07-02-2013, 03:42 PM
Overview of 3GPP LTE-Advanced Carrier Aggregation for 4G Wireless Communications
[attachment=50050]
ABSTRACT
To satisfy the ever increasing demand for
higher throughput and data rates, wireless communication
systems need to operate in wider
bandwidths. 3GPP LTE-Advanced with carrier
aggregation enables operators to maximally and
optimally utilize their available spectrum
resources for increased data rates and user experience
while reducing their incurred OPEX and
CAPEX. This article provides a tutorial overview
of 3GPP LTE-Advanced with carrier aggregation
as specified in Rel-10 including deployment scenarios
of interest, main design features,
PHY/MAC procedures, and potential enhancements
for future standard releases.
INTRODUCTION
In recent years the telecommunication industry
witnessed a boom in packet-based data application
services. Providing high quality of service
for mobile applications in a cost-effective manner
becomes increasingly important for operators
to meet consumer needs. Toward this end,
the International Telecommunication Union
(ITU) initiated a global standard initiative, IMTAdvanced,
for international mobile telecommunications
in October 2007 [1]. IMT-Advanced
systems include exciting new capabilities for providing
a wide range of telecommunication services
and applications, stressing improved quality
of service and worldwide development. To support
enhanced user and service demands, peak
data rate targets of 100 Mb/s for high mobility
and 1 Gb/s for low mobility are established for
IMT-Advanced. In addition, IMT-Advanced
strives for key features such as functional commonality,
intersystem operability, global roaming,
and user-friendly application.
CARRIER AGGREGATION
DEPLOYMENT SCENARIOS
Generally, carrier aggregation systems are
deployed to improve data rates for users within
overlapped areas of cells. The following deployment
scenarios [7] are considered during the
design of LTE-Advanced carrier aggregation,
exemplified with two component carriers at frequencies
of F1 and F2 as shown in Fig. 1.
Deployment scenario 1: Cells with carrier frequencies
F1 and F2 are collocated and overlaid
with F1 and F2 in the same band. Nearly the
same coverage is provided on both carriers due
to the similar path loss within a same band.
Mobility is supported on either carrier. Higher
data rates are achievable throughout the cell by
carrier aggregation.
Deployment scenario 2: Cells with carrier frequencies
F1 and F2 are collocated and overlaid
with F1 and F2 in different bands. Different coverage
is provided on different carriers due to the
larger path loss in the higher frequency band.
Mobility is supported on the carrier in the lower
frequency band providing sufficient coverage.
The carrier in the higher frequency band is used
to improve data rates and throughput.
HIGHER LAYER ASPECTS
The services provided by higher layers are fulfilled
by user plane and control plane functions.
The user plane is responsible for data communicationl,
and the control plane is responsible for
maintaining the connection between the network
and the UE. LTE-Advanced carrier aggregation
inherits the LTE Release 8/9 user plane and
control plane design to maintain backward compatibility.
To efficiently utilize the multiple component
carriers for data transmission, additional
procedures, including cell management and cell
activation/deactivation, are designed in LTEAdvanced
carrier aggregation.
CELL MANAGEMENT
Cell management is the control procedure
enabling the network to add/remove/change an
SCell or to switch the PCell of UE. An
RRC_IDLE UE unit establishes an RRC connection
toward a serving cell, which automatically
becomes its PCell. Depending on the carrier
where initial access is performed, different UE
units in a carrier aggregation system may have
different PCells. With the RRC connection on
the PCell, the network can further configure one
or more SCells for UE within the UE capability
of carrier aggregation to meet traffic demands.
The necessary information, including system
information, of an SCell is conveyed to the UE
via dedicated RRC signaling. Addition, removal,
and reconfiguration of SCells to a UE unit are
also performed via dedicated RRC signaling. The
network can further change the PCell of a UE,
for example, to improve the link quality of the
PCell on which critical control information is
sent or to provide load balancing among different
SCells.
CONCLUSIONS
This tutorial article provides an overview of
LTE-Advanced carrier aggregation. Apart from
the benefit of data rate increase, carrier aggregation
enables efficient spectrum resource utilization
in various deployment scenarios.
