wiki:Other/Summer/2015/aSDR3

LTE Unlicensed (LTE-U)

Table of Contents

  1. 2015 Winlab Summer Internship
    1. Projects
    1. Indoor Localization
    2. Introduction
      1. Motivation
      2. What is ORBIT Lab?
      3. Overall Approach
      4. Resources
      5. Procedure
      6. Plan of Action
      7. Weekly Presentations
      8. Team
    1. SDR in ORBIT: Spectrum Sensing
      1. Introduction
      2. Team
      3. Objectives
      4. Weekly Progress
      5. Experiments
    1. LTE Unlicensed (LTE-U)
      1. Introduction
      2. Objectives
      3. Theory
      4. Analyzing Tools
      5. Experiment 1: Transmit and Receive LTE Signal
      6. Experiment 2: The Waterfall Plot
      7. Experiment 3: eNB and UE GUI
      8. Experiment 4: Varying Bandwidths
      9. Experiment 5: Working with TDD or FDD
      10. Experiment 6: TDD with Varying Bandwidths
      11. Experiment 7: TDD Waterfall Plot
      12. Poster
      13. Members
      14. Materials
      15. Resources
    1. Distributed Simulation of Power Grid
      1. Introduction
      2. Objectives
      3. People
      4. Resources
    1. Context-Aware IoT Application on MobilityFirst
      1. Introduction
      2. Objectives
      3. System Architecture
      4. Network Diagram
      5. Experiment Tools
      6. Results
      7. Future Work
      8. Team member
    1. Real-Time Cyber Physical Systems Application on MobilityFirst
      1. Github Repo
      2. Introduction
      3. Preliminary Goal
      4. Outline of the Project
      5. Tasks
      6. Image Processing
      7. Weekly Summary
      8. Team
      9. Presentation Slides
    1. GNRS Assited Inter Domain Routing
      1. Introduction
    1. GNRS Management
      1. Introduction
      2. Work Milestones
    1. Effective Password Cracking Using GPU
      1. Introduction
      2. Objectives
      3. GPU
      4. Experiment
      5. Tools and Resources
  2. Body Sensor Networks
    1. Introduction
    2. Project Overview
    3. Data Collection
      1. Initial BCI data
    4. Data Analysis
    5. Tools/ Resources
    1. Unity Traffic Simulation
      1. Introduction
      2. Objectives
      3. People
    1. Mobile Security
      1. Introduction
      2. Motivation
    2. Resources
  3. Dynamic Video Encoding
    1. Introduction
    2. Goals
    3. Background Information
      1. Anatomy of a Video File
      2. What is a CODEC?
      3. H.264 Compression Algorithm
      4. Scalable Video Coding
      5. Network Emulator Test Results
      6. DASH Multi-Bitrate Encoding
      7. DASH Content Generation
      8. Bitrate Profiles
      9. Video Encoding Algorithms
      10. GPAC
    4. Presentations
    5. People

Introduction

Long-Term Evolution (LTE) is the latest high-speed data standard of wireless communication. It is usually known as 4G LTE in cellphone or mobile devices.

LTE in Unlicensed (LTE-U) operates in open/unlicensed spectrum, such as in the 5GHz band. It aggregates with the licensed LTE in order to increase the data rate of the Advanced LTE system (unlicensed and licensed LTE system).

With the massive growth in data traffic and mobile devices, it is necessary to expand the mobile network system. While the licensed spectrum is limited in amount, the possible solution should be using the available unlicensed spectrum, even it might be conflict with the exist network, such as Wi-Fi.

It is recently proposed by Qualcomm, Ericsson, and Verizon that LTE-U should be utilize in unlicensed spectrum on the 5725-5850 MHz band so that it could be a "nice neighbor" with Wi-Fi.

