cmc coursefile

IV Year B.Tech. ECE - II Semester CELLULAR AND MOBILE COMMUNICATIONS

UNIT ICELLULAR MOBILE RADIO SYSTEMS : Introduction to Cellular Mobile System, Performancecriteria, uniqueness of mobile radio environment, operation of cellular systems, Hexagonal shaped cells,Analog and Digital Cellular systems.UNIT IIELEMENTS OF CELLULAR RADIO SYSTEM DESIGN : General description of the problem, conceptof frequency channels, Co-channel Interference Reduction Factor, desired C/I from a normal case in aomni directional Antenna system, Cell splitting, consideration of the components of Cellular system.UNIT IIIINTERFERENCE : Introduction to Co-Channel Interference, real time Co-Channel interference, Co-Channel measurement, design of Antenna system, Antenna parameters and their effects, diversityreceiver, non-co-channel interference-different types.UNIT IVCELL COVERAGE FOR SIGNAL AND TRAFFIC : Signal reflections in flat and hilly terrain, effect ofhuman made structures, phase difference between direct and reflected paths, constant standard deviation,straight line path loss slope, general formula for mobile propagation over water and flat open area, near andlong distance propagation antenna height gain, form of a point to point model.UNIT VCELL SITE AND MOBILE ANTENNAS : Sum and difference patterns and their synthesis, omnidirectional antennas, directional antennas for interference reduction, space diversity antennas, umbrellapattern antennas, minimum separation of cell site antennas, high gain antennas.UNIT VIFREQUENCY MANAGEMENT AND CHANNEL ASSIGNMENT : Numbering and grouping, setupaccess and paging channels channel assignments to cell sites and mobile units, channel sharing andborrowing, sectorization, overlaid cells, non fixed channel assignment.UNIT VIIHandoff, dropped calls and cell splitting, types of handoff, handoff invitation, delaying handoff, forcedhandoff, mobile assigned handoff. Intersystem handoff, cell splitting, micro cells, vehicle locating methods,dropped call rates and their evaluation.UNIT VIIIDIGITAL CELLULAR NETWORKS : GSM architecture, GSM channels, multiplex access scheme ,TDMA, CDMA.

LESSON PLAN

SUB:cellular and mobile communication BRANCH:ECE

CLASS:IV B.Tech,IISEM

No of classes:60

NAME OF THE FACULTY:J.sofia priya dharshini

UNIT I:CELLULAR MOBILE RADIO SYSTEMSIntroduction to Cellular Mobile System, Performancecriteria, uniqueness of mobile radio environment, operation of cellular systems, Hexagonal shaped cells,Analog and Digital Cellular systems.

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UNIT II:ELEMENTS OF CELLULAR RADIO SYSTEM DESIGNGeneral description of the problem, conceptof frequency channels, Co-channel Interference Reduction Factor, desired C/I from a normal case in aomni directional Antenna system, Cell splitting, consideration of the components of Cellular system

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UNIT III:INTERFERENCEIntroduction to Co-Channel Interference, real time Co-Channel interference, Co-Channel measurement, design of Antenna system, Antenna parameters and their effects, diversityreceiver, non-co-channel interference-different types.

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UNIT IV:CELL COVERAGE FOR SIGNAL AND TRAFFIC Signal reflections in flat and hilly terrain, effect ofhuman made structures, phase difference between direct and reflected paths, constant standard deviation,straight line path loss slope, general formula for mobile propagation over water and flat open area, near and long distance propagation ,antenna height gain, form of a point to point model.

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UNIT V:CELL SITE AND MOBILE ANTENNASSum and difference patterns and their synthesis, omnidirectional antennas, directional antennas for interference reduction, space diversity antennas, umbrellapattern antennas, minimum separation of cell site antennas, high gain antennas.

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UNIT VI:FREQUENCY MANAGEMENT AND CHANNEL ASSIGNMENTNumbering and grouping, Setup access and paging channels channel assignments to cell sites and mobile units, channel sharing andborrowing, sectorization, overlaid cells, non fixed channel assignment.

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UNIT VII:Handoff, dropped calls and cell splitting, types of handoff, handoff invitation, delaying handoff, forcedhandoff, mobile assigned handoff. Intersystem handoff, cell splitting, micro cells, vehicle locating methods,dropped call rates and their evaluation.

