, 1 Up to one Sync Channel, 2 Up to seven Paging Channels, and 3 Up to 55 Traffic Channels.
Forward Link Channel Assignments Pilot Channel The Pilot Channel allows a mobile station to acquire the timing of the Forward Traffic Channel – user information. It provides a phase reference for coherent demodulation and provides a means for signal strength comparisons between base stations, which is used to determine when to handoff. It consists of the unmodulated final spreading sequences (PN short codes). The Pilot signal is transmitted continuously on Walsh 0 by each CDMA base station at the transmitter (cell/sector) level. Sync Channel
The Synchronization Channel is an encoded, interleaved and modulated spread spectrum signal that is used with the Pilot Channel to acquire initial system time and synchronization. The sync channel is always transmitted on Walsh 32. Paging Channel The Paging Channel is used for transmission of control information to the mobile. When a mobile is to receive a call it will receive a “page” from the base station. Up to seven (7) channels may be configured for paging depending on the expected demand. Page channel messaging to each user takes place in an 80 ms “slot”.
The 80 ms slots are grouped into cycles of 2048 slots (cycle duration 163. 84 s) referred to as maximum slot cycles. The base station can limit the maximum slot cycle used by the mobile. The mobile randomly picks a “slot cycle index” and informs the base station of its choice when it registers. The mobile now only monitors the Page channel during its assigned 80 ms slot defined by: Slot Cycle = 1. 28 x 2 SLOT_CYCLE_INDEX (in seconds) where:SLOT_CYCLE_INDEX is {0 … 7} That is to say… for a slot cycle index of 5, the mobile “powers up” and monitors the Page channel for 80 ms once every 1. 28 x 25 = 40. 96 seconds.
This process of periodic monitoring allows considerable power savings by the mobile unit. Traffic Channel The Traffic Channel or Traffic Channel Element (TCE) carries all the phone calls (voice or data signal) from a given base station to all the mobile units active in the coverage area. Each user has a dedicated TCE, and corresponding Walsh code, on the down link. The forward traffic channel message consists of user voice (or data), power control data, and error correction bits. The message is transmitted as a series of traffic frames. The traffic channel may also carry signaling information with or in place of user voice (or data).
A Walsh code is assigned by the base station for each Traffic Channel in use. Power Control Sub-Channel A Power Control Sub-Channel is continuously transmitted on the forward traffic channel as part of the traffic frame. Information on this channel commands the mobile unit to adjust its transmitted power + 1 dB every 1/16 of a speech frame (800 times per second). Reverse Link (Uplink) The logical channel requirements of the reverse link must provide for the identification and access request by the mobile unit to the base stations in the area and the voice/data transmission from the mobile unit to the base station.
The reverse link is composed of: 4 Access Channels and 5 Traffic Channels. These channels share the same CDMA center frequency on the reverse link (a different frequency is used for forward link transmissions). The total number of channels is determined by base station activity. The example in the figure shows 55 Traffic Channels available for all reverse links at a given base station in accordance with the previous forward link channelization discussion. In actuality, an individual subscriber unit is limited to one access channel and one traffic channel. The reverse link apability of a given base station is limited by the number of traffic channels assigned (up to 55) and up to seven (7) access channels (correlating to a maximum of 7 paging channels). Note that a mobile does not “tie up” an access channel, it only borrows it for a short amount of time. Reverse Link Channel Assignments Access Channel The Access Channel is used for the transmission of control information to the base station. When a mobile is to place a call it uses the “access” channel to inform the base station. This channel is also used when responding to a “page”.
Each Access Channel is identified by a distinct “Access Channel Long PN Code “. An Access Channel is selected randomly by the mobile unit from the total number of access channels available from the serving cell/sector. Traffic Channel The Traffic Channel for the reverse link is identical to the forward link Traffic Channel Element in function and structure. Each traffic channel is identified by a “User Long PN Code” which is unique to each CDMA user. CELL CONCEPT Typically the network coverage area is always large, several BTSs are used to cover that area (as shown in figure).
The network coverage to the user is provided by the BTS that belongs to that particular cell site. But when the user moves out of that cell site, there is a problem of network coverage. To handle this situation, the concept of hand-off is used to support the subscriber mobility. Mobility management is the primary set of functions supported by the network to enable this subscriber mobility. Mobility in cellular systems refers to the ability of the network to track a subscriber’s status and location and continue providing service without interruption for the subscriber moving between ells during the call. This process is called as hand-off. Types of Hand Off’s * Soft Handoff – The condition where two cells are in simultaneous communication with the mobile is called Soft Handoff. Soft Handoff will continue until the pilot signal from one of the contributing cells drops below a predefined threshold (TDROP ). At that time the call will be transferred to the remaining cell. * Soft Soft Handoff – SoftSoft Handoffs are identical in function and process to that of the soft Handoff, however, SoftSoft Handoffs entail the simultaneous serving of a mobile unit by three cell sites.