Objectives

  • Research on wireless communications, LTE, LTE-U and Wi-Fi in advance
  • Simulate the LTE-U base station in ORBIT Lab using OMF commands, WiMax, and OpenAirInterface
  • Transmit and Receive LTE Signal
  • Apply analyzing tools, such as spectrum analyzer, GNU Radio, SNR
  • Modify OAI source code and report the result

Theory

OpenAirInterface (OAI) is open-source based experimental research. It allows to simulate the digital communication environments, such as LTE. OAI Documentation

Real-world testbed:

  • OAI SW + OAI HW or USRP B210/X300
  • OAI EPC + OAI eNB <–> COTS UE
  • Commercial/3rd party EPC + OAI eNB <–>COTS UE
  • OAI eNB <–>OAI UE
  • OAI + Signal generator/spectrum analyzer

The source code OpenAir4G is organized into 6 main repositories for different use cases: OpenAir1, OpenAir2, OpenAir3, OpenAir0, OpenAirCN, Targets.

Each repository focuses on a different data communication layer or focus of 3GPP implementation.

http://www.orbit-lab.org/raw-attachment/wiki/Other/Summer/2015/aSDR3/OpenAirInterface.png

OpenAir1 Code
  • Open-source real-time and offline Software
  • Baseband DSP SIMD-x86 routines for implementing LTE UE’s and eNB’s
  • Simulation TestBenches for all LTE PHY/transport channels
    • Sensing Localization Techniques
    • PHY modeling tools
    • Propagating Measurement and Modeling
    • Basic DSP Routines for implementing LTE specifications
  • Sounding Software, Physical (PHY) Abstraction Software, and Channel Simulation
    • Sound Software - Eurecom’s Multi-Input Multi-Output (MIMO) OpenAir Sounder (EMOS) allows multiuser MIMO channel measurements in real time and store measurements from both user equipment(UE) and evolved NodeB(eNB)
    • PHY Abstraction Software contains all real-time/simulation signal processing, unitary TestBenches for the different channel coders and decoders, and modulation/demodulation (includes FFT/SC-FDMA front-end processing)
    • Channel Simulation Software contains simulation routines to test PHY, and TestBenches for unitary simulation of physical channels, and full system simulation, such as PHY, MAC (medium access control), RLC (radio link control), RRC (radio resource control), PDCP (packet data convergence protocol)
OpenAir2 Code
  • Open-source real-time and offline Software
  • Contains LTE MAC (36-213), RLC (36-322), PDCP (36-323), and two RRC implementations
    • LLC establishes/controls logical links between local devices on a network
    • MAC controls access to the network medium to avoid conflicts
    • Data Framing is responsible for final encapsulation of messages into frames
    • Addressing labels information with a particular destination location
    • Error Detection and Handling
  • S1 interfaces for user and control planes of the eNB, X2 Application Protocol (X2AP), and OAI network driver
OpenAir3 Code
  • Open-source Linux Software suite for cellular and MESH networks
  • Provides scripts and adaptations for the Linux networking suite
  • Contains OAI-MME (Mobility Management Entity), which is responsible for authentication of the mobile devices
    • Network Access Control manages authorization for UEs, allow to gain IP connectivity
    • Radio Resource Management decides radio resource management strategy (RRM)
    • Mobility Management provides seamless inter-working with multiple use cases such as Inter-eNB
    • Roaming Management supports outbound/inbound roaming subscriber
    • UE Reach-ability manages communication with the UE and HSS
    • Tracking Area Management allocates tracking area identity list to UE
    • Lawful Intercept
    • Load Balancing Between S-GWs
OpenAir0 Code
  • Open-source real-time Hardware & Software for different Xilinx targets
OpenAirCN Code
  • 3GPP-EPC implementation
  • Small-scale 3GPP-EPC implementation
  • Includes MME, P and S-Gateway, and HSS components
Targets Code
  • Top-level target designs for use with and without Hardware in emulated or real-time modes

Analyzing Tools

Spectrum Analyzer
Category Hardware Spectrum Analyzer – Tektronix SA2600 Software Spectrum Analyzer – RTLSDR Scanner

Characteristics

Wire Measurement must be connect with 30dB attenuator to avoid saturation PROS user-friendly, convenient, remote access, software-based spectrum analyzer
Wireless Measurement requires much higher gain than using wire CONS Realtek 2832 EZCap can’t tune to frequencies higher than 1.8GHz
Graphs http://www.orbit-lab.org/raw-attachment/wiki/Other/Summer/2015/aSDR3/Tektronix(1).png http://www.orbit-lab.org/raw-attachment/wiki/Other/Summer/2015/aSDR3/RTLSDR(1).png
GNU Radio

