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وصل الجوال > UMTS > Flashcards

UMTS Flashcards

1
Q

What does HSDPA and what does it stand for?

A

It is a protocol of HSPA group which is protocols group for 3G enhance. It stands for high speed downlink packet access.

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2
Q

What is UMTS and what does it stand for?

A

It is 3G, based on GSM, specification and implementation. It stands for universal mobile telecommunications system.

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3
Q

List requirements of 3G?

A
  • Its major interfaces specifications is open to be universal.
  • It supports multimedia.
  • It services independently of radio access technology and network infrastructure.
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4
Q

What was purpose of 0G, technology of 1G, 2G, 3G and 4G networks? What was addition of 3G over 2G networks?

A

Study mobile radio telephones. Analog. Digital. Digital. IP-based. 3G offered media transfer .

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5
Q

What does EDGE, GPRS, HSUPA and EUL stand for?

A

Enhanced data rates for GSM evolution, general packet radio service, high speed uplink packet access and enhanced uplink

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6
Q

To which of generation and what multiple access technology does these standards use 1G group, IS-136, IS-95, GSM, EDGE, CDMA200, 1XEV-DO, UMTS and LTE. Which generation does GPRS, WCDMA, HSDPA and HSUPA belong?

A

1G uses FDMA. IS-136, IS-95 and GSM are 2G networks. IS-136 and GSM use TDMA while IS-95 uses CDMA. EDGE is a 2.75G network. It uses TDMA. CDMA2000, 1XEV-DO and UMTS are 3G networks. UMTS and CDMA2000 use CDMA and 1XEV-DO use TDMA and CDMA. LTE is 3.9G netowrk. It uses OFDM. 2.5G, 3G and 3.5G and 3.5G.

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7
Q

What does FDD stand for?

A

Frequency division duplexing.

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8
Q

What are names of physical layer at UMTS?

A

WCDMA-UMTS. Also known as Universal Terrestrial Radio Access (UTRA) and UTRA-FDD.

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9
Q

Define DS-CDMA, FDD and TDD?

A

CDMA with DSSS which is modulation with spectrum spread. Operation with two frequencies for receive and send. TDM for sender and reciever.

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10
Q

What is chip and what is its rate unit? What is spreading factor and what is its other name? What is chip rate in UMTS?

A

Pulse in DSSS, MCPS. Chip rate over symbol rate, processing gain. 3.84 Mcps.

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11
Q

What is pilot symbols? What is common pilot channel acronym, its definition? For what purpose are they used in UMTS?

A

Pilot symbols are symbols in message used to demodulate coherently message signals. CPICH, Downlink channel broadcast by BS in UMTS with constant power and of a known bit sequence. Detection.

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12
Q

What is smart antenna? are they supported in UMTS?

A

Antenna array with spatial signal processing algorithms. Supported by specification but implementation is optional.

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13
Q

What is multiuser detection? are they supported in UMTS?

A

Demodulation of mutually interfering signals.. Supported by specification but implementation is optional.

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14
Q

For UMTS physical layer, what is its multiple access technique? its duplexing methods? channels number and width? frame length?

A

DS-CDMA. FDD/TDD. Pair of 5 MHz wide channels. 10 ms.

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15
Q

What is service multiplexing? Does UMTS support it?

A

Different QoS requirements supported on one

connection. Yes.

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16
Q

What is multirate, with explaination? does UMTS support it?

A

Variable spreading factor and
multicode. Multicode is a user that requires more bandwidth would be allocated
more codes. Spreading factor is chip rate over symbol rate. Yes.

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17
Q

What are decendents of CDMA?

A

CDMAOne, CDMA2000 and W-CDMA.

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18
Q

What are decendents of CDMAOne?

A

IS-95A and IS-95B.

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19
Q

What are decendents of CDMA2000?

A

CDMA2000 1XEV and CDMA2000 3XRTT.

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20
Q

What are decendents of CDMA2000 1XEV?

A

CDMA2000 1XEV-DO and CDMA2000 1XEV-DV.

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21
Q

What is other name for CDMAOne?

A

IS-95.

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22
Q

What is other name of CDMA2000?

A

IMT-2000 CDMA MC.