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UNIT VIII:DIGITAL CELLULAR NETWORKS GSM architecture, GSM channels, multiplex access scheme ,TDMA, CDMA.

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UNIT-I INTRODUCTION TO CELLULAR MOBILE SYSTEM---------------------------------------------------------------------------------------------------------------------------

OBJECTIVE TYPE QUESTIONS:

1. Limitations of conventional mobile telephone system are -----------------------2. --------is a process of automatically changing frequencies as the mobile unit is moving from one frequency zone to other.3. MTS operation around ---------------------Hzs4. MJ operates at-------------Hz5. MK operates at 450MHz and provide ----------------------channels.6. ----------------------is defined as the maximum no of customers that could be served by one channel at busy hour.7. For MJ system .M0=---------------------customers/cycle8. For MK systems M0=---------------------customers/cycle9. For an average calling time of 1.76 min using 6 channels the offered load for MK system is ---------------------days.10. For an average calling time of 1.76 min using 6 channels the offered load for MJ system is --------------days.11.In setting allocation policy the-----------seeks system which need BW but provides high usage and consumer satisfaction.12.-----------------divide the allocated frequency band into maximum no of channels.13.----------------system reuses the allocated frequency band in different geographic location.14.----------------------generates many codes over a wide frequency band.15.--------------technology reduces the size of mobile transceivers so that they easily fit into the standard auto mobile.16.mobile radio transmission cannot be applied at 10GHzs or above because ---------------------make the medium improper for mobile communication.17.As the no: of carriers per market increases the degradation ------------18.A basic cellular system consists of----------------------19.A mobile telephone unit contains-----------20. ----------------provides interface between the MTSO and mobile units.21. ------------------------------ interfaces with telephone company zone offices controls call processing.22. ------------------connects the 3 subsystems in cellular system23. The---------------carries the voice and signaling between the mobile unit and the cell site.24. --------------------------convey both voice and data between cell site and the MTSO.25. -------------is very hard to judge without subjective tests from users operators.26. The average of CM scores obtained from all the listeners is called ------------.27.Toll qualify voice is around-----------28. The --------------------have to very high to illuminate weak spots with sufficient reception.29. The higher the ---------------the harder it becomes to control interference.30. The blocking problem is ------------for initializing calls at busy hour.31. During Q calls in an hour if a call is dropped and Q-1 calls are completed then the call drop rate is-------------32. The propagation path loss should be -------------------dB/dec.33. ------is inversely proportional to the R 4 where R is the distance measured from transmitter to the receiver.34. A mobile radio signal r(t) can be automatically characterized by the components -----and---------------35. ----is also called multi path fading in the mobile radio environment.36. The propagation path loss---not only with frequency but also with distance.37. The noise figure is defined as----38. The receiver scans -set up channels are designated among the 416 channels.39. When the mobile user turns off the TX ,a particular signal called---------transmits to the cellulite.40. GSM is abbreviated as---------------------

ANSWERS 1. limited service capacity, poor service performance, insufficient freq spectrum utilization2.hand off3.40MHzs4.150MHzs5.126. Frequency utilizing measurement7.538.379.9.3310.6.5111. FCC12. SSB13. Cellular14.speed spectrum of freq hopped15.LSI16.severe propagation path loss, multi path fading rains activity17.increases18.mobile unit, cellulite,MSTO19.control unit a transceiver, antenna system20.cellsite21.MTSO22.radio and high speed23.radio link24.micro radio links or T carriers25.voice quality26.mean opinion score27.MOS>=428.Transmitted power29.Transmitted power30.0.0231.1/Q32.increases33.4034.received carrier power35.local mean,rayleigh fading36.rayleigh fading37. (max possible s/N ratio)/(actual S/N ratio at output)38.2139. signaling tone40.global system for mobile

DESCRIPTIVE TYPE QUESTIONS:

1.Explain the limitations of conventional Mobile telephone systems. How are they overcome by cellular systems?

2.Explain truncking efficiency.

3.Explain the factors used to measure the service quality of a cellular system.

4.Discuss the mobile radio transmission medium.