GNU Radio is an important software-based tool, being used to obtain the FFT Plot, the Constellation Plot, and the Waterfall Plot. How to use GNU Radio

Signal-to-Noise Ratio (SNR)

There are 2 methods to approximate the SNR:

  • Method 1 Estimate the noise power by measuring the received signal power when transmitter is turned off.
  • Method 2 Estimate the noise power by calculating the received signal variance.

http://www.orbit-lab.org/raw-attachment/wiki/Other/Summer/2015/aSDR3/SNR.png

SNR Estimation MATLAB Program: http://www.orbit-lab.org/raw-attachment/wiki/Other/Summer/2015/aSDR3/SNR.2.png

Experiment 1: Transmit and Receive LTE Signal

The experiment is simulated in Sandbox 1 with USRP Hardware Driver (UHD) using OpenAirInterface (OAI) software.

Figure 1a. Received LTE Signal ASCII Plot

The left figure shows the overview of the received LTE signal: the carrier and the sidebands. The right figure indicates clearly that there are noises in both the carrier and the sideband.

The SNR can be quickly estimated by taking the average of the carrier or (around -50dB) and subtract by the average of the sideband (around -90dB). Thus, the SNR should be approximately 40dB.

The SNR calculated by the MATLAB Program gives a very close result: 38.8 dB

Figure 1b. I/Q Samples

Note:

  • PSS Primary Synchronization Signal
    • Transmitted twice per 10 ms radio frame
    • Uses sequence known as Zadoff-Chu
    • Sequence of length 62
  • SSS Secondary Synchronization Signal
    • Uses sequence known as M-sequence
    • 2 Binary sequences of length 31
  • CFI Control Format Indicator
  • CSRS Cell Specific Reference Signal

Experiment 2: The Waterfall Plot

The experiment is simulated in GNU Radio and Spectrum Analyzer (Tektronix SA2600) after activating the LTE eNB Base Station to transmit signal.

Figure 2a. GNU Radio Block Diagram
Figure 2b. The Constellation Plot
Figure 2c. The FFT obtained from GNU Radio (left) and Tektronix SA2600 (right)
Figure 2d. The Waterfall Plot obtained from GNU Radio (left) and Tektronix SA2600 (right)

Experiment 3: eNB and UE GUI

Experiment 4: Varying Bandwidths

http://www.orbit-lab.org/raw-attachment/wiki/Other/Summer/2015/aSDR3/LTE_BW_1.4.png http://www.orbit-lab.org/raw-attachment/wiki/Other/Summer/2015/aSDR3/LTE_BW_5.png
\ http://www.orbit-lab.org/raw-attachment/wiki/Other/Summer/2015/aSDR3/LTE_BW_5.png http://www.orbit-lab.org/raw-attachment/wiki/Other/Summer/2015/aSDR3/LTE_BW_10.png

Experiment 5: Working with TDD or FDD

By varying the E-UTRA band number in the oai.conf file to 41(band compatible with TDD transmissions at 2.66GHz) we were able to observe the difference in the transmission from TDD and the previous experiment of FDD.

Other E-UTRA bands for future experiments can be viewed here

Experiment 6: TDD with Varying Bandwidths

The purpose of this experiment was to view the effects of varying the LTE bandwidth of the transmitted signal. To observe the the effects of increased throughput.

Experiment Procedure: SSH commands

Begin by reserving a spot on SandBox1

ssh dlambros@console.sb1.orbit-lab.org

Welcome to Ubuntu 12.04.5 LTS (GNU/Linux 3.2.0-88-generic x86_64)

 * Documentation:  https://help.ubuntu.com/
New release '14.04.1 LTS' available.
Run 'do-release-upgrade' to upgrade to it.

|-----------------------------------------------------------------|
|                 *** For authorized use only ***                 |
| This system is for the use of authorized users only.  All users |
| are expected to comply with the "Acceptable Use Policy" availa- |
| ble at http://www.orbit-lab.org/AUP.html                        |
| Individuals using this computer system, are subject to having   |
| all of their activities on this system monitored and recorded   |
| by system personnel.                                            |
|                                                                 |
| Anyone using this system expressly consents to such monitoring  |
| and is advised that if such monitoring reveals possible         |
| evidence of criminal activity, system personnel may provide the |
| evidence of such monitoring to law enforcement officials.       |
|                                                                 |
| Email question, comments or problems to help@orbit-lab.org      |
|-----------------------------------------------------------------|