Three is the maximum number of serving signals due to mobile (RAKE) receiver specification. * Softer Handoff – Softer Handoffs are identical in function and process to that of the soft Handoff, however Softer Handoffs entail the simultaneous serving of a mobile unit by two sectors of the same cell. * Soft Softer Handoff – Soft Softer Handoffs are identical in function and process to that of the Soft Handoff, however, SoftSofter Handoffs are the simultaneous serving of a mobile station by the original sector, an adjacent sector, and an adjacent or neighboring cell. Hard Handoff – A hard Handoff occurs when a CDMA call is transferred from one base station to another base station transmitting on a different carrier frequency. Hard Handoff is analogous to the Handoff procedure that takes place in standard AMPS Cellular. The mobile unit will initially seek to perform a soft Handoff. If the cellular network cannot perform a soft Handoff, a hard Handoff is necessary * CDMA to Analog Handoff – If there are no CDMA channels to Handoff to, then the call would be handed off to an available analog channel at the serving base station and switched to the analog mode of processing. From hat point on, the call will be handled as any other analog call at that base station. * Mobile Assist Handoff – GSM implements Mobile Assisted Handoff (MAHO). In MAHO systems, the mobile assists in the process of handoff by helping the base station in the decision on the best handoff candidate. GSM mobiles provide the serving base station with the strength and quality measurements of the channels from surrounding sites. Mobile measurements are not the only measurements used to determine the best handoff candidate. Signal strength, signal quality and timing advance information are gathered on the BTS side as well.
BTS AND ANTENNA BTS In essence, Base Transceiver Station (BTS) is a set of transceivers (TRX). In GSM, one TRX is shared by as many as eight users in TDMA mode. The main role of the TRX is to provide conversion between the digital traffic data on the network side and RF communication between the mobile and GSM network. On the network side, the BTS separates the mobile’s data and signaling and sends them back to the Base Station Controller. Communicating with the mobile, the BTS performs a reverse function of combining user data and signaling and sends them on a single RF channel.
A single GSM BTS can host up to 16 TRXs. Depending on the application, BTSs can be macro or microcell, omnidirectional or sectorized, etc. Antenna Selection Criteria Antenna plays an important role in the wireless communication technology. Antenna is a passive conducting device that radiates electromagnetic waves for the corresponding electrical signals. Antennas are of different types and sizes which can be used for different types of applications. The radiation patterns and gains of antenna vary according to the type of antenna used. Following table gives the brief explanation of the variation n beam width and gain with respect to the antenna type. As the antennas come of different shapes and sizes depending upon the type of application, a proper antenna has to be used when it comes to using it in using a cellular network since there are constraints on valuable resources like bandwidth and cost. The standard antenna that is used in cellular network design is shown below. The beam width varies according to the coverage requirements. The gain decides the output power and hence the penetration of the signal into the region i. e. high gain antenna can be used to provide high output power whose penetration in terms of distance will be very high, and network can reach to remote areas with less signal fading. The following diagram shows the three dimensional representation of signal radiation pattern. As explained earlier, the antenna selection plays an important role in network planning. The antenna type varies depending upon the coverage and capacity requirements. Hence different types of antenna have to be used for different regions like urban, suburban and rural. 1) Antenna Selection for Urban Areas: ) In high-subscriber areas, the distance between stations is about 300-500m, and the title angle should be 10-190. To satisfy these needs, we suggest a ±450dual polarized directional antenna with fixed 90 electrical downtilt and 650beam width. Working with mechanical down-tilt mounting kits of 150, the antenna secure that the pattern in horizontal directional remains constant when the main beam tilts 10-190. The wide application of the antenna indicates that it can satisfy coverage need in high density urban areas. b) In medium-subscriber urban areas, the distance between stations is bigger than 500m and downtilt angle should be 6-160.
