LTE AND WI-FI COEXISTENCE IN UNLICENSED BANDS

1. LTE AND WI-FI COEXISTENCE
IN UNLICENSED BANDS
American University of Culture and Education (AUCE)
Nabatieh Campus
Mobile Communications CSI542
Instructor Name: Abbas Nasser
Students names: Ali Saad And Mostafa Abbas
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2. Introduction
Therefore, it is necessary for LTE to “fairly” coexist with such technologies in the
targeted unlicensed spectrum.
The telecom industry and standardization bodies have made many attempts at
increasing the capacity of LTE networks.
A solution to overcome the scarcity of spectrum is to extend LTE by introducing
the capability to directly exploit the unlicensed spectrum.
The targeted band is the 5 GHz U–NII (Unlicensed National Information
Infrastructure).
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3. But, gaining capacity in a range where Wi-Fi is in widespread use and
ensuring fairness between systems is not an easy problem to address.
With the rapid growth of mobile data, many LTE operators are interested
in leveraging unlicensed bands.
The purpose is to enhance data rates and user experience and to overcome
the lack of spectrum resources.
Challenges
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4. LTE VS. WI-FI
Comparison of LTE Wi-Fi
1. Channel access
Centralized controller
On DL/UL. LTE
does not contend
Contention based Distributed
Coordination Function (DCF)
2. Channel usage
Continuous frames,
always on
On-demand, on and of
3. Scheduling
The channel is shared by
multiple users at time
and frequency domains
One user uses the
entire channel at a time
4. Interference
Co-tier/cross-tier
co-channel interference
Hidden/exposed
terminal, collision
5. Retransmission
mechanism
HARQ combining is used
in retransmission
in retransmission
Single-loop ARQ with ACK
can be used
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5. Standardization efforts
Initialization &
Configuration
Channel
Selection
Clean
Channel
?
Full Duty
Cycle
CSAT
Low
Load?
Secondary
Carrier Off
YES
NO
NO
YES
As previously mentioned, Qualcomm firstly
presented a functional prototype for an LTE cell
working in the 5 GHz band based on 3GPP
Release. Such a prototype required very small
changes to standard LTE equipment and the
adopted technology was called LTE–U.
Three mechanisms:
• Channel Selection.
• Carrier Sense Adaptive Transmission (CSAT).
• Opportunistic Supplemental Downlink (SDL).
LTE-U
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6. Standardization efforts
What is LTE License Assisted Access (LAA)?
Is a feature of LTE that leverages the unlicensed 5 GHz band in combination with licensed
spectrum to deliver a performance boost for mobile device users.
It uses carrier aggregation in the downlink to combine LTE in unlicensed 5 GHz band with
LTE in the licensed band to provide better data rates and a better user experience.
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7. Standardization efforts
Advantages of LTE-LAA Technology
 Consumers can leverage the combination of licensed and unlicensed bands to achieve
higher peak rates indoor and outdoor.
 By distributing traffic between the licensed and unlicensed bands, LAA frees up capacity
on the licensed spectrum, benefiting users on those bands.
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8. Standardization efforts
MuLTEfire
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9. Conclusion
The performance issues deriving from the coexistence of Wi-Fi and LTE in the unlicensed
bands are attracting much interest lately, both from the research community and
standardization bodies. In this presentation, we presented the solutions the
standardization bodies are developing: LTE–U, LAA.
in the future, You can expect speeds above 100 Mbps under good conditions on licensed
LTE networks. Even higher speeds will become possible where unlicensed spectrum and
infrastructure become available.
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