C e l l u l a r T e l e p h o n y I I
by
B r i a n O b l i v i o n
A -=Restricted -=Data -=Transmission
In the last issue we discussed the history of cellular
telephony, monitoring techniques, and a brief description of
its predecessors. In this issue I'll describe the call
processing sequences for land- originated and mobile-originated
calls, as well as the signaling formats for these processes. I
apologize for the bulk of information but I feel it is
important for anyone who is interested in how the network
communicates. Please realize that there was very little I
could add to such a cut and dried topic, and that most is taken
verbatim from Industry standards, with comments and addendums salt
and peppered throughout.
Call-Processing Sequences
Call-Processing Swquence for Land-Originated Calls
MTSO Cell Site Mobile Unit
------------------------------------------------------------------------
------ 1--Transmits setup channel
data on paging channel
2 ----------------------------Scans and locks on
paging channel Receives incoming
call --- 3 and performs translations
Sends paging message ----- 4
to cell site
5 -- Reformats paging
message
6 -- Sends paging message
to mobile unit via
paging channel
7 ----------------------------Detects Page
8 ----------------------------Scans and
locks on
access channel 9
----------------------------Seizes setup channel
10 ----------------------------Aquires sync
11 ----------------------------Sends service request
12 -- Reformats service request
13 -- Performs dirctional locate 14 -- Sends
service request to MTSO
Selects voice channel --- 15
Sends tx-on command to -- 16
cell site
17 -- Reformats channel designation
message
18 -- Sends channel designation
message to mobile unit via
access channel
19 -----------------------------Tunes to
voice channel
20 -----------------------------Transponds
SAT 21 -- Detects SAT
22 -- Puts on-hook on trunk
Detects off-hook -------- 23
Sends alert order ------- 24
25 -- Reformats alert order
26 -- Sends alert order to
mobile unit via blank-
and-burst on voice channel
27 -----------------------------Alerts User
28 -----------------------------Sends 10-kHz
tone 29 -- Detects 10-kHz tone
30 -- Puts on-hook on trunk
Detects on-hook --------- 31
Provides audible ring --- 32
33 -- Detects absence of 10-kHz
tone
34 -- Puts off-hook on trunk
Detects off-hook -------- 35
Removes audible ring ---- 36
and completes connection
Time
Call-Processing Sequence for Mobile-Originated Calls
MTSO Cell Site Mobile Unit
------------------------------------------------------------------------
------ 1 -- Transmits setup channel
data on paging channel
2 --------------------------- Scans and locks-on
paging channel
3 --------------------------- User initiates call
4 --------------------------- Scans and locks-on
access channel
5 --------------------------- Seizes setup
channel 6 ---------------------------
Aquires sync 7 ---------------------------
Sends service request 8 -- Reformats
service request 9 -- Performs directional
Locate 10 -- Sends service request to
MTSO Selects voice channel ---- 11
Sends tx-on command to --- 12
cell site
13 -- Reformats channel
designation message
14 -- Sends channel designation
message to mobile unit via
access channel
15 --------------------------- Tunes to voice
channel
16 --------------------------- Transponds SAT
17 -- Detects SAT
18 -- Puts off-hook on trunk
Detects off-hook --------- 19
Completes call through --- 20
network
Time
Let me review the frequency allocation for Wireline and
non-Wireline systems. Remember that the Wireline service is
usually provided by the area's Telephone Company, in my area
that company is NYNEX. The non-Wireline companies are usually
operated by other carriers foreign to the area, in my area we
are serviced by Cellular One (which is owned by Southwestern
Bell). Each company has its one slice of the electro- magnetic
spectrum. The coverage is not continuous, remember that there
are also 800 MHz trunked business systems that also operate in this
bandwidth. Voice channels are 30 KHz apart and the Data channels
are 10 KHz apart.
Frequency Range Use
----------------------------------------------------------------------
870.000 - 879.360 Cellular One (mobile input 825.000 -
834.360) 880.650 - 890.000 NYNEX (mobile input 835.650 -
845.500) 890.000 - 891.500 Cellular One (mobile input
845.000 - 846.500) 891.500 - 894.000 NYNEX (mobile input
--- GOMail v2.0 [DEMO] 04-03-38
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* Origin: Birdman BBS,Brandon,MB (204)727-3758 (1:348/303) (1:348/303)
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