Cellular Telephone Concepts - Tomasi Flashcards
ARTS
American Radio Telephone Service
AMPS
Advance Mobile Phone System
USDC
U.S. Digital Cellular
TIA
Telecommunications Industry Assiciation
PCSS
Personal Communications Satellite Systems
Why hexagon shape is chosen as the shape of a cell?
because it provides the most effective transmission by approximating a circular pattern while eliminating gaps inherently present between adjacent circles
Large cells or macrocells have radius between __ and base station transmit power of:
1 mile and 15 miles
1W and 6W
Smallest cells or microcells have radius between __ and base station transmit power of:
1500 ft or less
0.1 W and 1W
Process in w/c the same set of frequencies can be allocated to more than one cell, provided the cells are separated by sufficient distance
Frequency Reuse
Cluster size typically equal to
3,7,12
allows more calls to be handled by the system, provided the cells do not become too small
Cell Splitting
2 major kinds of interference produced within cellular telephone system
co-channel interference
adjacent channel interference
interference between 2 cells using the same set of frequencies
co-channel interference
occurs when transmissions from adjacent channels interfere with each other
adjacent-channel interference
most prevalent when a mobile unit is receiving a weak signal from the base station
near-far effect
when the area of a cell, or independent component coverage areas of a cellular system is further divided thus creating more cell areas
cell splitting
the point when a call reaches maximum capacity occurs when the number of of subscribers wishing to place a call at any given time equals the number of channels in the cell
maximum traffic load
Major drawback of cell splitting:
it results to more base station transfers (handoffs) per call and higher processing load per subscriber
process of subdividing highly congested cells into smaller cells; resizing or redistribution of cell areas
Cell Splitting
decreasing co-channel interference while increasing capacity by using directional antennas is called
Sectoring
placing 2 receive antennas; improves reception by effectively providing a larger target for signals radiated from mobile units
Space Diversity
Controls channel assignment, call processing, call setup and call terminations w/c includes signaling switching, supervision and allocating radio-frequency channels
MTSO / Mobile Telephone Switching Office
Only facility that connect an MTSO
Trunk Circuits
Connection that is momentarily broken during the cell-cell transfer
Hard Handoff
A flawless handoff; No perceivable interruption of service
Soft Handoff
Stages of handoff (4)
- initiation
- resource reservation
- execution
- completion
occurs when a signal level drops below a usable level and there are no usable channels available in the target cell to switch to
Blocking
Roaming from one company’s calling area to another company’s calling area is called __
Interoperator Roaming
MTS
Mobile Telephone Systems
PTT
Push-to-talk
IMTS
Improved Mobile Telephone Systems
The term ____ suggested any radio transmitter, receiver or transceiver that could be moved while in operation
Mobile
The term ____ described a relatively small radio unit that was handheld, battery powered and easily carried by a person moving at walking speed.
Portable
The modern, all-inclusive definition of a ___ ___ is any wireless telephone capable of operating while moving at any speed, battery powered and small enough to be easily carried by a person.
Mobile Telephone
Are fixed-position transceivers with relatively high-power transmitters and sensitive receivers.
Base Stations
Most two-way mobile radio systems can access the PTN only through a special arrangement called ___, and then they are limited to half-duplex operation where neither party can interrupt the other.
Autopatch
The cells that collectively use the complete set of available channel frequencies make up the ___
Cluster
is inversely proportional to the number of cells in a cluster
Frequency Reuse Ratio
cells without gaps in between
tessellate
It occurs if a new call is initiated in an area where all channels are in use
Blocking
It handles all cell-site control and switching functions
Cell-Site Controller
IS-41 relies on a feature called ___
Autonomous Registration
The process where a mobile unit notifies a serving MTSO of its presence and location through a base station controller
Autonomous Registration
Cellular Telephone Network Component (6)
- Electronic Switching Center
- Cell-Site Controller
- Radio Transceivers
- System Interconnects
- Mobile and Portable Telephone Units
- Communication Protocol
Is a digital telephone exchange located in the MTSO that is the heart of a cellular telephone system
Electronic Switching Center
Each cell contains a BSC that operates under the direction of a switching center (MTSO)
Cell-Site Controller
Are also part of the base station subsystem
Radio Transceivers
Four-wire leased lines are generally used to connect switching centers to cell sites and to the PTN
System Interconnects
Governs that way telephone calls are established and disconnected
Communication Protocol
The actual voice channel where mobile users communicate directly with other mobile and wireline subscribers through a base station
User Channel
Used for transferring control and diagnostic information between mobile users and a central cellular telephone switch through a base station
Control Channel
Base station TRANSMITS on __
Forward control channel & Forward voice channel
Base station RECEIVES on __
Reverse control channel & Reverse voice channel
Divide a group of channels into smaller groupings or segments of mutually exclusive frequencies
Segmentation
Is a means of avoiding co-channel interference, although it lowers the capacity of a cell by enabling reuse inside the reuse distance, which is normally prohibited
Segmentation
Is a means of avoiding full-cell splitting where the entire area would otherwise need to be segmented into smaller cells
Dualization
Transmission from base stations to mobile units are called
Forward Links
Transmission from mobile units to base station are called
Reverse Links
Forward links are sometimes called
Downlinks
Reverse links are sometimes called
Uplinks
Mode that allows all calls to pass through the network to the subscriber except for a minimal number of telephone numbers that can be blocked
Available Mode
Mode that is the PCS equivalent to called ID; the name of the calling party appears on the mobile unit’s display
Screen Mode
Mode wherein all calls except those specified by the subscriber are automatically forwarded to a forwarding destination without ringing the subscriber’s handset
Private Mode
Mode wherein no calls are allowed to pass through the subscriber
Unavailable Mode