In this case, ±450dual polarized directional antenna with fixed 6o electrical downtilt and 650beam width can secure consistent half power beam width when the main beam tilts 6-160 ,and satisfy coverage need in medium density urban areas. c) In low-subscriber urban areas, the distances between stations are large and the tilt angle should be 3-150. In this case, ±450 dual polarized directional antenna with fixed 30 electrical downtilt and 650beam width can secure consistent half power beam width when the main beam tilts 3-150 and satisfy coverage need in low density urban areas. ) Antenna selection for Small Town Areas: a) In these small subscriber areas, out attention should be paid to coverage. In this case, we can select single polarized antennas (triple or dual section) featured by higher gains (17dBi) and larger horizontal beam width (65°, 90°). b) Highway dual-directional antenna. If the subscriber is rather small along highway/railway, we can select dual-directional antennas, a modification of Omni-directional antenna with 70°beam-width and 14dBi gain. 3) Highway & town antennas:
In the low-subscriber areas where both highway/railway and a nearby town should be covered, weak directional antenna 900 with 100 vertical beamwidh is used to satisfy the coverage need. Antennas Used As explained earlier, the different types of antenna are used for different regions e. g. urban, suburban and rural. In the network planning for Jaipur, antennas which have been used are of beam widths: 330 (Urban), 650 (Sub-urban), 900 (Rural). These are the general beam width selections, yet the selection also depends on capacity requirements also.
Different types of antennas which have been used in the planning of network in Jaipur are: 1. 2. 3. PROPAGATION MODEL Okumura Propagation Model The Okumura model is based on detailed analysis if exhaustive drive tests measurements made in Tokyo and its suburbs in late 1960’s and early in 1970’s. The collected date included on numerous VHF, UHF microwave signal sources, both horizontally and vertically polarized at a wide range of heights. The measurements were statistically processed and analyzed with respect to almost every imaginable variable.
This analysis was distilled into the curves above, showing a median attenuation relative to free space loss Amu(f, d) and correlation factor Garea (f, area ), for BS antenna height ht=200m and MS antenna height hr=3m. Okumura has served as the basis for high level design of many existing wireless systems, and has spawned a number of newer models adapted from its basics concepts and numerical parameters. SOFTWARES USED Google Earth Google Earth is the software which gives geographical view of any portion of the earth in 3-Dimension (3D) fashion.
It uses satellite imagery, maps and layer upon layer of other information which allows seeing the entire portion of the earth, the countries, states, cities, streets, restaurants, and local points of interest, airports, geographic information, 3D buildings and many more things. Google Earth has added advantage that it also shows the population of any place on the earth and gives the geographical view of the particular place which shows the density of population of that place. Hence planning the sites in Google Earth. guides the area is urban, suburban or rural. It also has scale which gives the distance between two points on the earth hence distance between neighboring BTS can be calculated, which is important in coverage calculation. MapInfo also gives only the clutter and terrain information but Google Earth gives you clutter, terrain as well as the pictorial view of the desired place. Because of this feature of Google Earth, it is better to plan the sites from Google Earth than from the MapInfo. Information can be exported from MapInfo to Google Earth e. . different cosmetic layers like location and orientation of BTS can be transferred to Google Earth. Also the data from Agilent Wizard, like Forward link and Reverse link parameters, Antenna parameters can be exported to MapInfo, which then can be transferred to Google Earth. The Google Earth also supports different display features e. g. colour layers of the selected regions can be made partly transparent so that you can view both the colour as well as the geographical 3D-view of the place. Agilent Wizard
Agilent Wizard RF Engineering Software is a state-of-the-art engineering tool that can simplify your RF engineering work. Through its Geographical User Interface, many time-consuming, tedious, tasks retransformed into simple point and click operations. As an engineer or engineering manager, the primary task is engineering. It is a comprehensive, easy-to-use software package. It can be run in a fully networked environment or in a stand-alone mode. When installed on the network, the related data can be easily shared.
WIZARD provides the RF engineer with a comprehensive set of analyses and display capabilities. Beyond the typical capabilities of coverage and interference analyses, WIZARD gives the ability to use drive test data to automatically optimize the propagation predictions. As a result, coverage and interference predictions are more accurate. Site placement, power levels, and antenna configurations can all be set with greater confidence. These, along with channel display and edit capabilities, greatly simplify frequency planning. MapInfo Professional
MapInfo Professional is a Geographic Information System software product. MapInfo Professional has the ability to combine and display data from different formats, sources, and projections on one map. The software is also capable of overlaying raster and vector on the same map. The software also allows you to make raster layers semi-transparent, so they can be layered among the other data layers and not just serve as backdrops. The basic file components for a MapInfo Professional data set are established by the two basic environments for working in MapInfo; “Browser view” and “Mapper View”.