5.Explain the operation of cellular systems.

6.Explain about planning of cellular system in detail.

7.Briefly explain the evaluation of the analog and digital cellular mobile systems.

8.Explain the necessity of cellular concept.

UNIT-2 ELEMENTS OF CELLULAR MOBILE RADIO SYSTEM DESIGN


1. The maximum number of frequency channels per cell N is closely related to _________ in the system.2. The offered load can be derived as___________3. Users in different geographic locations simultaneously using the same frequency channel is called_____________.4. Frequency reuse can drastically increase_________.5. Frequency reuse in the _________ domain results in the occupation of the same frequency in different timeslots.6. The frequency reuse distance D can be determined from D=_______R7. For k=7,D=__8. If all the cell sites transmit the same power then k _______ and frequency reuse distance D______.9. When K is too large, the number of channels assigned to each of k cells become________.10._________ is a function of q.11.q in terms of D and R ____.12. When the ratio q increases,cochannel interference___________.13.The separate D is a function of________ and__.14. In a fully equipped hexagonal shaped cellular systems, there are always _________ cochannel interfering cells in the first tier.15. Normal cellular practice is to specify C/I to be _________.16. After cell splitting, new cell radius=_________.17. The cell splitting for which the installation of every new split cell has to be planned ahead of time is known to be_________.18. The algorithm for ________splitting cell sites is a tedious job.19. The antenna patterns seen in cellular systems are the patterns seen in free space.20. If the front to back ratio of a directional antenna is front to be 20 db in freespace, it would be _______db at cell site.21._______________ can reduce the interference to the neighboring cells and enhance the weak spots in the cell.22.The capacity of the switching equipment in cellular systems is based on the capacity of _____.23.During a busy hour, the number of calls per hour Qi for each of 10 cells is 2000,1500,3000,500,1000,1200,1800,2500,2800,900.Assuming 60% of car will be used during busy hour, then no of customers in the system is____________.24.The maximum calls per hour Qi in one cell be 3000 and an average calling time T be 1.76 min.25.If there are 50 channels in a cell to handle all the calls and the average is 100s per cell, how many calls can be handled in the cell with an average load of 40.3.

ANSWERS:1) Average calling time 2)A=QiT/60 3)Frequency reuse 4)Spectrum efficiency5)time 6)D=√(3k) 7)D=4.6R 8)Increases, increases 9)small 10)cochannel interference 11)q=D/R 12)Decreases 13)KI and C/I 14)six 15)18 db or higher16.old cell radius/2 17. Permanent cell splitting 18.Dynamically 19)Different 20)10 db 21) Antenna tilting 22) Processor associated with switches 23) 28,667 24)88 25)1451 calls per hour

DESCRIPTIVE TYPE QUESTIONS

1. Derive the maximum number of calls per hour per cell and the maximum number of frequency channels per cell. How are they related?

2. Present the concept of frequency reuse channels and frequency reuse distance.

3.With the help of neat diagram explain the N cell reuse pattern for four, seven cell reuse.