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23
Q

What is difference between CDMA2000 1xEV-DO and CDMA2000 1xEV-DV?

A

CDMA2000 1xEV-DO supports data only while CDMA2000 1xEV-DV supports data and voice.

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24
Q

What is rate of data and carrier width in CDMA2000 1xEV? To which generation does it belong?
144 Kbps on 1.25 MHz as CDMAOne rate.

A
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25
Q

What is added features of CDMA2000 3XRTT? Its rate and channel width?

A

It added multi-carrier support, circute and packet switching, wider channel of 3*1.25 = 3.75 MHz. 2 Mbps.

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26
Q

What is diversity schema? Why it is used?

A

Use of two different channels for one communication. Multipath fade combat.

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27
Q

What are added features of W-CDMA?

A
  • Higher capacity.
  • Diversity schama use.
  • Variable rate.
  • Soft handoff.
  • Support different QoS requirements.
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28
Q

What are examples of applications with different QoS?

A
  • Real-time like voice and video telephony.
  • Streaming like video watching and audio listening.
  • Interactive like web browsing.
  • Background like email service and download.
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29
Q

What controls rate variablility? What is its main benefit?

A

Voice activity. Mobile battery life extend.

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30
Q

What is coherence bandwidth?

A

Bandwidth of maximum for channel that any two signals have same amount of fade.

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31
Q

What is narrowband? wideband?

A

Narrowband is channel that allows messages below its coherence bandwidth. Wideband is channel with messages larger than its coherence bandwidth.

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32
Q

What is rake receiver?

A

It is device for signal opposing multipath fading effect. It decodes and combine different paths of signal.

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33
Q

What does UTRAN stands for? What is its defenition? What do UE and CN stand for?

A

UMTS terrestrial radio access network. Network system for connecting mobiles with Internet and telephone. User equipment and core network

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34
Q

What does DSSS stand for? What is its definition?

A

Direct-sequence spread spectrum. Modulation with spectrum spread. Signal is spread over wideband at sender and despread to narrowband at reciever.

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35
Q

What is multipath diversity?

A

Paths for several signals reaching antenna.

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36
Q

Which device is used with multipath diversity to overcome multipath fading?

A

Rake reciever.

37
Q

What is relation between spreading factor and SNR and interference?

A

Low spreading factor reqires higher SNR and causes higher interference.

38
Q

How is bandwidth on demand achieved?

A

With variable spreading factor.

39
Q

What does VSF stand for?

A

Variable spreading factor.

40
Q

What does OVSF stand for? What is its defention? Give one added benifit for it to CDMA? What is its short name? Why is it used?

A

Orthogonal variable spreading factor. Implementation of CDMA and DSSS where spread employs users code. Keeps orthogonality for codes of different length. Channelization code. To identify dedicated physical data channel.

41
Q

What is scrambling code? Why is it used?

A

Codes for cell identification. Reatin retain exact synchronization of OVSF and ensure no interference.

42
Q

What is frame length of long code in scrambling code, its chips count, its chips rate?

A

10 ms frame, 38400 chips, 3.84 Mcps.

43
Q

What are two reasons of varing spreading factor?

A
  1. Enable the final signal to fill the required
    channel bandwidth.
  2. The input data rate may vary from one application to the next and spreading factor varies accordingly.
44
Q

Are channelization codes common to cells

and mobiles?

A

Yes.

45
Q

What is order of application on data for chanilization code and scrambling code at uplink?

A

Chinalization code then scrambling code.

46
Q

What does PN stands for, what is its definiton? For which code is it used?

A

Pseudorandom noise. Signal without recognizable pattern in its unit period. Scrambling code.

47
Q

What is Node B? To which part of GSM does it corrospond?

A

It is hardware connects directly to mobile handset. It corrosponds to BTS of GSM.

48
Q

According to slides, what are long codes and short codes from OVSF and PN codes?

A

OVSF are short codes and PN are long codes.

49
Q

What is difference between OVSF and PN in uplink and downlink with respect to count?

A

There are 512 OVSF codes for different node B in downlink. There are millions of long codes for UE in uplink.

50
Q

How UE identifier is augmented with PN code?

A

Code masking.

