Networking & Cellular
E14 Cell Networks & Coverage — Study Guide
This guide covers Cell Networks & Coverage as part of Networking & Cellular. Start with the vocabulary, then try to answer each question before revealing the answer. Connect these facts to a real network or cellular connection and practice the subject in the arcade when you are ready.
Acronyms first
| Term | Meaning |
|---|---|
| PLMN | Public Land Mobile Network |
| PUK | Personal Unlock Key |
| MCC | Mobile Country Code |
| EDGE | Enhanced Data rates for GSM Evolution |
Key facts
IMSI is stored in the SIM, HLR, and…
VLR
Which is NOT stored on the SIM?
IMEI
Ki is the ____ key and Kc is the ____ key.
Authentication; Ciphering
Which identifier identifies the DEVICE on the network?
IMEI
Which number identifies a mobile phone number internationally?
MSISDN
Which encrypted ID protects the IMSI and is the first encrypted transmission during registration?
TMSI
An individual who can account for multiple mobile connections (SIMs) is the…
MS (Mobile Subscriber)
Which equipment facilitates wireless comms between UE and the network?
BTS (Base Transceiver Station)
The BSS (Base Station Sub-System) is a group of…
BTSs and a BSC
Which element controls multiple base stations and interfaces cell sites with the MSC?
BSC (Base Station Controller)
Which element handles call set-up, release, and routing?
MSC (Mobile Switching Center)
The Abis interface is between…
BSC and BTS
The A interface is between…
BSC and MSC
The E interface is between…
two MSCs
The Um interface is the ____ interface between mobile and base station.
air/radio
RAND is a random number of how many bits?
128
Ki is a ___-bit value unique to each SIM.
128
Which channel is point-to-multipoint, unidirectional DOWNLINK on the Um interface?
BCCH
Which downlink-only control channel corrects frequency?
FCCH
Which channel alerts a mobile of a waiting call or text?
PCH (Paging Channel)
Which channel carries traffic both up and down after connection, as full or half rate speech?
TCH (Traffic Channel)
MCC first digit 3 means…
North America and Caribbean
MCC first digit 2 means…
Europe
MCC first digit 4 means…
Asia and Middle East
MCC first digit 6 means…
Africa
MCC first digit 7 means…
South and Central America
MCC first digit 9 means…
Worldwide (satellite, ships)
Which MCC first digits are NOT used?
1 and 8
MCC 310 is…
USA
MCC 208 is…
France
MCC 404 is…
India
MCC 505 is…
Australia
MCC 602 is…
Egypt
An MNC of 001 is the same as an MNC of 01.
False
Which validates any SIM attempting network connection?
AuC (Authentication Center)
GSM operates in which bands?
900 MHz or 1.8 GHz
EDGE is considered…
pre-3G (part of ITU's 3G definition)
OSS functions include security management, network configuration, and…
maintenance tasks
Which database stores information from ALL mobile subscribers?
HLR
Which server supports roaming for users outside their HLR's coverage?
VLR
Which register records allowed mobile stations and banned equipment?
EIR (Equipment Identity Register)
ARFCN specifies…
a pair of physical radio carriers (one uplink, one downlink)
In 3G and beyond, the Mobile Station is called…
UE (User Equipment)
Which GSM MS component handles RF transmission handover and speech coding?
Mobile Termination
IMEI is composed of ___ digits plus a check digit (16 for IMEISV).
14
What percent of IMEIs are NOT unique?
10%
Dial what to display the IMEI on most phones?
*#06#
The MSC checks the IMEI with which register to validate a call?
EIR
Uplink is the path from…
mobile station to base station
Cellular is full duplex because it uses…
one frequency for talking and a separate one for listening
A typical cell phone can communicate on how many channels or more?
1,664
Basic components of any cellular system?
Mobile subscriber unit, base station, MSC
Which access topology connects BTSs directly to the MSC site?
Direct Star
Which access topology parents BTSs to a remote BSC/multiplexer before the MSC?
Remote Star
Which access topology chains several BTSs back to the MSC?
Link Multi-drop
Which access topology is like multi-drop but the tail end has a return path to the MSC?
Resilient Ring
Adding BTSs to make smaller cells with lower power and antenna height is…
Cell splitting
Cell splitting can be applied until cell radii reach…
500 meters
Below 500 m radius, what cells are required (antennas below roof level)?
Microcells
Omni-cells typically have as few as three antennas — how are they used?
One transmit, two receive (space diversity)
Which cell type uses directional antennas to divide a region into sectors with higher gain?
Sectored cell
Directional antenna gain increases by increasing the effective…
aperture
How many frequencies per cell are typical with frequency reuse?
10 to 50
Which tower type carries the most traffic in large metro areas (tri-panel)?
Microcell
Which tower type (umbrella cell) serves rural areas and travel routes (bi-panel)?
Macrocell
Which cell serves high-volume enclosed areas like airports and malls?
Picocell
A temporary cell for concerts and sporting events is a…
Cell-on-Wheels (COW)
In digital systems, converting samples into binary is called being…
Quantized
Which is the central coordinator of a cellular system and link to the PSTN central office?
MSC
Which MSC database stores TEMPORARY subscriber info?
VLR
Which MSC database stores and sends encryption data to authenticate the user?
AuC
Which is NOT an MSC operation?
Assigning IMEI numbers
The VLR is always integrated with the MSC.
True
The EIR is typically found only on which networks?
GSM (not CDMA)
EIR color code: authorized?
White
EIR color code: authorized but may need further scrutiny?
Gray
EIR color code: NOT authorized?
Black
The OMC is implemented by the…
OSS (Operation and Support System)
The AuC encryption algorithm is known as…
A3
The digital network divides into which two main areas?
Base station sub-system and network sub-system
A parasitic linear array of parallel dipoles used as a signal booster's external antenna is a…
Yagi antenna
Which antenna is a dipole ahead of a flat-panel reflector, used at base stations?
Panel antenna
Large panel arrays use an edge taper to reduce…
side lobes
How many transceivers can a BTS hold depending on users?
1 to 16
Which device mediates between base stations and MSCs and manages BTS handover?
BSC
Which tool surveys and logs 4G/LTE and 3G/UMTS networks?
SIRETta SENTRY-G-LTE4
Which agency defeated a rogue 3G system threatening American lawmakers?
Secret Service
Which is NOT part of the NSS?
BTS
IWF in the NSS stands for…
Interworking Functions
Transferring an in-progress call from the losing to the gaining base station is…
Handoff
Which handoff switches frequency with a slight cutoff — used in FDMA/TDMA?
Hard handoff
Which handoff overlaps coverage so the phone talks to multiple base stations — used by CDMA?
Soft handoff
When placing a call, the phone broadcasts dialed digits plus which identifiers over the strongest control channel?
MIN and ESN
Which element validates MIN & ESN and sets up the call?
MSC
Order the call setup sequence.
Phone broadcasts digits + MIN/ESN → Cell site passes info to MSC → MSC validates MIN & ESN → MSC selects voice channel and reserves trunks → Phone tunes to assigned channel
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