4. Derive the C/I in an omnidirectional antenna system

5. What do you mean by cell splitting? How area is divided and explain the different cell splitting techniques.

6. Explain the Handoff mechanisms in mobile systems.

7. Draw the general view of telecommunication and explain the function of each unit.

UNIT-3 COCHANNEL INTERFERENCE


1.___________ leads to co channel interference.2.____________ K>7 would reduce the number of channels per cell and also reduce spectrum efficiency.3. If C/I _________, throughout most of the cell, the system is properly designed.4. If C/N<18db and C/I>18db in some areas, then there is____________ problem5. If both C/N and C/I are less than 18db and C/N~C/I in a given area, then there is _______ problem6. If both C/N and C/I are less than 18db and C/N>C/I in a given area, then there is ________.7. In a k=7 cellpattern, using omnidirectional antenna,C/I is______________.8. In a k=9 cell pattern, using omnidirectional antenna system C/I=______.9. In a k=12 cell pattern, using omnidirectional antenna system,C/I=_________.10. When K_______,the number of frequency channels assigned in a cell must become smaller and the efficiency of applying the frequency reuse scheme__________.11. In a k=7, 3 sector case using directional antennas C/I=___________.12. In a k=7, 6 sector case using directional antennas C/I=________.13. k=________ call pattern system is a logical way to begin an omnicell system.14. One advantage of 600 sectors with k=4 is that they require ________ than 1200 sectors with k=7.15. In a small cells,________ would become uncontrollable.16. On a high hill or high spot, lowering the antenna height does not reduce co channel interference.T/F17. The power reduction caused by decreasing antenna height in a valley is negative in decibels.18. There are two ways to tilt down the antenna parameters _______ and _______.19. To achieve a significant gain of C/I in the interference receiving cell, we should consider using _______in the center of the antenna pattern at the interfering cell.20. The antenna pattern and the antenna height play a major role in justifying_______.21.The umbrella pattern can be achieved by use of a _________.22.Of the most concern for future cellular systems is the large distance interference due to _____.23.The ________pattern might be recommended for every cell site where interference prevails.24.The elevation of the troposheric layer is 10 mi and the propagation distance is about 200 mi.Thus, the angle of the wave propagating through the troposphere layer is__________.25.The_________ in which energy is confined to the immediate area of the antenna is effective in reducing both cochannel and long distance interference.26. The umbrella pattern can be used for an omnidirectional pattern, but not for a directional antenna pattern T/F27.The ________ distance can be shortened by the use of the umbrella pattern.28.Interference at the cell site can sometimes be reduced by using __________,creating a desired pattern in a certain direction.29. In a relatively close spacing two elements are placed as close as ________.30. If the length of the parasite is 5% longer than that of the active one, then the parasite acts as_________.31. If the length of the parasite is shorter than that of the active one, then the parasite acts as__________.32. The ______scheme applied at the receiving end of the antenna is an effective technique for reducing interference.33. For a two branch space diversity, the separation of two antennas at the cell site should meet the requirement__________.

34.______________ is used in the cellular mobile receiver to measure the effective FM receiver sensitivity.35. Adjacent channel interference includes ___________ and __________.36. Adjacent channel interference can be reduced by_____________.37. The filter with__________ slope can help to reduce all the adjacent –channel interference.38. The signal isolation among the forward voice channels is a channel combiner is__________.39. SAT is abbreviated as ______________.40. In mobile cellular systems there is pair of frequencies occupying BW of ------------------

ANSWERS:

1.Frequency reuse 2)Increasing 3)C/I>18db 4)cochannel interference 5)coverage problem 6)coverage problem and interference problem 7)14.47dB 8)19.25dB 9)22.54dB 10) increases, decreases 11)24.5dB 12)29dB13)7 14) fewer cellsites 15) interference 16) True 17)True 18)electronically ,Mechanically 19)notch 20)antenna tilting 21)staggered discone 22)tropospheric propagation 23)umbrella 24)5.70 25)umbrella pattern 26)True 27)Frequency reuse 28)parasitic elements 29)0.04λ 30)reflector 31)director 32)diversity33)h/d=11 34)SINAD 35)Next channel, neighboring channel 36)frequency assignment37)sharp falloff 38)17dB 39)supervisory Audio Tone 40)60kHzs

DESCRIPTIVE TYPE QUESTIONS:

1. Define cochannel interference. How it is measured at the mobile unit?

2. Prove that for hexagonal geometry the cochannel reuse distance is given by Q=√(3N) for N=i2+ij+j2.

3. Illustrate the Real Time Co-channel interference at the Mobile Radio Transceivers.

4. Explain the design of the Omni-directional antenna under the practical case condition for k=4,k=12 and k=7 with all the suitable values and explaining each of them.

5. Explain the design of the directional antenna under the practical case condition for k=4,k=12 and k=7 with all the suitable values and explaining each of them.

