Cellular COMMUNICATIONS

fearlessquickMobile - Wireless

Dec 12, 2013 (3 years and 11 months ago)

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CELLULAR
COMMUNICATIONS

LTE

Data Rate

Requirements And Targets to LTE


reduced delays, in terms of both connection establishment
and transmission latency;


increased user data rates;


increased cell
-
edge bit
-
rate, for uniformity of service
provision;


reduced cost per bit, implying improved spectral efficiency;


greater flexibility of spectrum usage, in both new and pre
-
existing bands;


simplified network architecture;


seamless mobility, including between different radio
-
access
technologies;


reasonable power consumption for the mobile terminal

Cell/User Throughput


Average cell throughput [bps/cell] and spectral
efficiency [bps/Hz/cell].


Average user throughput [bps/user] and spectral
efficiency [bps/Hz/user].


Cell
-
edge user throughput [bps/user] and spectral
efficiency [bps/Hz/user].


The metric used for this assessment is the 5
-
percentile
user throughput, obtained from the cumulative
distribution function of the user throughput.

Key Performance Requirements

Key Performance Requirements

Multiple Antenna Technology


Diversity gain.
Use of the space
-
diversity provided by
the multiple antennas to improve the robustness of the
transmission against multipath fading.


Array gain.
Concentration of energy in one or more
given directions via
precoding

or
beamforming
. This
also allows multiple users located in different directions
to be served simultaneously (so
-
called multi
-
user
MIMO).


Spatial multiplexing gain.
Transmission of multiple
signal streams to a single user on multiple spatial layers
created by combinations of the available antennas.

MIMO

Packet
-
Switched Radio Interface


Completely Packet Oriented Systems

LTE User Equipment

Network

The Access Network

Bearers


Minimum Guaranteed Bit Rate (GBR) bearers
which can be used for applications
such as VoIP.


have an associated GBR value for which dedicated
transmission resources are permanently allocated


Non
-
GBR bearers which do not guarantee any
particular bit rate.



web browsing or FTP transfer.


bandwidth resources are allocated permanently to the
bearer.

QoS

Handover

Lossless Handover

Logical and Physical Channel

Discontinuous Reception(DRX)


Reduce time in a reception mode in order to save
battery

Logical Channel Priority

OFDM

OFDM

Peak
-
To
-
Average Power Ratio



PAPR





Power amplifiers that are linear at wide range of
inputs are costly



Handset: Reduce PAPR

OFDMA

OFDMA/TDMA

Physical Layer

Channel Estimation



Transmission distort the signal and add noise





If transmitted signal is known, can estimate
distortion and apply inverse transformation on other
signals



Reference signal

Reference Signal

Two antennas

Link Adaptation

Channel Quality Indicator

Multiple Antenna

Multiple Antenna

Optimal Power Allocation

Multi
-
User Scheduling

Resource Scheduler

Partial Frequency Reuse

Partial Frequency Reuse

Handover

40

Evolution of the Radio Interface

EDGE EDGE+

W
-
CDMA HSPA HSPA+

2000

LTE




LTE
-
Advanced

40

2010

384Kb/s

1Mb/s

384Kb/s

42Mb/s

18Mb/s

100Mb/s

1000Mb/s

Standards availability