What is Mobile Station Roaming Number (MSRN)?
The MSRN is used to identify a subscriber when routing the
call from the GMSC to the visited MSC for mobile terminating calls.. It is
allocated by the MSC/VLR currently serving the subscriber on a call basis (temporary
assignment)
What is discontinuous Reception?
For the sake of battery consumption in MS, it is important
to minimize the amount of information the MS has to receive, demodulate and
analyze when it is in idle mode. Therefore the downlink common control channel
is divided into several paging sub channels and all messages pertaining to a
given subscriber are sent on the same sub channel. Such a scheme allows the MS
to restrict the monitoring of paging messages to their own paging sub channel,
thereby increasing the life time of the battery at the expense of a small
increase in the delay for the setting up of incoming calls.What is Discontinuous Transmission?
Discontinuous transmission (DTX) is a method that takes advantage of the fact that a person speaks less that 40 percent of the time in normal conversation by turning the transmitter off during silence periods. Power is conserved at the mobile unit by appling Discontinuous Transmission. Whether DTX should be applied or not is decide by the MSC while its execution is controlled by the BSC.
What is Location Updating?
When a MS moves to a new location area or is switched on in a new location area, it must register with the network to indicate its current location. A location update message is sent to the new MSC/VLR, which records the location area information, and then sends the location information to the subscriber's HLR
What are the various types of bursts in GSM?
Normal Burst
Synchronization Burst
Dummy Burst
Frequency Synchronization Burst.
Draw and Explain the Protocol architecture of the GSM
Network?a. RR Management sub layer
Manages the Radio Interface
Terminates at BSS from MS
b. MM sub Layer
Terminated at MSC
Messages from or to the MSC are relayed transparently from BSS
c. Communications Management sub Layer
Terminates at MSCContains entities that consist of CC including call related supplementary services, SMS and call independent Supplementary Services (SS) support.
d. TCAP and MAP
These are the interfaces between the MSC and HLR/VLR
e. BSSAP
Used to implement all procedures between the MSC and the BSS
that require interpretation and processing of information related to single
calls and resource management.
f. SCCP and MTP
SCCP and MTP protocols are used to implement the data link
layer and layer 3 transport functions for carrying the call control and
mobility management signaling message son the BSS_MSC link.What is the basic procedure for RF planning using RF planning tool in GSM?
Planning Toolloading of digital map data of the city on the planning tool, Model tuning for proper prediction on the tool ,Nominal cell planning for the coverage ,frequency planning and interference study.Final system planning.
What are the different types of antennas used in a GSM network?
Antennas of different types based on antenna beamwidth and gain,
in GSM We have space diversity antenna and cross polorised antenna.Omni antennas,
How do the power, orientation, beamwidth, tilt and height of the antenna affect the coverage?
Power increases the coverage, Proper Orientation, Beamwidth and tilt improves the coverage of the planned area. Increase in antenna height improves the coverage.
What is EIRP? How is it calculated?
Effective isotropic radiated power is the total o/p power of Base station
EIRP=BTS (O/P) power+Antenna gain-cablelosses-other (combiner)losses
What is frequency planning? Why is frequency reuse
pattern used?
Frequency planning is to be done for the GSM network for a
given operator withA set of GSM frequency band.Frequency reuse pattern is used for capacity planning.
To minimize frequency interference problems.
What are all the patterns available? How is frequency planning done on planning tool?
4/12 pattern.3/9 pattern .Automatic frequency planning can be done in planning tool.
What is co-channel interference and adjacent channel interference?
The interference caused by using same channels in a network is called cochannel interference and interference caused by adjacent channels of is called adjacent channel interference.
How do you minimize co-channel interference?
proper frequency planning and proper reuse pattern.
How do you minimize adjacent channel interference?
Proper frequency planning.
What is model tuning? Why is it used? Okarama Hatta model?
Model tuning is done for any planning tool to obtain proper prediction expected from
planning toolas there will be difference in actual and predicted data for planning tool. One of the model is Okarama Hatta.Hatta Model is used which considers the signal propagation losses.
What is link Budget Analysis used for in GSM?
Link budget analysis is used for the path balance between both uplink (Transmitter)
Downlink (Receiver) part of the network.
How is path loss taken into calculation?
This is the total path loss occurred due to multipath propagation of the signal between transmitted signal and the received signal level.
What is capacity planning?
This is process of increasing traffic by adding Trxs traffic channels and proper use of frequency reuse pattern. Addition of BTSs
How is site selection done for planning and site acquisition?
After nominal cell planning with the geographical coordinates identifying best site candidate in a geographical area is the process of site selection.
What is optimization? What are the tools used for optimization?
Once GSM network is integrated in order to achieve proper planning prediction
RF parameters Optimization is done. Drive test tool,Planning tool and Post processing tools are Used for optimization.
How do we use the above antenna patterns for optimization?