6. What is tilting antenna? How can these antenna patterns reduce the co-channel interference?

7. Discuss the diversity schemes for interference reductions at both mobile units and cellsite.

8. What are the different types of cochannel interference? Explain.

UNIT-4 CELL COVERAGE FOR SIGNAL AND TRAFFIC


1. The _____________________ is the angle of wave arrival at the mobile unit.2. Based on snells law, the reflection angle and incident angle are _________.3. In a mobile radio environment, the average cell site antenna height is about 50m,the mobile antenna height is about 3m,and the communication path length is 5 km. The incident angle is___________.4. Average cell site antenna height is about 50m,the mobile antenna height is about 3m,and the communication path length is 5 km.The elevation angle at the location of the mobile unit is___.5.In area to area prediction curves ,the standard deviation represents____________.6.The differences in area to area prediction curves are due to different____________.7._________ represents the signal received as it is received from a flat area affected by different local human made structured environment.8. The effective antenna height is given by ___________9. In mobile radio environment the reflection coefficient av=_________.10.When plotting signal strengths at any given radio path distance, the deviation from the predicte3d values is approximately ___________-.11. The phase difference between the direct path and reflected path is given by__________.12. for pr<p0, ∆ø__________.13. If pr =4p0,then ∆ø 14The path loss obtained due to sizes of leaves, branches,and trunks is called ___________loss.15.__________ loss occurs with respect to the frequency to the fourth power(f-4).16If the situation involves both foliage lossand mobile communications,the total loss would be _________.17)Within I mi intercept, the antenna beamwidth,especially of a high gain omnidirectional antenna is _________ in vertical plane.18.For land to mobile propagation,the antenna ____________ at the cell site strongly affects the mobile reception in the field.19.When the mobile unit is within 1mi intercept, the effect due to the nearby surroundings of the cell site becomes__________.20. The signal received within the near field (d<dF) uses________ formula.21. The signal received within the far field (d>dF uses_______ formula.22. For high site, the_____________ phenomenon would cause the ground wave path to propagate in a non straight line fashion.23)_______________ wave propagation prevails at 800MHz for long distance propagation.24) Gradual bending of the rays due to the changing effective dielectric constant of the atmosphere through which the wave is passing.25)________________ will occur where there are abrupt changes in the dielectric constant of the atmosphere.26)Water content has much more effect than temperature on the __________ of the temperature.27.If the refractive index decreases with height over a portion of the range of height, the rays will be curved downwards and the condition known as _________ will occur.28.____________ appears over the sea and are about 1.5m thick.29.The _____________ is a path which is unobstructed by the terrain contour.30.In obstructive condition, the direct path from the cell site to the mobile unit is obstructed by the ______________ 31.The ___________ loss can be found from a single knife ede or /double knife edge case.32.For 1<=v ,L=______33.With v=0, the diffraction loss l=______34.The total diffraction loss of double knife edge model is___________

35)In mobile to mobile land propagation, the propagation channel acts as a filter with_________________ transfer function.36)When the waves reflected by the surrounding buildings are relatively weak,_____________ is observed.37)If the direct reception is blocked by the surrounding building,____________ fading is observed.38)If the transmitted power is increased by 3 dB,just add _______ to each grid in the signal strength map.39)When the mobile unit is driven a positive slope, the effective antenna _________ if the mobile unit is driving away from the cellsite antenna.40)If the mobile unit is driven down the slope, the effective antenna _________ if the mobile unitis driving away from the cellsite antenna.

ANSWERS:1)ground incident angle 2) same 3)0.610 4)0.570 5)degree of terrain roughness 6)Human made structures 7)path loss slope 8)20 log he/h1 9) -110)8 dB 11)∆ø= β∆d 12)<Π/3 13) =Π 14)Foliage 15)foliage 16)60dB/dec17)narrow 18)height 19)negligible 20)free space 21)mobile radio path loss 22)low-atmospheric 23)Troposheric 24) Troposheric refraction 25)Troposheric reflection 26)dielectric constant 27)Trapping, or duct propagation 28)surface ducts.29)line of sight path 30)terrain contour 31)Diffraction 32)0 dB 33)6 dB 34)L1+L2

35)time varying 36)rician 37)Rayleigh 38)3 dB 39)increases 40)decreases

DESCRIPTIVE QUESITIONS:

1. Discuss Lee model for point to point prediction.

2. Explain the effect of propagation of mobile signals over water.

3. Explain in detail about Long distance propagation.

4. Explain the general formula of received power from real model based on shadow case,direct path and over the water condition in detail.

