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Right option is (b) Cross TALK

Explanation: Interference on voice CHANNELS causes CRASS talk. Here, the subscriber hears interference in the BACKGROUND due to an UNDESIRED transmission.

Correct answer is (a) PEDESTRIAN users

The BEST explanation: Cell dragging is a practical HANDOFF PROBLEM in microcell system. It results from pedestrian users that provide a very strong signal to the base station.

Correct choice is (a) True

For explanation: Dynamic channel assignment reduces the likelihood of BLOCKING. Accordingly, the MSC only allocates a given frequency if that frequency is not presently in use in the cell or any other cell which falls within the MINIMUM restricted distance of frequency REUSE.

The correct choice is (d) 1/N

The explanation: The FREQUENCY REUSE factor is defined as 1 over the number of cells in the cluster of the SYSTEM (N). It is given by 1/N since each cell within a cluster is only ASSIGNED 1/N of the total AVAILABLE channels in the system.

Right option is (d) Increasing number of base stations

Easiest explanation: The advantage of the zone cell TECHNIQUE is that co-channel interference in the cellular system is reduced since a large CENTRAL base station is REPLACED by several low powered transmitters on the edges of the cell. Thus, signal quality is reduced and it LEADS to an increase in capacity.

The correct option is (b) Mobile assisted handoff

Easy explanation: MAHO stands for mobile assisted handoff. In 2G SYSTEMS, handoff decisions are mobile assisted. In MAHO, every mobile station measure the RECEIVED power from surrounding base station and continuously reports the results to SERVING base station.

Correct ANSWER is (a) RADIUS of CELL

To explain I would say: This is the case when the size of each cell is approximately the same and the base stations transmit the same power. Co-channel interference ratio is independent of the transmitted power and becomes a function of the radius of the cell ® and the DISTANCE between centers of the nearest co channel cell (D).

Correct option is (d) Set up TIME

The EXPLANATION: When any user makes a call request, the time required to allocate a trunked CHANNEL to a user is KNOWN as set up time. TETREA (Terrestrial Trunked Radio) call set up time is 0.3 seconds. GSM uses a call set up time of several seconds.

Correct answer is (a) Process of selecting and allocating channels

For explanation I would say: Frequency REUSE is the process of using the same RADIO FREQUENCIES on radio transmitter sites within a geographic AREA. They are separated by sufficient DISTANCE to cause minimal interference with each other.

Correct answer is (d) Micro CELL ZONE concept

For explanation: Micro cell zone concept distributes the coverage of the cell and extends the cell BOUNDARY to hard-to reach places. It is the solution for the problem of increased number of handoffs when SECTORING which RESULTS in an increase of load on switching.

Correct ANSWER is (b) Q=D/R

To explain: Co-channel REUSE ratio is defined by Q=D/R. By INCREASING the ratio of D/R, the spatial separation between co-channel cells relative to the COVERAGE distance of a CELL is increased. Thus, interference I reduced from improved isolation of RF energy from the co-channel cells.

The correct choice is (a) 1 second

For EXPLANATION: In DIGITAL cellular systems, the mobile assista with the handoff procedure by determining the best CANDIDATE. Once the DECISION is made, it typically requires 1 to 2 seconds for handoff.

The correct choice is (a) Voice channels

To explain: In a FOXED channel strategy, each cell is ALLOCATED a PREDETERMINED set of voice channels. Any call ATTEMPT within the cell can only be served by the unused channels in that PARTICULAR cell.

Right choice is (a) Cell SPLITTING

For explanation: Cell splitting is the process of SUBDIVIDING a congested cell into smaller cells. Each small cell has its own base station and a there is a CORRESPONDING reduction in ANTENNA height and transmitter power.

Right choice is (c) 2%

Explanation: The AMPS (Advanced Mobile Phone System) cellular system is designed for a GOS of 2% BLOCKING. This IMPLIES that the channel allocations for CELL sites are designed so that 2 out of 100 calls will be blocked DUE to channel occupancy during the busiest hour.

