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VARDHAMAN COLLEGE OF ENGINEERING(Shamshabad, Hyderabad)Four Year B.Tech VII Semester CELLULAR AND MOBILE COMMUNICATIONUNIT-I(1 MARK QUESTIONS)Mention the limitations of conventional mobile telephone system.What is the core concept of the cellular communications?Why can the actual shape of the cell may not be either a circle or a regular geometrical shape?Why can the cellular topology not be formed by using ideal circular shape?Distinguish between a cell and a cell-site.List the essential components of a cellular telephone system.What are the different frequency reuse schemes?List the factors to determine the minimum distance between co-channel cells.Mention the categories for specifying performance criteria in a cellular system.From a subscriber’s point of view, list the parts of operation of a cellular system.What are the tasks to be performed by the marketing department in planning a cellular system?List the types of cell splitting.List the major factors for occurrence of handoff.Assume that the allocated number of channels in a cluster are fixed and the size of each cell is kept constant. How will the system design be affected by choosing higher value of cluster size?How will the system design be affected by choosing a smaller value of cluster size?Write the procedure for locating the co-channel cells in the first tier using a regular hexagonal pattern.Which is the main problem caused due to frequency reuse in a cellular architecture?How can it be minimized? Determine the number of cells in a cluster for i=2 and j=4 in a regular hexagonal geometry pattern.Determine the distance from the nearest co-channel cell for a cell having a radius of 0.64 Km and a co-channel reuse factor of 12.Calculate q for a cell radius of 2 km and the distance between two co-channel cells of 9.2 km.Determine the frequency reuse ratio for a cell radius of 0.8 km separated from the nearest co-channel cell by a distance of 6.4 km. Let the radius of the split cells be 50% of the radius of the original cell (before splitting). Show that the coverage area of a split cell is one-fourth the coverage area of the original cell.A mobile communication system has an allocated number of 1000 voice channels. If the service area is divided into 20 cells with a frequency reuse factor of 4, determine the system capacity.A mobile communication system is designed with a cluster size of 7.If the area of the cell is 5 km2, calculate the area of the cluster.A large city with an area of 1001 km2 is required to be covered by a finite number of cells with a radius of 2 km each. How many cell-sites would be required, assuming regular hexagonal-shaped cells?Calculate the number of times the cluster size of 4 have to b e replicated in order to approximately cover the entire service area of 1765 km2 with adequate number of uniform sized cells of 7 km2 each.A cellular system is allocated a total band of 33 MHz and uses two simplex channels to provide full duplex channel. If the simplex channel frequency is 25 KHz then find the number of full duplex channels per cell for a frequency reuse factor of k=7.A cellular communication service area is covered with 12 clusters having 7 cells in each cluster and 16 channels assigned in each cell. Determine the system capacity.Calculate the number of channels per cell for a cluster size of 7 in a cellular system which has 1001 radio channels available for handling traffic. The serving area of the complete system is 2100 km2 and the area of the cell is 6 km2.A new cellular service provider decides to employ a cluster of 19 cells for frequency reuse. Calculate the worst case C/I in dB at the mobile unit, assuming an omni directional antenna system when it is receiving co-channel interference from first tier co-channel cells only. Assume path loss exponent as 4 in a mobile radio environment.UNIT-I(2/3/5 MARK QUESTIONS)What are the limitations of conventional mobile telephone systems? Discuss in detail.Discuss the propagation attenuation and severe fading in a mobile radio transmission medium.Explain the history of 800 MHz spectrum allocation to cellular systems.Describe the performance criteria of a mobile communication systems.Explain the operation of a cellular system in detail.Discuss the amplifier noise in cellular frequency band and derive the expression fornoise figure.Discuss the trunking efficiency degradation and compare one carrier/market and other than one carrier per market with necessary graphs.Discuss in detail the planning of a cellular system.Explain about marketing image of hexagonal cells.What is the concept of frequency reuse and explain how this is useful in increasing the number of