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ECE150 (Mobile Embedded Systems) > Cellular Standards (LTE) > Flashcards

Cellular Standards (LTE) Flashcards

1
Q

What multiplexing method does 1G uses

A

Frequency Division Multiple Access (FDMA)

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2
Q

What are the foundation of mobile communication?

A
  • Licensed Spectrum
  • Frequency Resues
  • Mobile Network
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3
Q

What is Licensed Spectrum?

A

Cleared spectrum for exclusive use by mobile technologies and deployed by base stations.

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4
Q

What is Frequency Reuse?

A

Reusing frequency without interference through geographical separation.
Neighboring cells operate on different frequency to avoid interference

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5
Q

What is mobile network?

A

Coordinated network for seamless access and seamless mobility
Integrated transparent backhaul network.

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6
Q

What is Mobile 2G?

A

GSM: Medium access - time and frequency division
Data rate: 9.6 kbps to support voice calls and SMS
Subscriber Identity Module (SIM) is introduced

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7
Q

What are the components of Mobile 2G: Code Division Multiple Access?

A
  • Near-Far Power Challenge
  • Cell-Edge Challenge
  • Multipath Fading Challenge
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8
Q

What is Near-Far Power Challenge?

A

Users closer to the tower over power the uplink signal minimizing capacity on the shared channel.
Solution: Continuous control of transmit power based on signal strength

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9
Q

What is Cell-Edge Challenge?

A

Interference caused by users in close proximity, on the same frequency, and communicating with different towers.
Solution: Users simultaneously communicate with multiple towers at cell edge

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10
Q

What is Multipath Fading Challenge

A

Interference caused by the reception of the same signal over multiple paths resulting in poor signal to noise ratio
Solution: Advanced receivers combine energy of multiple signal paths

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11
Q

What is Shannon’s Law?

A

C = Wnlog_2(1+SNR)

Capacity, Spectrum, antennas, signal quality

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12
Q

How does LTE Architecture work?

A
  • EPC takes overall control of UE (User equipment)

- E-UTRAN controls radio functions

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13
Q

What are the elements of EPC?

A

Evolved Packet Core

  • Packet Data Network Gateway (P-GW)
  • Serving Gateway (S-GW)
  • Mobility Management Entity (MME)
  • Home Subscriber Server (HSS)
  • Policy Control & Charging Rules Function (PCRF)
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14
Q

What is P-GW

A
  • IP address allocation for UE

- Mobility anchor for non-3GPP handover

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15
Q

What is S-GW

A
  • Packet routing and forwarding

- Mobility anchor for inter-eNodeB handover

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16
Q

What is MME

A
  • User authentication

- Roaming

17
Q

What is HSS

A

Database containing the user’s subscription

18
Q

What is PCRF

A

QoS and charging policy control

19
Q

What is EPS?

A

Evolved Packet Core network is comprised of EPC and E-UTRAN

20
Q

What are LTE Components?

A
  • Orthogonal Frequency Division Multiple Access (OFDMA)
  • Multiple Input Multiple Output (MIMO)
  • Handover and packet forwarding
  • Multimedia Broadcast Multicast Services (MBMS)
21
Q

What is OFDM?

A

Parallel data transmission on several orthogonal subcarriers with lower rate

22
Q

What is OFDMA?

A
  • `Assign subsets of subcarriers to multiple users

- Enables adaptive carrier allocation, high spectral efficiency, and little interference between subcarriers.

23
Q

What is MIMO?

A

Multiple antennas at the transmitter and receiver

  • Channel feedback helps combat fading
  • Matrix form Y = HX + W
  • Increased data rate
24
Q

What is handover and packet forwarding?

A

Data loss is prevented during handover by packet forwarding process that buffers and transfers undelivered data

25
Q

What is MBMS?

A

Point to multipoint interface specification

- Target applications: Mobile TV, Radio broadcasting, live streaming video services, and emergency alerts

26
Q

What are components of LTE Advanced

A
  • Inter-cell interference coordination
  • dynamic subcarrier assignment
  • coordinated multiple point
  • carrier aggregation
  • heterogeneous networks
27
Q

What is FFR?

A

Fractional Frequency Reuse separates frequency bands and allocates the bands efficiently to prevent signal interference from adjacent base stations

28
Q

What is DSA

A

Subcarriers experience different channel conditions due to frequency selective fading.
DSA dynamically allocates subcarriers based on channel state

29
Q

What is CoMP

A
  • Multiple base stations simultaneously communicate with user
  • MIMO scheme where multiple input part is coming from different base station
30
Q

What is CA

A

Carrier Aggregation combines individual component carriers to increase data rate and capacity of the networks

31
Q

What are the three modes of CA in LTE-A

A
  1. Intra-band contiguous
  2. Intra-band non-contiguous
  3. Inter-band
32
Q

What is HetNet?

A

Macro cell provides a few miles of wide area coverage and small cells can be categorized by their coverage: Microcell, Picocell, Femtocell, etc

ECE150 (Mobile Embedded Systems) (12 decks)

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