The correct option is (b) DYNAMIC and TIME varying COVERAGE region

Explanation: Breathing cell is a concept used by CDMA SYSTEMS. They had a dynamic, time varying coverage region which varies DEPENDING on the instantaneous number of users on the CDMA radio channel.

Right option is (b) Grade of SERVICE (GOS)

The best I can explain: The grade of service (GOS) is a measure of the ability of a user to access a trunked system during the busiest hour. The busy hour is BASED upon CUSTOMER DEMAND at the busiest hour during a week, month or a year.

Right CHOICE is (a) \(\sqrt{(3N)}\)

The best explanation: Co-channel REUSE is defined USING \(\sqrt{(3N)}\). A small value of Q provides larger CAPACITY since the cluster size N is small. However, a large value of Q improves the TRANSMISSION quality, due to smaller level of co-channel interference.

Right option is (B) False

To elaborate: In a DYNAMIC channel strategy, VOICE channels are not allocated to different cells permanently. Instead, serving base STATION requests a channel from MSC each TIME a cell request is made.

The correct answer is (d) HEXAGON

The best explanation: Hexagonal cell SHAPE is a SIMPLISTIC model of radio coverage for each base station. It has been universally adopted SINCE the hexagon permits easy and MANAGEABLE analysis of a cellular system.

The correct option is (c) Cell splitting

The BEST I can explain: Cell splitting allows an orderly growth of cellular SYSTEM. By defining new cells which have a smaller radius than the original cells, CAPACITY increases DUE to additional number of channels per unit area.

The correct ANSWER is (a) Sectoring

The explanation: Sectoring USES DIRECTIONAL antenna to further control the interference and frequency reuse of channels. By DECREASING the cell radius R and keeping the co-channel reuse ratio D/R unchanged, cell splitting increases the number of channels PER unit area.

Correct choice is (b) False

Best explanation: The choice of channel ASSIGNMENT strategy impacts the performance of the system. Particularly as to how calls are MANAGED, when a mobile user is handed off from ONE CELL to another.

The correct option is (a) True

Best explanation: Dynamic channel assignment (DCA) is ONE well known solution to the micro CELLULAR channel assignment problem. The dynamic nature of the strategy permits ADAPTATION to SPATIAL and traffic variations while the distribution of control reduces the required COMPUTATIONAL load.

Correct option is (c) Sectoring

Easy EXPLANATION: Sectored cells EXPERIENCE trunking inefficiencies. Cell splitting and zone micro cell techniques do not suffer the trunking inefficiencies experienced by sectored cells. They ENABLE the base STATION to oversee all handoff CHORES related to microcells, thus reducing the computational load at MSC.

The correct CHOICE is (b) Careful filtering and channel assignments

Explanation: Adjacent channel assignment can be minimized through careful filtering and channel assignments. Each cell is GIVEN only a fraction of the available CHANNELS, a cell need not be ASSIGNED channels which are all adjacent in frequency.

The correct answer is (c) Near-far effect

Explanation: One of the MAIN problems with adjacent CHANNEL interference is the near-far effect. It occurs when a MOBILE close to a base station TRANSMITS on a channel close to one being used by a weak mobile.

The correct CHOICE is (a) Receiver of the subscriber

The best explanation: Near-far EFFECT occurs if an adjacent channel user is transmitting in very close range to a subscriber’s receiver while the receiver attempts to RECEIVE a base station on the desired channel. In this effect, a NEARBY transmitter CAPTURES the receiver of the subscriber.

Right choice is (a) Queuing

To elaborate: Queuing of handoff requests is a METHOD to decrease the probability of forced termination of a call due to LACK of available CHANNELS. Queuing of handoff is possible due to the fact that there is a FINITE time interval between the time the received signal level drops below the handoff threshold and the time the call is terminated.