LTE-Advanced carrier aggregation inherits the
key designs of LTE Release 8/9 per component
carrier, thereby maintaining the advantages of
LTE Release 8/9, and reducing the specification
and implementation efforts for faster product
availability and system deployment. As spectrum
resources become scarcer, carrier aggregation
will continue to be an important technique in
future communication syste
[attachment=50050]
ABSTRACT
To satisfy the ever increasing demand for
higher throughput and data rates, wireless communication
systems need to operate in wider
bandwidths. 3GPP LTE-Advanced with carrier
aggregation enables operators to maximally and
optimally utilize their available spectrum
resources for increased data rates and user experience
while reducing their incurred OPEX and
CAPEX. This article provides a tutorial overview
of 3GPP LTE-Advanced with carrier aggregation
as specified in Rel-10 including deployment scenarios
of interest, main design features,
PHY/MAC procedures, and potential enhancements
for future standard releases.
INTRODUCTION
In recent years the telecommunication industry
witnessed a boom in packet-based data application
services. Providing high quality of service
for mobile applications in a cost-effective manner
becomes increasingly important for operators
to meet consumer needs. Toward this end,
the International Telecommunication Union
(ITU) initiated a global standard initiative, IMTAdvanced,
for international mobile telecommunications
in October 2007 [1]. IMT-Advanced
systems include exciting new capabilities for providing
a wide range of telecommunication services
and applications, stressing improved quality
of service and worldwide development. To support
enhanced user and service demands, peak
data rate targets of 100 Mb/s for high mobility
and 1 Gb/s for low mobility are established for
IMT-Advanced. In addition, IMT-Advanced
strives for key features such as functional commonality,
intersystem operability, global roaming,
and user-friendly application.
CARRIER AGGREGATION
DEPLOYMENT SCENARIOS
Generally, carrier aggregation systems are
deployed to improve data rates for users within
overlapped areas of cells. The following deployment
scenarios [7] are considered during the
design of LTE-Advanced carrier aggregation,
exemplified with two component carriers at frequencies
of F1 and F2 as shown in Fig. 1.
Deployment scenario 1: Cells with carrier frequencies
F1 and F2 are collocated and overlaid
with F1 and F2 in the same band. Nearly the
same coverage is provided on both carriers due
to the similar path loss within a same band.
Mobility is supported on either carrier. Higher
data rates are achievable throughout the cell by
carrier aggregation.
Deployment scenario 2: Cells with carrier frequencies
F1 and F2 are collocated and overlaid
with F1 and F2 in different bands. Different coverage
is provided on different carriers due to the
larger path loss in the higher frequency band.
Mobility is supported on the carrier in the lower
frequency band providing sufficient coverage.
The carrier in the higher frequency band is used
to improve data rates and throughput.
HIGHER LAYER ASPECTS
The services provided by higher layers are fulfilled
by user plane and control plane functions.
The user plane is responsible for data communicationl,
and the control plane is responsible for
maintaining the connection between the network
and the UE. LTE-Advanced carrier aggregation
inherits the LTE Release 8/9 user plane and
control plane design to maintain backward compatibility.
To efficiently utilize the multiple component
carriers for data transmission, additional
procedures, including cell management and cell
activation/deactivation, are designed in LTEAdvanced
carrier aggregation.
CELL MANAGEMENT
Cell management is the control procedure
enabling the network to add/remove/change an
SCell or to switch the PCell of UE. An
RRC_IDLE UE unit establishes an RRC connection
toward a serving cell, which automatically
becomes its PCell. Depending on the carrier
where initial access is performed, different UE
units in a carrier aggregation system may have
different PCells. With the RRC connection on
the PCell, the network can further configure one
or more SCells for UE within the UE capability
of carrier aggregation to meet traffic demands.
The necessary information, including system
information, of an SCell is conveyed to the UE
via dedicated RRC signaling. Addition, removal,
and reconfiguration of SCells to a UE unit are
also performed via dedicated RRC signaling. The
network can further change the PCell of a UE,
for example, to improve the link quality of the
PCell on which critical control information is
sent or to provide load balancing among different
SCells.
CONCLUSIONS
This tutorial article provides an overview of
LTE-Advanced carrier aggregation. Apart from
the benefit of data rate increase, carrier aggregation
enables efficient spectrum resource utilization
in various deployment scenarios.
LTE-Advanced carrier aggregation inherits the
key designs of LTE Release 8/9 per component
carrier, thereby maintaining the advantages of
LTE Release 8/9, and reducing the specification
and implementation efforts for faster product
availability and system deployment. As spectrum
resources become scarcer, carrier aggregation
will continue to be an important technique in
future communication syste