As with most other GIS packages, several files are required to allow the user to open a data set for viewing within MapInfo Professional. The most basic view would be the browser view only. This environment provides storage of attribute or objects data and is represented like a spreadsheet. Only data can be seen in a tabular format with this environment, no geographic information is available at this point. Minimum files required for the basic MapInfo browser environment: * . DAT (The file which stores the attribute data) * .
TAB (The ASCII file which is the link between all other files and holds information about the type of data file ) To view geographic information (the graphic representation of data) in MapInfo Professional, two additional files are required and added to the basic requirements for simply viewing data. Minimum files required for viewing a map with the data: * . ID (Stores information linking graphic data to the database information) * . MAP (Stores the graphic and geographic information needed to display a map on the users screen) * . IND (Optional index files for tabular data).
Hence the basic file set for viewing data and its graphic representation within MapInfo Professional requires a minimum of four files, the *. DAT, *. TAB, *. ID and *. MAP. Landmark can be made on the map provided the latitude and longitude of the landmark is known. Also different layers can be added to the map. e. g. in Jaipur map, rail and road information, site name can be added and all can be seen at the same time by using layer control option viewable. Also the landmarks and site names can be editable with the help of layer control option.
One of the best mechanisms that MapInfo has is the import/export mechanism. MapInfo Interchange Format is a map and database exporting file format of MapInfo software product. The MIF-file filename usually ends with . mif-suffix. Data can be imported from or exported to the Agilent Wizard. Also sites can be created in the MapInfo with the help of excel sheet having site name, latitude, longitude, azimuth, beam width, radiation center, PN, mechanical down tilt etc. This file is a . text file, which can be converted into . TAB file with the help of tool manager having option as a cell tool.
This . TAB file when opened, gives the location of the site and the site name with the number of sectors each site has and the beam width. This information can be exported to Google Earth with the help of ‘MI2google’ option. Agilent Wizard and Google earth does not have direct connection as an import/export between them. Hence MapInfo is the connecting software between Agilent Wizard and Google Earth. Network Planning The aim of the project is to form a wireless network in Chandigarh and its outskirts. The network planning procedure is very complex.
It requires knowledge of different parameters which includes number of BTS required, their positions, PN sequence of each BTS, antenna used, their azimuth angel and mechanical and electrical tilt. Also there should be provision made for future growth of this wireless network. So considering all these parameters network has to be planned. Calculations about the number of BTS (Step 1) To form a wireless network in any given area, the basic component required is BTS (Base Transceiver Station) and the first step is to find the approximate number of BTS required there.
There are two basic parameters required to calculate the required number of BTS. They are. (i) Capacity (ii) Coverage (I) Capacity: – It depends upon the number of subscribers in that area. Its calculation can be carried out in following way One sector of BTS can support 25 Erlangs of traffic. i. e. 1 sector of BTS => 25 Erlangs Generally in practice 3-sector antenna is used. 3 sector BTS => 25*3=75 Erlangs. Relation between number of subscribers and total number of BTS is given as:- Total Erlangs per BTS per user*number of carriers per BTS = number of subscribers| Here assumption can be made that 0. 4 Erlangs are used per subscriber. And for each BTS we can use more than one carrier i. e. different frequencies (but carriers cannot be more than three) Now according to the business department of Reliance Communication there are approximately 400,000 mobile subscribers of Reliance in Jaipur and its outskirts. This can be divided as; (i) 10000 subscribers are in rural area In rural area 1 carrier per BTS are assumed. 75*1/0. 04*(number of BTS in rural area) = 10000 Hence number of BTS in rural area = 6 (ii) 50000 subscribers are in suburban area. In suburban area 2 carriers per BTS are assumed. 5*2/0. 04*(number of BTS in suburban area) = 30000 So number of BTS in rural area = 9 (iii) Remaining 360,000 subscribers are in urban area. In urban area 3 carriers per BTS are assumed. 75*3/0. 04*(number of BTS in urban) = 360,000 So number of BTS in rural area = 69 Hence total number of BTS is 6+9+69=84. It can be shown in table as given below Area Type| Number of carriers used| Population| Number of BTS| Rural| 1| 10000| 6| Suburban| 2| 30000| 9| Urban| 3| 360000| 69| 400000 | 84| So above calculation shows the requirement of number of BTS’s required in Chandigarh as per the capacity.
There is one more parameter that has to be taken into account i. e. coverage. (II) Coverage: – It depends upon the total geographical area to be covered by all the BTS. Coverage of any BTS depends upon the physical parameters like clutter and terrain present in that region. Clutter is an obstacle for RF (radio frequency) waves like build