51
Q

What does USIM stand for? What is its definition?

A

UMTS Subscriber Identity Module. USIM is a chip that contains some subscription-related information, plus security keys.

52
Q

What does CU stand for? What is it?

A

Carrier Unit. USIM.

53
Q

What is Iub? Iur? Uu? Iu? Cu?

A

Interface between node B and RNC. Interface between two RNCs. Interface between Node B and User Equipment (UE). Interface between SGSN and MSC/
VLR from CN and RNC from UTRAN. Interface between USIM and ME.

54
Q

What does RNC stand for? What is its functions? What is its corrospondad at GSM?

A

Radio Network Controller. Controls the radio resources of the Node Bs that are
connected to it. Its function is similar to BSC.

55
Q

What does SGSN stand for? What is its functions? What is other component does it interfece with? What is its corrospondad at circuit switching domain?

A

Service GPRS Support Node. Mobility management, security, and access control functions. It interfaces to HLR. MSC/VLR.

56
Q

What does GGSN stand for? What is its functions? What is its corrospondad at circuit switching domain of CN?

A

Gateway GPRS support node. The point of interface with external packet data networks such as the Internet. GMSC.

57
Q

What does GMSN stand for? What is its functions?

A

Gateway MSC. In order to set up a requested call, the call is initially routed to a gateway MSC, which finds the correct HLR by knowing the directory number of the subscriber.

58
Q

Which components interface with external networks?

A

GGSN and GMSC from CN.

59
Q

What are subsystems of UMTS system, how are they grouped and thier interfaces?

A

UE has USIM and ME interface with each other with Cu. Node Bs from UTRAn interface with UE with Uu.
UTRAN has Node B and RNC. Node Bs interface with RNC with Iub and RNCs interface with each other with Iur. SGS and MSC/VLR from CN interfaces with RNC with Iu.
CN has SGSN, MSC/VLR, GMSC, GGSN and HLR. All connected to each other except GMSC and GGSN. GMSC and GGSN face external networks.

60
Q

What is function of MSC/VLR?

A

MSC switch circuit switching (SC) transactions. VLR holds a copy of the visiting user’s service profile, and the precise info of the UE’s location.

61
Q

What is function of HLR?

A

Stores master copies of users service profiles. Stores UE location on level of MSC/VLR and SGSN.

62
Q

What does CS domain of CN stand for, what are its components? What does PS domain of CN stand for, what are its components?

A

Circuit switching domain. GMSC and MSC/VLR. Packet switching domain. SGSN and GGSN.

63
Q

What are two functions of UTRAN?

A
  • Handles radio like soft handover and RR management.

* Maximization of the commonalities between PS and CS data handling.

64
Q

What does RNS stand for? What are its components?

A

Radio network subsystem. One RNC and one or more node B.

65
Q

What does AC of RR management stand for? What are thier functionalities? Is it at level of connection or network?

A

Admission control. It handles incoming traffic by admiting it if possible and generates its parameters. Network.

66
Q

What does LC of RR management stand for? What are thier functionalities? Is it at level of connection or network?

A

Load control. It manages when load steps up threshold and does counter measures to get it back to normal load. Network.

67
Q

What does PS of RR management stand for? What are thier functionalities? Is it at level of connection or network?

A

It handels non real time traffic of packets. It decides packet transmission start time and bit rate. Network.

68
Q

What does HC of RR management stand for? What are thier functionalities? Is it at level of connection or network?

A

Handover control. It has active set of Node Bs and thier mobiles, makes handover decisions and handles it. Connection.

69
Q

What does PC of RR management stand for? What are thier functionalities? Is it at level of connection or network?

A

Power control. Control and minimize power of interfaces and maintains its quality. Connection.

70
Q

What are different parts of RR management, how are they categorized?

A

Network based: AC, PS and LC.

Connection based: PC and HC.

71
Q

What is near-far problem?

A

Effect of near signal on far signal at reciever..

72
Q

What is open loop power control?