5. Write short notes on mobile to mobile propagation

6. Explain the factors considered for prediction of path loss for a particular mobile radio environment.

7. Why there is a constant standard deviation along a path los curve?

8. Derive the relation for the maximum coverage distance in mobile environment.

UNIT-5 CELL SITE ANTENNAS AND MOBILE ANTENNAS


1. The outward flow of electromagnetic energy through a given surface is called2. For coverage use _________________ antennas at the cell site.3. Interference reduction ________________ antennas can be used at the cellsite4. In space diversity antennas h/D =5. Each transmitting antenna can transmit signals from 16 radio transmitters simultaneously using

____________.6. If an omnicell site is equipped with up to 90 voice radios ,the______ transmitting antennas must be

used.7. In order to reduce the number of transmitting antennas,_________ can be used which can

combine two 16-channel signals.8. The cochannel interference factor q=D/R =4.6is based on the assumption that the terrain

is________9. The ___________ receiver can tune a channel to one of 333 channels either pon emand or

periodically.10. The______________ antenna is used to page a called mobile unit or to access a call from the

mobile unit.11. ____________ antennas are used at the cell site to receive the same signal with different fading

envelops.12. For controlling energy in a confined area, the____________ pattern antenna can be developed.13. A biconical antenna in which one of the cones is extended to 1800 to form a disk is called __________.

14.______________ antenna can be constructed by vertically stacking a number of umbrella pattern antenna.15. The antenna configuration in which the parasitic element is about ____ times greater than the active element reduces interference in two directions.16. Seperation between two transmitting antennas should be minimized to avoid__________ effects.17. Because of near field disturbances due to close spacing,________ will form in antenna Pattern.18. If the power difference is excessive, use of space diversity will have no effect reducing_______-19. At 850MHz,the separation of eight wavelengths between two receiving antennas creates a power difference of_______.20._________ is often used in cell-site antennas to prevent moisture from entering the cable and causing excessive attenuation.21. The gain of the antenna used at the mobile unit must be limited to _______22. The position of the roof mounted antenna is always_________ than that of the roof mounted antennas23. In_____________- antennas energy can be coupled through glass.24. In high gain antennas, the pattern is suppressed ____________.25. In directional antennas the pattern is suppressed _________26. A two-branch space diversity receiver mounted on a motor vehicle has the advantage of reducing__________27. Inline arrangement of the two antennas produce less fading than the perpendicular alignment does .T/F28. The vertical separation between two space diversity antennas can be determined from the _______________ between the received signals29. Glass mounted antenna has gain in the range of _____________.30. The______________ antenna reduces interference in two different directions

ANSWERS:

1) Poynting vector 2). Omni directional 3). 120'directional 4)11 5) 16-channel combiner 6)six 7)hybrid ring combiner 8)flat 9)location 10) setup-channel11)space diversity . 12)Umbrella 13)discone 14)High gain 15)1.05 16)intermodulation17)ripples 18)fading 19)±2dB 20)Air-pressurized 21)3dB 22)lower 23)Glass mounted24)vertically 25)Horizontally 26)fading 27)True 28)correlation 29)1 to 3 dB 30)parasitic

DESCRIPTIVE QUESITIONS:

1. Concern to the cell site antennas explain startup configuration and abnormal antenna configuration of the startup system.

2. How interference can be reduced by using the directional antennas at the cell site?

3. Assume a receiver is located 10 km from 50w transmitter. The carrier frequency is 6 GHz and free space propagation is assumed Gt=1 and Gr=1w.a)Find the power of the receiverb)The magnitude of the electric field at the receiving antennac)The rms voltage applied to the receiver input assuming that the receiving antenna has purely real importance of 50 ohms and is matched to the receiver.

4. Derive the received power in dBm.How is the measure field strength converted into the received power.

5. Explain in detail about minimum separation of cell site receiving antennas.

6. What are the various cell site antennas that can be used in cellular mobile communications?

7. What are the various mobile antennas that can be used?

UNIT-6

FREQUENCY MANAGEMENT AND CHANNEL ASSIGNMENT


1. Allocation of specific channels to cell sites and mobile units is called2. The ___________ setup channel function as the paging channel for responding to the mobile

originating call3. The mobile unit selects the setup channel of one cell site and makes the mobile originating call is

called as4. Assume that the registration for each MU is 5 times per hour. Each registration takes 100ms.If

20,000MU are on the road, then time spent on setup channels is5. _____________ is a short term traffic relief scheme.