Last login: Wed Aug 19 14:00:13 2015 from static-72-76-98-84.nwrknj.fios.verizon.net
Dlambros@console.sb1:~$ 

Next check that the nodes are powered off

Dlambros@console.sb1:~$ omf stat -t all

 INFO NodeHandler: OMF Experiment Controller 5.4 (git 5dd7e2c)
 INFO NodeHandler: Reading configuration file /etc/omf-expctl-5.4/services.yaml
 INFO NodeHandler: Add domain http - http://internal1.orbit-lab.org:5054/
 INFO NodeHandler: Add domain http - http://repository1.orbit-lab.org:5054/
 INFO NodeHandler: Add domain http - http://external1.orbit-lab.org:5054/
 INFO NodeHandler: Slice ID: default_slice (default)
 INFO NodeHandler: Experiment ID: default_slice-2015-08-19t14.54.21.510-04.00
 INFO NodeHandler: Message authentication is disabled
 INFO Experiment: load system:exp:stdlib
 INFO property.resetDelay: resetDelay = 230 (Fixnum)
 INFO property.resetTries: resetTries = 1 (Fixnum)
 INFO Experiment: load system:exp:eventlib
 INFO Experiment: load system:exp:winlib
 INFO Experiment: load system:exp:stat
 INFO property.nodes: nodes = "system:topo:all" (String)
 INFO property.summary: summary = false (FalseClass)
 INFO Topology: Loaded topology 'system:topo:all'.

Talking to the CMC service, please wait
-----------------------------------------------
 Node: node1-1.sb1.orbit-lab.org   	 State: POWEROFF
 Node: node1-2.sb1.orbit-lab.org   	 State: POWEROFF
-----------------------------------------------

 INFO EXPERIMENT_DONE: Event triggered. Starting the associated tasks.
 INFO NodeHandler: 
 INFO NodeHandler: Shutting down experiment, please wait...
 INFO NodeHandler: 
 INFO run: Experiment default_slice-2015-08-19t14.54.21.510-04.00 finished after 0:5