A

Open Loop
In open loop power control, the mobile monitors its received power continuously
and adjusts its transmit power accordingly. The open loop power control is done
solely by the mobile and does not involve the base station at all. In cdma2000, the
open loop power control on three types of reverse physical channels: R-EACH, RCCH, and reverse traffic channels (R-DCCH, R-FCH, and R-SCH). For each of these
channels, the open loop power control is performed in two separate parts: (1) the MS
calculates the pilot channel transmit power of the R-PICH, which is almost active,
and (2) the MS calculates the traffic channel transmit power of the reverse channels
themselves.
2. Closed Loop
For the reverse link, the closed loop power control of cdma2000 is similar to that
of IS-95. To power control the reverse li

73
Q

What is open loop power control? When is its used?

A

In reverse link, mobile monitors its received power continuously and adjusts its transmit power accordingly. It does not involve the base station. For initial power setting or when
feedback channel is not available.

74
Q

What is Eb/No? What do FER and SIR stand for?

A

SNR normalized by bits per frequency. Frame error ratio. Signal-to-interference ratio.

75
Q

What is close loop power control? What is its loop bandwidth? What is its other name?

A

Base station continuously monitors the link and measures its link quality. If the link quality, or its SIR, starts to get worse, then the base station will command the mobile, via the forward link, to power up. If the link quality becomes too good, then there is excess power on the reverse link and will command the mobile to power down. 1.5kHz. Fast power control.

76
Q

What is outer loop power control?

A

MS, RNC accourding to slides, sets Eb/No, or Sr, for Node B to keep acceptable FER, or BER, at forward link.

77
Q

What is softer handover? What device does combine channels?

A

UE is in overlapping area of two sectors of one Node B and use two channels which are combined by rake reciever.

78
Q

What is soft handover?

A

UE is in overlapping area of two Node Bs. At downlink, rake receiver combines signal. At uplink, each Node B relays signal, with frame reliability indicato, to RNC for selective combination.

79
Q

What are handover types does UMTS support?

A

Soft handover and softer handover.

80
Q

What does HSDPA stand for? what is its definition? What are its features and improvements? Which 3GPP version did introduce it? What is its bit rate?

A

High speed downlink packet access. It is one of two protocols of high speed packet access (HSPA) group which is protocols group for 3G enhance at physical layer. It supports Hybrid ARQ, adaptive coding and modulation and selects cell faster. 3GPP release 5. Peak data rates of 14.0 Mbit/s

81
Q

What does HARQ stand for? What is its defintion, soft combining method definition, its two methods? What does it replace?

A

Hybrid ARQ. ARQ with FEC. Incorrectly received codeword are kept and combined with successive codeword. VSF.

82
Q

What are two methods of HARQ soft combining?

A

Incremental redundancy and chase combining.

83
Q

What is definition of incremental redundancy?

A

Resend data frame with different bits of codeword generation. According to slides, only recalculated bits are sent without dataword.

84
Q

What one way of HSDPA accomplishes fast scheduling?

A

It is controlled by Node B rather than RNC.

85
Q

What are improvements of 3.5G over 3G in transmission time interval, modulation methods and data rate

A

Frame transmission time interval is 2 ms instead of 10 ms. Modulation methods are QPSK and 16QAM instead of only QPSK. Peak data rates of 14.0 Mbit/s instead of 2 Mbps.

86
Q

What are implemented and standard data rates for voice GSM, GPRS, EDGE, WCDMA and HSDPA? What are thier linetime, add to them EUL or HSUPA?

A

9 kbit/s and 13 kbit/s, upto 40 kbps and standard allows upto 171 kbps, 120 kbps and standards allow upto 473 kbps, upto 384 kbps and standards allow upto 2 Mbps and 10 Mbps and standard allows upto 14.4.
GSM then GPRS on 2000 and 2001 then EDGE then WCDMA on 2003 and 2004 then HSDPA on 2005 and 2006 then EUL on 2007 and 2008.

87
Q

What does GERAN stand for? What is its defenetion?

A

GSM EDGE radio access network. Radio of between BS and BSC at GSM and EDGE together network.

88
Q

Can MS of GSM or GPRS uses BS of different network.

A

Yes. EGPRS incorporated its base stations with GSM base stations.

89
Q

Does GSM use circuit or packet switching method? Does GPRS use circuit or packet switching method?

A

GSM uses circuit switching method.GPRS uses packet swithing method.

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