6. Set up channels are also called as________. 7. Assigning voice channels and set up channels is generally done by________. 8. For short term assignment, one channel assignment per call is handled by_______ 9. There are about ___________ setup channels in each block. 10. FOCC is abbreviated as ______ 11. RECC is defined as _______ 12. If the received power level is ____________ than the given setup threshold level, the call request will be taken 13. DCC is meant as ______________ 14. ________ message may be sent with a system parameter overhead message. 15. The____________ of the setup channel can be varied in order to control the number of incoming calls. 16.In cellular systems 80 percent of the calls originate from the_________ but only 20 percent orginate from the ________ 17) Channel borrowing can be implemented from one cell site face to another face at the same cell site T/F 18)___________ scheme is used for slowly growing systems. 19)When the mobile signal is higher than a level L1 ,the call is handed off to_________ cell. 20)When the signal is lower than a level L2 the call is handed off to __________ cell

ANSWERS:1. channel assignment 2) Forward 3) self-location scheme 4) 166.7 min/hr 5) sharing 6)control channels 7) FCC 8)MTSO 9)21 10)forward control channel 11) Reverse control channel 12)greater 13)Digital color code 14)Control-filler message.15) power 16) mobile unit,landline 17)True 18)channel borrowing 19)underlaid 20)overlaid.

DESCRIPTIVE TYPE QUESTIONS

1. Discuss the concept of frequency management concern to the numbering the channels and grouping into the subset.

2. Write the procedure to allot the channels for travelling mobile units.

3. Explain the channel assignment to the cell sites based on the adjacent channels.

4. Write the concept of self allocation scheme at the mobile unit and the autonomous registration.

5. Present the reuse partition scheme in overlaid cell system, mention the advantages associated with it.

6. What do you understand by non-fixed channel assignment? Describe the corresponding algorithm.

UNIT-7 HANDOFFS AND DROPPED CALLS


1. Once a call is established, the _________ channel is not used again during the call period.2. Hand offs is always implemented on_______ channel.3. __________ is needed in two situations where the cell site receives weak signals from the mobile

unit.4. The signal strength threshold level for hand off is ____ in noise limited system.5. The value of C/I at the cell boundary for hand off should be ________ dB in order to have toll

Quality voice.6. The smaller the cell size, the ______ the number and the value of implementing handoffs.7. In setting the threshold,-100dBm+∆, if ∆ is too large it may lead to ______8.Advantage of _________ algorithm is that it makes the handoff occur at the proper location and eliminates possible interference in the system.9._______ is defined as a handoff which would normally occur but is prevented from happening.10The MTSO always handles the ________ call first and the originating calls second.11.________ handoffs are more effective than two-threshold level handoffs.12. A queuing scheme becomes effective only when the requests for handoffs arrive at the MTSO in ____________.13. The _______ can control a hand off by making either a handoff earlier or later.14. If the handoff request arrive at MTSO _______,then the queuing scheme is not needed.15. In_______ system, one time slot is used for serving a call ,rest of the time slot used for monitoring the signal strength.16. When the mobile unit leaves its home cell and enters a new cell, its frequency does not

change. This handoff is called________17. The soft hand off is applied to ________ systems18. In__________ systems all cells can use the same radio carrier19.In power difference hand off if ∆> 3dB, there is a ____________ 20. In power difference hand off if ∆<-3dB, then there is______________ 21.If there is a possibility that a call will drop due to the poor signal of the assigned voice channel,this is considered a _______call . 22. Dropped call rate can be set very low if we do not need to maintain________ 23. The dropped call rate and the specified voice quality level are___________ proportional 24. After cell splitting,new cell radius=_________. 25 The cell splitting for which the installation of every new split cell has to be planned ahead of time is known to be_________. 26 .The algorithm for ________splitting cell sites is a tedious job. 27.The limitation of cell splitting size depends on___________ and _________. 28.__________ type of antennas can be attached to the outer walls of the buildings in different Directions. 29.________ are used for determining the direction and the distance a vehicle has traveled from a predetermined point at any given time. 30.For rapid addition of new cell sites to an existing system,___________ are used to serve the traffic temporarily