The correct option is (d) Mobile station

Easiest EXPLANATION: Dwell time of a particular user is governed by a NUMBER of factors. They include PROPAGATION, INTERFERENCE, distance between the subscriber and the base station, and other time VARYING effects.

The correct option is (a) True

The explanation is: Sectoring increases SIR so that cluster size may be REDUCED. SIR is improved USING directional ANTENNA. And then CAPACITY IMPROVEMENT is achieved by reducing the number of cells in a cluster, thus increasing the frequency reuse.

Right answer is (b) False

To elaborate: Handoff OPERATION involves identifying a NEW base station. It also requires that the voice and control signal be allocated to CHANNELS associated with the new base station.

Correct choice is (a) Borrowing channels from neighbouring cell

The explanation is: In borrowing strategy, a cell is allowed to borrow channels from a neighbouring cell if all of its own channels are already OCCUPIED. The MSC supervises such borrowing PROCEDURE and ENSURES that the borrowing of CHANNEL does not INTERFERE with any call in progress.

Correct OPTION is (a) S=k*N

Best EXPLANATION: If there is a cellular system with total of S duplex channels. Each cell is allocated a group of k channels and there are total N CELLS in the system, S channels are divide among N cells into unique and disjoint channel groups. Therefore, total number of RADIO channel is the product of total number of cells in the system (N) and number of channel allocated to each cell (k).

Correct CHOICE is (d) Repeater noise and interference

Best explanation: Upon receiving signals from a base STATION forward link, the repeater AMPLIFIES and reradiates the base station signals to the specific COVERAGE region. Unfortunately, the received noise and interference is also reradiated by repeater on both the forward and REVERSE link.

Correct option is (b) Scattering

The explanation: As the demand for wireless service increases, the number of channels assigned to a call eventually becomes INSUFFICIENT to support the required number of user. Techniques such as CELL splitting, sectoring and COVERAGE zone approaches are USED in practice to expand the capacity of CELLULAR system.

Correct option is (d) Imperfect receiver filters

For EXPLANATION: Interference resulting from signals which are adjacent in frequency to the desired signal is CALLED adjacent channel interference. It RESULTS from imperfect receiver filters which allow nearby FREQUENCIES to leak into the passband.

Right answer is (c) Mobile MOVES from one cellular system to ANOTHER cellular system

Easiest explanation: An intersystem HANDOFF is initiated when a mobile moves from one cellular system to another during a course of a call. An MSC engages in an intersystem interference when a mobile becomes weak in a given cell and MSC cannot find another cell to which call can be transferred.

The correct answer is (c) DWELL time

For explanation: The time over which a call is maintained within a cell WITHOUT HANDOFF is CALLED as dwell time. Dwell time vary depending on speed of USER and type of radio coverage.

The correct answer is (a) A mobile MOVES into a DIFFERENT cell while in conversation

The explanation: Handoff occurs when a mobile moves into a different cell while a conversation is in PROGRESS. The MSC automatically transfers the CALL to a new channel BELONGING to the new base station.

The correct answer is (d) Omnidirectional antenna

To EXPLAIN: For center EXCITED cells, BASE STATION TRANSMITTERS are used at the center of cell. To cover the whole cell, omnidirectional antenna is the best choice for base station transmitters.

Correct answer is (c) Call is blocked

Easy explanation: GOS is TYPICALLY given as the likelihood that a call is blocked or the likelihood of a call experiencing a delay greater than a certain queuing time. It is the wireless DESIGNER’s job to estimate the MAXIMUM required capacity used to allocate the PROPER number of channels in order to MEET GOS.

Right OPTION is (b) Trunking

The best I can explain: Cellular radio systems rely on trunking to accommodate a large number of users in a limited radio spectrum. The concept of trunking ALLOWS a large number of users to share the relatively SMALL number of channels in a cell by providing access to each USER, on demand.