data rates :

GSM 9.6 kbps

HSCSDR high speed circuit switch data rate 38.4 kbps
assign 4 timeslots for each user ( 9.6 * 4 )

GPRS reach 115.2 kbps
after using 8PSK modulation (38.4 * 3 )

EDGE reach a bout 384 kbps
by defining new modulation scheme and soft ware upgrade for cabinet also using high order 8 PSK modulation

UMTS a bout 2 mbps
install new cabinet ( 3G cabinet ) and use high capacity channel 5 MHZ

LTE can reach 100 mbps downloading and a bout 50 mbps uploading
and more ( practically may be 1 - 10 GBPS )
by using MIMO , OFDMA , 16 and 64 QAM modulation , ....

mobile frame contain 8 time slots

E1 frame contain 32 time slot

T1 frame contain 24 time slot

number of bits per time slot ( burst ) 156 bit

burst duration a bout 577 micro sec

E1 rate = 32 TS * 4000 HZ * 2 ( for sampling condition ) * 8 ( encoding bits ) = 2.048 mbps

T1 rate = 24 * 4000 * 2 * 8 = 1.55 mbps ( by the smae way )

E2 = E1 * 4
E3 = E2 * 4
E4 = E3 * 4

T2 = T1 * 4
T3 = T2 * 7
T4 = T3 * 6

STM 1 rate #sychronous_transport_module
9 row * 270 columns * 4000 HZ * 2 * 8 bits = 155.52 mbps
compare between E4 rate and STM1 rate ( twisted pair , fiber optic transmission )

STM 4 , STM 16 , STM 64 will be discussed later

IEEE standards :

ieee 802 . 15 . 1 #blutooth
ieee 802 . 11 a,b,g,n #wifi
ieee 802 . 16 #wimax
ieee 802 . 14 #cable modems
ieee802 . 24 #smart GRID tag
ieee 802 . 15 . 4 #zig bee
ieee 802 . 8 #fiber optic tag
ieee 802 . 3 #ethernet

blutooth , NFC and wifi spectrum 2.4 - 5 GHZ
ISM band

wimax 2 - 11 GHZ
10 - 66 GHZ
infrared rate 1 - 2 mbps
range 10 - 20 meter ( depending on frequency )

cpd

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<a href="/jobs/view/957/bts-installation-commissioning-and-testing-engineers">BTS Installation, Commissioning and Testing Engineers</a><br>premium<br/>

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Ericsson RBS 3000 series

3106 , 3206 , 3412 , 3418

RBS 3106

3G outdoor cabinet

contain the following units :

1- ACCU

ac connection unit >> used to connect , disconnect and distribute the incoming AC power supply to the PSUs

2- PSUs

power supply unit >> used to converting and rectifying the AC power into -48 volt DC to feed the various units of the RBS

3- DC / DC

dc to dc converter used to convert the incoming -48 volt in to 24 volt it is optional unit

4- power bar

used to distribute the internal -48 volt to the various units from the PSUs to the PDUs AND BFUs

5- PDU

power distribution unit >> used to supply the climate unit , fan control unit and radio units and supply the digital sub rack VIA the CBU

6- BFU

battery fuse unit >> used to connect , disconnect and control the batteries link to the RBS units

7- CU

climate unit >> used to adjust the temperature , humidity of the RBS by the FCU , its located beside the RBS door and contain air to air ex-changer , heating and cooling unit

8- FCU

fan control unit >> its the fan speed controlling unit according to the temp of the RBS various units

9- AUH

auxiliary unit hub >> located in the power subrack , used to connect the auxiliary units like PSUs to the EC

10 - XALM >> external alarm unit

11- DF

distribution frame >> used to provide OVP over voltage protection

DIGITAL SUB RACK

its the main and most important unit in the cabinet

consist of the following units :

a- CBU

control base unit >> its the microprocessor , provide ATM switch for all units connected to the back plane , also provide timing unit and signal clock synchronization , supply the digital sub rack by -48 VDC , finally its provide E1 and T1 interface

b- RAX board

random access and receiver board >> implement he uplink base band processing for signals

c- TAX board

transmission board >> implement the down link base band signal processing

d- RUIF

radio interface unit >> used to connect the radio units and its connected to the ATM switch VIA the digital sub rack

RADIO sub rack

1- provide analog to digital conversion and vice versa
2- signal modulation and demodulation
3- signal RF carrier combining

RU

radio units >> contain the TRX , PA power amplifiers

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radio transmission problems

1- path loss

Reason: ...... increasing distance between MS and BTS

Solution: ...... cut over ( switch it to the nearest cell )

2- shadowing ( normal fading )

Reason: ..... obstacles between MS and BTS

Solution: ..... increasing the receiving margin at the transceiver station

3- multipath fading

Reason: ...... different paths of signals between MS and BTS which

may cause receive the signal in multi phases and amplitudes

Solution: ...... DIVERSITY ( space , frequency , polarization )

4- time dispersion ( ISI inter-symbol interference )

Reason: ...... time dispersion is another problem relating to multiple paths to the RX antenna of either MS or BTS.Time dispersion causes inter symbol interference where consecutive symbols (bits)interfere with each other making it difficult for the receiver, which bits is correct one

Solution: ...... adaptive equalizer by using training sequence in bursts

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