channels.Explain the frequency reuse schemes.Discuss about the frequency reuse distance in cellular radio system.Give a general view of cellular telecommunications systems.Explain about the co-channel interference reduction factor and derive the general formula for C/I.From a Normal case, Derive the desired C/I in an omni-directional antenna system.Explain the need of cell splitting. Determine the transmitted power for a new cell after cell splitting.What is meant by cell splitting? How does cell splitting affect the system design? Does the value of frequency reuse factor (q) change due to cell splitting?Distinguish between permanent splitting and dynamic splitting. Consider a single high-power transmitter that can support 40 voice channels over an area of 140 km2 with the available spectrum. If this area is equally divided into seven smaller areas (cells), each supported by lower power transmitters so that each cell supports 30% of the channels, then determine coverage area of each cell and the total number of voice channels available in cellular system.If a total of 33 MHz of bandwidth is allocated to a particular FDD cellular telephone system which uses two 25 KHz simplex channels to provide full duplex voice and control channels, compute the number of channels available per cell if a system uses(i)Four-cell reuse (ii) seven-cell reuse (iii) 12-cell reuse.If 20 MHz of total spectrum is allocated for a duplex wireless cellular system and each simplex channel has 25 kHz RF bandwidth, find: (i) the number of duplex channels.(ii) the total number of channels per cell site, if k = 4 cell reuse is used.Derive a relationship between desired (C/I) and co-channel interference reduction factor (q) in a 7-cell frequency reuse regular hexagonal pattern. Assume all cells are of equal size and use omni directional antennas at the cell-site.Determine the number of channels per cluster and the total channel capacity for a cellular telephone area comprised of 10 clusters with 7 cells in each cluster and 10 channels in each cell.Assume a cellular system of 32 cells with a cell radius of 1.6 km, a total spectrum allocation that supports 336 traffic channels, and a reuse pattern of 7. Calculate the total service area covered with this configuration, the number of channels per cell, and a total system capacity. Assume regular hexagonal cellular topology.A mobile communication system is allocated RF spectrum of 25 MHz and uses RF channel bandwidth of 25 KHz so that a total number of 1000 voice channels can be supported in the system.(i) if the service area is divided into 20 cells with a frequency reuse factor of 4, compute the system capacity. (ii) If the same service area is covered with 100 cells. Compute the system capacity while keeping the frequency reuse factor as 4.Consider that a geographical service area of a cellular system is 4200 km2. A total of 1001 radio channels are available for handling traffic. Suppose the area of a cell is 12 km2.(a) How many times would the cluster size of 7 have to be replicated in order to cover the entire service area? Calculate the number of channels per cell and the system capacity.(b) If the cluster size is decreased from 7 to 4, then does it result into increase in system capacity?Comment on the results obtained.A cellular service provider is allocated an RF spectrum of 30 MHz. The cellular system is configured with a cluster size of 12. It has simplex channel bandwidth of 25 kHz and 10 channels per cell are reserved as control channels. (i)Find the reuse distance if the radius of each cell is 5 kms.(ii) How many channels per cell are available for traffic purpose.(iii) How many calls can be simultaneously processed by each cell if 8 users can share each channel?For an identical received power at the boundaries of original larger cell radius Ro and the new split cell with radius Ro/2, prove that the cell-site transmitter power of the split cell must be 12 dB less than the cell-site transmitter power of the original larger cells. Assume path-loss exponent as 4 in a typical mobile environment.A cellular system covering a geographical area of 1520 km2 supports 1140 radio frequency channel. If frequency reuse concept is implemented in this system such that the first tier co channel of any given cell is located by traversing three cells along a chain of hexagons and two cells after a counter clockwise turning by 60o, determine for a cell area of 4 km2The number of cells in each clusterThe number of cellular cluster in the systemThe area of each cellular clusterThe increase system capacityThe number of radio frequency channels serviced by each cell with and without frequency reuse.DetermineThe channel capacity for a cellular