ANSWERS:1.set-up 2)voice 3)Handoff 4)-100dBm 5)18dB 6)greater 7)unnecessary hand offs8)two-level hand off 9)Forced hand off 10)handoff 11)Queuing 12)Bundles or batches.14)uniformly 15)TDMA 16)cell site handoff 17)CDMA 18)CDMA 19) request for hand off.20)no handoff 21)dropped 22)voice quality 23)inversely 24) old cellradius/2 25)Permanent cell splitting 26).Dynamically 27)radio aspect ,capacity of the switching processor .28)panel type 29)gyroscope and a fifth wheel 30)portable cellsites

DESCRIPTIVE QUESTIONS

1.Why handoff is necessary for cellular systems? Determine the two types of handoffs based on signal strength and C/I ratio.

2.List and briefly define different performance metrics that may be used to make the handoff decision

3.Explain the difference between soft hand off and hard hand off.

4.Derive the blocking probability for handoff calls and the blocking probability of originating calls

5.Explain intersystem handoff

6.Define the droped call rate.How dropped calls considered?

7.How do you find the values of δ and µ related to the call?

8.Explain the microcell concept in cellular system.

UNIT-8 DIGITAL CELLULAR SYSTEMS


1. In GPS the _ code is used only by military force.2. In GSM, the TDMA structure has __________ time slots per radio carrier.3. Total no of radio carriers in GSM is4. __________ scrambles and spreads a sequence of bits prior to transmission5. . ----------- modulation scheme is used in GSM.6. The MS includes __________ and __________.7. TRAU is abbreviated as____.8._________coordinates call set up to and from GSM users.9.__________ ia a gateway for MSC to interface with external networks for communication with users outside GSM.10._________ is a database which contains subscriber information and information related to to the subscribers current location.11.In order to setup a requested call, the call is initially routed to __________,which finds the correct HLR.12._________ optimizes the cost of the signaling transport among MSC/VLR, GMSC, and HLR.13.____________ generates speech waveform by using a filter with eight transmitted coefficients with a speech frame of 20ms.14.____________ detects the DTX mode.15.__________ is a combination of FDMA AND TDMA.16. Frame interval in GSM is_________17.________ uses the idea of tolerating interference by spread spectrum modulation.18.____________ is a packet switching system which uses idle voice channels from the cellular system band to carry out traffic.19.________ is a cellular –like system developed by Motorola to operate at the special mobile radio band.20. The output of an error –correcting encoder is called ________.21. The mobile station and the base station shall have a delay interval compensation of up to______22.The numbering of the uplink slots is derived from the downlink slots by a delay of _______ in GSM.23. GSM has a slow frequency hop of about ________.24_________ improves transmission quality when interference, multipath fading and Doppler shift are encountered.25. Cancatenation codes use convolution code as inner code and ___ code as outer code.26.__________ codes are used to correct random errors.27. The operating bandwidth for GSM is given by________.28The modulation rate of a GSM carrier is ___________.29. In TDMA structure each frame is ________ long and has _time slots30The NA-TDMA speech coding is a class of speech coding known as ------------------------

ANSWERS:

1. P 2) 8 3) 124 4) Interleaving 5) GMSK 6) subscriber equipment and SIM7) transcoder/rate adaptation unit 8)MSC 9)IWF 10)HLR 11)gateway MSC12)Signaling transfer point. 13)Linear predictive coding 14)voice activity device15)GSM 16)4.615ms 17)CDMA 18)CDPD 19)MIRS(mobile integrated radio service)20)code symbol. 21)one symbol length 22)3 timeslots 23)217 hops/s 24)channel coding25)fire codes 26)convolution 27)935-960MHz uplink,890-915MHzdownlink28)270kbps 29)40ms,6 30)code excited linear predictive coding

DESCRIPTIVE QUESTIONS:

1. Explain GSM services and uses.

2. Explain about traffic channel in GSM.

3.Explain in detail about multiple access scheme.

4.What is the difference between TDMA and GSM architectures.Expolain in detail TDMA.

5.What are the advantages and disadvantages of CDMA in cellular network

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