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Enhancement of data rates using

scheduling algorithms and

improved Air-interface for LTE

By

Mohankumar N. M.

Under the Guidance of

Dr. J.T. Devaraju

Associate Professor

The Dept. of Electronic Science

Bangalore University


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Applications with increasing datarates


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Fundamental Constraints

Shannons capacity upper bound

Achievable data rate is fundamentally limited bybandwidth and signal-to-noise ratio (SNR).


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Evolution of mobile technologies


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3GPP (3rd Generation Partnership

Project).

3GPP is a partnership of 6 regional standards

organizations.

ARIB (Japan)

ATIS (USA) CCSA (China)

ETSI (Europe)

TTA (South Korea)

TTC (Japan)


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3GPP Evolution

Release 99 (2000): UMTS/WCDMA

Rel-5 (2002): HSDPA

Rel-6 (2005): HSUPA

Rel-7 (2007) and beyond: HSPA+

Long Term Evolution (LTE)

3GPP work on the Evolution started in November 2004.

Standardized in the form of Rel-8 (Dec. 2008).

LTE-Advanced (LTE-A)More bandwidth (up to 100 MHz) and backward

compatible with LTE.

Standardized in the form of Rel-10 (Mar. 2011).

Meets IMT-Advanced requirements: Real 4G.


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Characteristics of 3GPP Technologies


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Evolved Node B (eNB)Supports air interface

Provides radio resourcemanagement functions

Mobility Management Entity(MME)

Manages mobility and providessecurity

Operates in control plane andprovides authentication

Serving Gateway (SGW)

Provides Mobility

Responsible for Routing andForwarding

Packet Data Network Gateway(PDN GW)

Provides connectivity to Internet

Provides QoS and mobility between

3G and non-3G networks

LTE network Architecture


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LTE Specifications


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LTE-Advanced Requirements

Peak data rate:

1 Gbps DL and 500 Mbps UL

Latency

Less than 10 ms within Connected mode Less than 50 ms from Idle to Connected mode

Spectrum

Up to 100 MHz bandwidth

Support for non-consecutive bands (spectrum

aggregation)

Peak spectrum efficiency

30 bps/Hz DL and 15 bps/Hz UL


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4G Enabling Technologies

OFDM/OFDMA

Frequency domain equalization

SC-FDMA

MIMO

Fast channel-dependent resource scheduling


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Orthogonal Frequency Division

Multiple Access

OFDMA is a multi-user access scheme using OFDM.

Each user occupies a different set of subcarriers.

Scheduler can exploit frequency-selectivity and multi-user

diversity.


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Single Carrier FDMA

SC-FDMA is a new multiple access technique.

Utilizes single carrier modulation, DFT-spread orthogonal

frequency multiplexing and frequency domain equalization.

It has similar structure and performance to OFDMA.

SC-FDMA is currently adopted as the uplink multiple

access scheme in 3GPP LTE.


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MIMO

Multiple input multiple output (MIMO) technique

improves communication link quality and capacity by

using multiple transmit and receive antennas.

Two types of gain; spatial diversity gain and spatialmultiplexing gain.


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LTE-A: Relaying

Improves coverage and cell-edge performance.

Relay node is wirelessly connected to RAN via a

donor cell.


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conclusion

LTE supports high speed internet, robust

gaming, 3-D TV etc. with high data-rate,

spectral flexibility, low latency, improved

coverage and battery lifetime. The IP-based

flat multi-core network architecture provides

seamless mobility and advanced QoS

mechanism.

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