telephone area comprised of seven macro cell with 10 channels per cell.Channel capacity if each macro cell is split into four minicells.Channel capacity if each minicell is further split into four microcells.UNIT II(1 MARK QUESTIONS)How is signal quality affected by employing frequency reuse concept in cellular communication systems?Can the value of cluster size be increased more than 7 to minimize the effect of co-channel interference?What could be the possible sources of interference which may limit the performance of cellular communication systems?List the methods to reduce co-channel interference in cellular communication network.List the types of antenna downtilting schemes used to reduce the interference.Which technique could be deployed to achieve higher value of C/I at the mobile unit in a fully equipped regular hexagonal cellular pattern?What are the conditions under which cellular phone systems and UHF TV systemsinterfere with each other?Mention the types of interference that can occur between UHF television and 800 MHz cellular mobile phones.What are the two causes of concern of near-end-far-end interference?What are the functions of Mobile Telephone Switching Office (MTSO)?List the different ways of combining a driven antenna and a single parasite to reduce the interference.Mention the UHF frequency range. Expand UHF.Calculate the Third-order intermodulation product given that the mobile transmit frequency is 833.25 MHz and TV transmit frequency is 831.25 MHz.Convert +33 dBm into absolute power. Convert - 13 dBW into absolute power.To reduce CCI power control is exercised by which component of a Cellular Mobile Communication system and explainIn a valley, the effective antenna height as seen from the mobile unit is 2/3 of h1 where h1 is the actual antenna height. Calculate antenna gain reduction if the antenna is lowered to half of h1.Mention the tilt angle to reduce the co-channel interference in a seven cell cellular system (k=7).Calculate the change in received signal strengths (dB) in a mobile radio environment when the second distance point is 10 times the distance of the first point.At the base station , the transmitted power of 100 W plus an antenna gain of 9 dBi is assumed at one transmitting antenna. The receiving antenna , located at the same site , also has a gain of 9 dBi and receives a mobile signal of - 100 dBm. Calculate the difference in signal strength.If a separation of 5B ( five channel bandwidths ) is needed for two adjacent channels in a cell in order to avoid near-end-far-end interference , calculate the adjacent channel frequency given that the present channel is 889.98 MHz. Assume B to be 30 KHz.Write down the FRIIS Transmission formula.Calculate the SINAD in dB given that total output power is 100 mW and nonsignal portion ( noise + distortion) is 1mW.The total no. of Full duplex channels in an area are 1140. The total no. of Full duplex channels in a cell are 380. Calculate the frequency Reuse Factor and Cluster Size.If the reverse (mobile to base station) channel frequency is 833.25MHZ, Calculate the forward (Base station to Mobile) channel Frequency.If the forward (Base station to Mobile) channel frequency is 878.25MHZ, Calculate the reverse (mobile to base station) channel Frequency.Determine the transmit and receive carrier frequencies for AMPS (Advanced Mobile phone service) channel 3.During a busy hour, the no. of calls per hour Qi for each of 10cells is 2000,1500,3000,500,1000,1200,1800,2500,2800,900. Assume that 60% of the car phones will be used during this period and that one call is made per car phone. Calculate the no of customers in the system.A cell site transmitter generates a +15dBm RF signal and is connected to an antenna using an RF coaxial cable that induces a 3dB loss. The cable has two connectors at its either end that induce a loss of 2dB each. What is the signal level at the input of the antenna?Why diversity scheme is applied at the receiving end of the antenna?UNIT-II(2/3/5 MARK QUESTIONS) Discuss in detail the various techniques to measure co-channel interferenceExplain the detection of co-channel interference areas from mobile receivers basedon test 1.Derive worst case C/I in an omni-directional antenna system for K=9 frequency reuse pattern.Explain the design of a directional antenna system for 3-sector and 6-sector case of K=4 cell pattern in the worst case.Explain the importance of the antenna height in reduction of co-channel pare the co-channel interference performance of a directional antenna system for k =7 and k=4 cell patterns.How the use of parasitic elements give the reduction in co-channel interference? Explain.Explain about the nonlinear amplification in Non