CS MOBILE AND PERVASIVE COMPUTING. YEAR & SEM: IV & VII Jochen Burkhardt, Pervasive Computing: Technology and Architecture of Mobile. Internet Applications .. Write notes on wireless sessions protocol. 4. Discuss about. The fourth Year,seventh semester Anna University notes for Mobile And Pervasive Computing (Subject Code: CS) is made available. CSMOBILE AND PERVASIVE COMPUTING 4) Explain the various applications of mobile computing. . Write notes on wireless sessions protocol. 4.

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Such a huge collection of questions with answers! It is very helpful! Thank you so much!!! Jochen Burkhardt, Pervasive Computing: How to improve signal reception by countered the negative effects of multipath propagation? Signal degradations due to multipath are fading and delay spread.

Fading can be overcome by diversity reception. Delay spread will result in Inter Symbol Interference which can be compensated by equalizers.

What are the advantages of cellular systems? The advantages of cellular systems are. List out disadvantages of cellular systems. Unless all of the mobile users are perfectly synchronized, the arriving transmission from notew users will not be perfectly aligned on pervaxive boundaries.

Thus the spreading sequences of the different users are not orthogonal and there is some level of cross correlation. Signals closer to the receiver are received with less attenuation than signals farther away. Given the lack of complete orthogonality, the transmissions from the more remote mobile units perasive be more difficult to recover.

Thus, power control techniques are very important in a CDMA system. A smooth handoff from one cell to the next requires that the mobile unit acquires the new cell ontes it relinquishes the old. What are the three services offered by GSM?


Three services offered by GSM are. What are the tele services of GSM? GSM mainly focuses on voice oriented tele services. The main services are. State the three subsystems of GSM. A Nootes system consists of three subsystems. What are the supplementary services offered by GSM?

Supplementary services offer various enhancements for the standard telephony service. What are the main task of the physical layer in GSM? Channel coding makes extensive use of different forward error correction FEC schemes.

FEC adds redundancy to user data, thus allowing for the detection and correction of selected errors. What are the four possible handover scenarios in GSM? The following are the four possible handover scenarios in GSM. What are the two basic reason mobi,e handover? There are two basic reasons for mobilr. State the security services offered by GSM. The security services offered by GSM are explained in the following.


All user-related data is encrypted. Mpbile are the channel types of GSM system? What is error correction code? A code in which each expression conforms to specific rules of construction so that departures from this construction can be automatically detected and permits the automatic correction of some or all of the errors. What is Error detecting code?

A code in which each expression conforms to specific rules of constructions so that moble certain errors occur in an expression, the resulting expression will not conform to the rules of construction and thus the presence of the errors is detected. FEC stands for forward error correction, it is a procedures whereby a receiver, using only information contained pefvasive the incoming digital transmission, a receiver corrects bit errors in the data. The Network and Switching subsystem consists of the following switches and databases.

What is the function of operation subsystem OSS? The operation subsystem OSScontains all functions necessary for network operation and maintenance. The OSS possess the following entities. What is burst and burst error? Data is transmitted in small portions, called burst. A burst error of kobile B is a mobilf sequence of B bits in which the first and last bits and any number of intermediate bits are received in error.

The guard space is used to avoid overlapping with other bursts due to different path delays and to leave the transmitter time to turn on and off. What is the purpose of comfort noise generated by physical layer of GSM? In voice data transmission, during periods of silence e. What is the use of TMSI?

TMSI is a temporary mobile subscriber identity, it is used to hide the IMSI, which would give away the exact identity of domputing user which is signaling over the air interface.

To locate an MS and to address the MS, the following numbers are needed. What are the security services offered by the GSM?

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The security services cs242 by the GSM are. What are the three algorithms have been specified to provide security services in GSM? The three algorithms have been specified to provide security services in GSM are.

What is challenge-response method? In GSM, authentication uses a challenge-response method: If they are the same, the VLR accepts the subscriber, otherwise the subscriber is rejected.

GPRS stands for general packet radio service, it is a more flexible and powerful data transmission technique. GPRS provides packet mode transfer for applications. While GSM is designed for outdoor use with a cell diameter of up to 70 km, the range of DECT is xomputing to about m from the base station. List the three different categories of services of GSM. Three categories of services of GSM are:. Channel characteristics from one direction to other and vice-versa are same. Refers to any system in which the data speed or quality differ in one direction as compared with other direction.


Bandwidthtransmission power, cost factor are same on both direction.

Differences in transmission power, antenna characteristics. What lowers the data rates available to a user? Data transmission in GSM is possible at many different data rates.

Main reason is the forward error correction to mitigate transmission errors. Furthermore bandwidth is needed for signaling guard spaces. Which elements of the network perform the data transfer? Elements needed for data transfer: What are the reasons for delays in GSM for packet data traffic? State the objectives of UMTS. What are the general problems of satellite signals traveling from a satellite to a receiver?

Terrestrial object that would block the LOS, may result in attenuation of the signal absorption or in distortion due to multipath reflection. pergasive

Atmospheric attenuation is greater at low elevation angle because the signal traverse the atmosphere for longer distances. This is available only in FDD mode.

All inter system handovers are hard handovers. UE receives data from different antennas at the same time makes a handover soft. What are the two basic classes of handover? There are two basic classes in handover: Switching between different antennas or different system is performed at a certain point in time. Which are the new components added to GPRS networks? Users of GSM systems works with telephone numbers. This phone numbers are completely independent of the current location of the user.

The system itself needs some additional information. However, it must not reveal the identity of users.

The international identification of users is done with the IMSI. Notez operation within a location area, only a temporary identifier, the TMSI is needed.


This hides the identity of user. But instead another temporary number reflects the location and any roaming required is the MSRN is used internally by the system. What are the effects of multipath propagation?

The effects of multipath include constructive and destructive interference, and phase shifting of the signal.