Proper antenna orientation and tilts and antenna types can be used for optimizing network.
How do we handle poor C/I, C/A, handover problems and blocking?
Checking proper neighbor list, changing frequency planning and proper no of radio channels availability.
What is system information?
System information is from BTS sent to Mobile for the idle mode and dedicated mode of the call for call management.
What is bench marking in GSM?
Bench Marking used for comparing performance of different network for quality and call performance parameters.
What is Erlang table?
This is the table for calculating Traffic in erlang for no of channels.
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What
is grade of service?
Grade of service is the blocking for the given traffic channels.
How do you optimize a network using OMCR performance data?
Proper increase in call success, and increase in handover success performance and drop call reduction performance.
What is daily report and traffic?
This is the report obtained in OMC for the performce of all BTS about traffic.
What is cell reselect hysteresis?
This is process of handover done by mobile in idle mode from selected cell to another cell.
What is path loss criterion (C1)?
How is it calculated?
This is the signal strength measured in idle mode for selecting best serving channel.
what is authentication, why do we need it and what is its algorithm?
Authentication is the process of uniquely proving an identity to a certain service, network or device and the verification of the given identity.The Au C is associated with the HLR (Home Location Register) in a GSM or UMTS network. It provides authentication parameters for the authentication process such as authentication triplets in GSM or authentication vectors within UMTS
A3 - Authentication Algorithm A3
Authentication algorithm used in conjunction with Ki the authentication key and RAND the random number generated in the AuC (Authentication Centre) to produce the SRES (Signed Response) This variable is used by the network to authenticate a MS (Mobile Station) requesting network resources.
What is equalization?
Equalization is the technique used to improve the redial link performance. That is to minimize instantaneous bit error rate (Inter symbol interference).since the mobile feeding channel is random and time varying, equalizers must track the time varying characteristics of the mobile channel, and thus are called as adaptive equalizers. In reality, bit errors often occur in sequence, as caused by long fading dips affecting several consecutive bits. Channel coding is most effective in detecting and correcting single errors and short error sequences. It is not suitable for handling longer sequences. For this reason, a process called interleaving is used to separate consecutive bits of a message so that these are transmitted in a non-consecutive way.
What is interleaving?
The major drawback of interleaving is the corresponding delay: transmission time from the first burst to the last one in a block is equal to 8 TDMA frame.
What is digitization?
Digitization is the process of converting information into a digital format. In this format, information is organized into discrete units of data (called bits) that can be separately addressed (usually in multiple-bit groups called bytes). What is speech coding? The GSM speech code transform the analog signal (voice) into a digital representation, has to meet the following criteria: A .good speech quality B. to reduce the redundancy in the sounds of the voice
Grade of service is the blocking for the given traffic channels.
How do you optimize a network using OMCR performance data?
Proper increase in call success, and increase in handover success performance and drop call reduction performance.
What is daily report and traffic?
This is the report obtained in OMC for the performce of all BTS about traffic.
What is cell reselect hysteresis?
This is process of handover done by mobile in idle mode from selected cell to another cell.
What is path loss criterion (C1)?
How is it calculated?
This is the signal strength measured in idle mode for selecting best serving channel.
what is authentication, why do we need it and what is its algorithm?
Authentication is the process of uniquely proving an identity to a certain service, network or device and the verification of the given identity.The Au C is associated with the HLR (Home Location Register) in a GSM or UMTS network. It provides authentication parameters for the authentication process such as authentication triplets in GSM or authentication vectors within UMTS
A3 - Authentication Algorithm A3
Authentication algorithm used in conjunction with Ki the authentication key and RAND the random number generated in the AuC (Authentication Centre) to produce the SRES (Signed Response) This variable is used by the network to authenticate a MS (Mobile Station) requesting network resources.
What is equalization?
Equalization is the technique used to improve the redial link performance. That is to minimize instantaneous bit error rate (Inter symbol interference).since the mobile feeding channel is random and time varying, equalizers must track the time varying characteristics of the mobile channel, and thus are called as adaptive equalizers. In reality, bit errors often occur in sequence, as caused by long fading dips affecting several consecutive bits. Channel coding is most effective in detecting and correcting single errors and short error sequences. It is not suitable for handling longer sequences. For this reason, a process called interleaving is used to separate consecutive bits of a message so that these are transmitted in a non-consecutive way.
What is interleaving?
The major drawback of interleaving is the corresponding delay: transmission time from the first burst to the last one in a block is equal to 8 TDMA frame.
What is digitization?
Digitization is the process of converting information into a digital format. In this format, information is organized into discrete units of data (called bits) that can be separately addressed (usually in multiple-bit groups called bytes). What is speech coding? The GSM speech code transform the analog signal (voice) into a digital representation, has to meet the following criteria: A .good speech quality B. to reduce the redundancy in the sounds of the voice
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