co-channel interference.Explain the effect of umbrella pattern antennas?What are the advantages of using umbrella pattern antenna at cell site?What is tilting of an antenna? How can these antenna patterns reduce the co-channel interference?Explain the effect of lowering the antenna height on a high hill, in a valley and in a forested area.Give the differences between next channel interference and neighboring channel interference.Write the effects on mobile systems by applying the power decrease and antennaheight decrease on coverage and interference.Explain the occurrence of near-end-far-end interference in one cell and two cell system.Explain how to avoid the near-end-far-end interference.Describe the conditions under which cellular phone systems and UHF TV systemsinterfere with each other?Briefly explain the interference of cellular mobile receivers by UHF TV transmitters.Describe the interference to UHF TV receivers from cellular mobile transmitters.Determine the minimum cluster size for a cellular system designed with an acceptable value of carrier-to- interference ratio C/I =18 dB. Assume the path loss exponent as 4 and co-channel interference at the mobile unit from six equidistant cells in the first tier.Determine the carrier-to- interference ratio C/I at the mobile receiver located at the boundary of its omnidirectional operating cell, under the influence of interfering signals from six co-channel interfering cells in the first tier in a cellular system designed with(i) K =7 (ii) K = 9 (iii) K = 12A cellular system is designed with a 3-sector directional antenna configuration. A cluster pattern of size 7 is deployed. Let the mobile receiver be located at the boundary of its operating cell, and be under the influence of interfering signals from two co-channel interfering cells in the first tier. Compute the worst case carrier-to- interference ratio C/I at the mobile receiver. If the C/I value for a practical system requires 6 dB higher than the theoretical value of C/I = 18 dB then comment on the results obtained. Assume the path loss exponent as 4 in a mobile radio environment. Compute the worst case C/I value at the mobile receiver located at the boundary of its serving cell if it is under the influence of interfering signals from two nearest co-channel interfering cells in a cellular system. The system is designed with 3-sector directional antenna system with a reuse pattern of 4. Does this system yield an adequate value of C/I for a practical system which requires 6 dB higher than the theoretical value of C/I = 18 dB?Calculate the carrier-to- interference ratio C/I at the mobile receiver located at the boundary of its operating cell, under the influence of interfering signals from one co-channel interfering cell in the first tier in a cellular system designed with 6-sector directional antenna cellular system designed a reuse for K = 7. Comment on the results for a practical cellular system. Assume the path-loss exponent as 4.Show that the worst case C/I at the mobile receiver located at the boundary of its serving cell, under the influence of interfering signals from one co-channel interfering cell in the first tier in a cellular system designed with 6-sector directional antenna cellular system designed for K = 4 is adequate for a practical cellular system in which there may be 6 dB performance margin needed. Assume the path-loss exponent as 4.A new cellular service provider decides to employ a cluster of 12 cells for frequency reuse. Calculate the worst case C/I (in dB) at the mobile, when it is receiving co-channel interference from first tier co-channel cells only. Assume path loss exponent as 4 in a mobile radio environment.Prove that C/I performance of 3-sector cellular design improves over omni directional design by more than 6 dB. Assume propagation path-loss exponent as 4 and cluster size 7 in a regular hexagonal cellular pattern.Show that K = 7, six-sector configuration has better C/I performance than K = 4, six-sector cellular system. Assume regular hexagonal cellular architecture.A cellular system is designed with 100 cell-sites deployed with a frequency reuse factor of 4, and an overall of 500 full duplex channels. Determine the number of channels per cell, total number of channels available to the service provider, and the minimum required carrier-to-interference ratio (C/I) of the system in dB in a mobile radio environment. Compare co-channel interference from the first tier of six interferers with that from the second tier of twelve interferers for a seven cell reuse cellular pattern. Assume the path-loss exponent as 4 in a mobile radio environment. ................
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