Cell phone info

20sep05

cell phone table
gsm
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Intro.

This is some cell phone info i've cobbled together from the web. It's mainly US based since that is who we have to contend with here..

Buzzwords:

tdma - time division multiple access.
fdma - frequency division multiple access
cdma - code division multiple access
amps - Advanced mobile phone service
d-amps - Digitial advanced mobile phone service
gsm - global system for mobile communications
gprs - general pack radio service
umts - universalmobile telecomunications service.

Cell phone table

cell phone info
Service	gen	Frequency U-uplink D-downlink	chn spacing	format	who	notes
AMPS (analog) advanced mobile phone service	1g 1983	824-849U 869-894D	30 khz 416 U total 416 D total	fdma each cell used a different freq analog
D-AMPS digital amps IS-54 original IS-136-msging	2g 1990	824-849U 869-894D	30khz	tdma each amps chan split into 3 time slots and digital compression applied	us canada cingular usCellular	end of life, moving to gsm
GSM	2g 1991	850: 824-849U 869-894D 1900 1850-1900U 1930-1990D	200 Khz 14.4kbps	fdma for chan tdma within chan (gaussian min shift keying) (more info)	in pr cingular
cdmaOne IS-95 (qualcom) us	2g		Each carrier 1.25Mhz	spread spectrum
gprs General Packet Radio Service	2.5		200Khz 30/70kbs	Uses unused tdma chan of gsm packet switched Used for text, msging		extension to gsm
cdma20001xrtt	3g		2*1.25Mhz 144kbit/s	spread spectrum extension of cdmaOne	verizon	not compatible with w-cdma
UMTS Universal Mobile telecom	3g 2004	850: 824-849U 869-894D 1900 1850-1900U 1930-1990D	5Mhz Chnspc 1920kbps	w-cdma	cingular to deploy in Us 2005	suceeds gsm

gsm

gsm tutorial ( John Scourias)

gsm format (top)

A combination of TDMA and FDMA
FDMA:

25 Mhz bw split into 124 200 Khz carrier channels
one or more carrier channels are assigned to a base station.

TDMA: each carrier time multplexed

Burst period: 15/26 ms (.577ms) is the basic time unit.
tdma frame= 8 burst periods= 120/26 = 4.615ms. This is the basic unit for a logical channel def.
One physical channel is 1 burst period per tdma frame
Traffic channel (TCH) = mutiframe made up of 26 tdma frames (120 ms)

24 frames for traffic
1 frame for slow associated control channel (sacch)
1 unused
TCH for uplink are separated from TCH for downlink by 3 burst periods.

Control channels (5freq chan).

common channels accessed by idle mode and dedicated mode mobiles.

idl mobiles use common channels to exchange signaling info to move to dedicated mode
dedicated mode mobiles use common channels for base station handoff.

Broadcast control channel (BCCH)

continuos downlink transmission. includes: base station ident, freq allocations, freq hopping sequences.

Frequency correction channel (FCCH) and synchonization chan (SCH)

synchonizes mobiles. Defines boundaries of burst periods and the time slot numbering. Every cell in a gsm network broadcasts exactly 1 FCCH and one SCH which are by definition time slot number 0 of the 8 slot tdma sequence.

Random access chan. (RACH)

slotted aloha channel used by mobile to get access to network.

paging channel (PCH)

alerts mobile to incoming call.

access grant chan (AGCH)

mobile requests on RACH. AGCH then used to allocate a dedicated chan to mobile.