Else power them off with

omf tell -a offh -t all

Next image node1-1 with the OpenAirInterface? trunk image

Dlambros@console.sb1:~$ omf load -i oai-trunk-new.ndz -t node1-1 -o 230

 INFO NodeHandler: OMF Experiment Controller 5.4 (git 5dd7e2c)
 INFO NodeHandler: Reading configuration file /etc/omf-expctl-5.4/services.yaml
 INFO NodeHandler: Add domain http - http://internal1.orbit-lab.org:5054/
 INFO NodeHandler: Add domain http - http://repository1.orbit-lab.org:5054/
 INFO NodeHandler: Add domain http - http://external1.orbit-lab.org:5054/
 INFO NodeHandler: Slice ID: pxe_slice 
 INFO NodeHandler: Experiment ID: pxe_slice-2015-08-19t14.56.22.769-04.00
 INFO NodeHandler: Message authentication is disabled
 INFO Experiment: load system:exp:stdlib
 INFO property.resetDelay: resetDelay = 230 (Fixnum)
 INFO property.resetTries: resetTries = 1 (Fixnum)
 INFO Experiment: load system:exp:eventlib
 INFO Experiment: load system:exp:winlib
 INFO Experiment: load system:exp:imageNode
 INFO property.nodes: nodes = "node1-1" (String)
 INFO property.image: image = "oai-trunk-new.ndz" (String)
 INFO property.domain: domain = "sb1.orbit-lab.org" (String)
 INFO property.outpath: outpath = "/tmp" (String)
 INFO property.outprefix: outprefix = "pxe_slice-2015-08-19t14.56.22.769-04.00" (String)
 INFO property.timeout: timeout = 230 (Fixnum)
 INFO property.resize: resize = nil (NilClass)
 INFO Topology: Loaded topology 'system:topo:registered'.
 INFO property.resetDelay: resetDelay = 200 (Fixnum)
 INFO Experiment: Resetting resources
 INFO stdlib: Waiting for nodes (Up/Down/Total): 0/1/1 - (still down: node1-1.sb1.orbit-lab.org) [0 sec.]
 INFO stdlib: Waiting for nodes (Up/Down/Total): 0/1/1 - (still down: node1-1.sb1.orbit-lab.org) [10 sec.]
 INFO stdlib: Waiting for nodes (Up/Down/Total): 0/1/1 - (still down: node1-1.sb1.orbit-lab.org) [20 sec.]
 INFO stdlib: Waiting for nodes (Up/Down/Total): 0/1/1 - (still down: node1-1.sb1.orbit-lab.org) [30 sec.]
 INFO stdlib: Waiting for nodes (Up/Down/Total): 0/1/1 - (still down: node1-1.sb1.orbit-lab.org) [40 sec.]
 INFO exp: Progress(0/0/1): 0/0/0 min(node1-1.sb1.orbit-lab.org)/avg/max (47) - Timeout: 220 sec.
 INFO ALL_UP: Event triggered. Starting the associated tasks.
 INFO exp: Progress(0/0/1): 20/20/20 min(node1-1.sb1.orbit-lab.org)/avg/max (47) - Timeout: 210 sec.
 INFO exp: Progress(0/0/1): 30/30/30 min(node1-1.sb1.orbit-lab.org)/avg/max (47) - Timeout: 200 sec.
 INFO exp: Progress(0/0/1): 60/60/60 min(node1-1.sb1.orbit-lab.org)/avg/max (47) - Timeout: 190 sec.
 INFO exp: Progress(0/0/1): 80/80/80 min(node1-1.sb1.orbit-lab.org)/avg/max (47) - Timeout: 180 sec.
 INFO exp: Progress(1/0/1): 100/100/100 min()/avg/max (47) - Timeout: 170 sec.
 INFO exp:  ----------------------------- 
 INFO exp:  Imaging Process Done 
 INFO exp:  1 node successfully imaged - Topology saved in '/tmp/pxe_slice-2015-08-19t14.56.22.769-04.00-topo-success.rb'
 INFO exp:  ----------------------------- 
 INFO EXPERIMENT_DONE: Event triggered. Starting the associated tasks.
 INFO NodeHandler: 
 INFO NodeHandler: Shutting down experiment, please wait...
 INFO NodeHandler: 
 INFO NodeHandler: Shutdown flag is set - Turning Off the resources
 INFO run: Experiment pxe_slice-2015-08-19t14.56.22.769-04.00 finished after 1:51

Then image node1-2 with the following

Dlambros@console.sb1:~$ omf load -i ubuntu-14-04-64bit-sdr-full.ndz -t node1-2 -o 230

 INFO NodeHandler: OMF Experiment Controller 5.4 (git 5dd7e2c)
 INFO NodeHandler: Reading configuration file /etc/omf-expctl-5.4/services.yaml
 INFO NodeHandler: Add domain http - http://internal1.orbit-lab.org:5054/
 INFO NodeHandler: Add domain http - http://repository1.orbit-lab.org:5054/
 INFO NodeHandler: Add domain http - http://external1.orbit-lab.org:5054/
 INFO NodeHandler: Slice ID: pxe_slice 
 INFO NodeHandler: Experiment ID: pxe_slice-2015-08-19t14.59.39.330-04.00
 INFO NodeHandler: Message authentication is disabled
 INFO Experiment: load system:exp:stdlib
 INFO property.resetDelay: resetDelay = 230 (Fixnum)
 INFO property.resetTries: resetTries = 1 (Fixnum)
 INFO Experiment: load system:exp:eventlib
 INFO Experiment: load system:exp:winlib
 INFO Experiment: load system:exp:imageNode
 INFO property.nodes: nodes = "node1-2" (String)
 INFO property.image: image = "ubuntu-14-04-64bit-sdr-full.ndz" (String)
 INFO property.domain: domain = "sb1.orbit-lab.org" (String)
 INFO property.outpath: outpath = "/tmp" (String)
 INFO property.outprefix: outprefix = "pxe_slice-2015-08-19t14.59.39.330-04.00" (String)
 INFO property.timeout: timeout = 230 (Fixnum)
 INFO property.resize: resize = nil (NilClass)
 INFO Topology: Loaded topology 'system:topo:registered'.
 INFO property.resetDelay: resetDelay = 200 (Fixnum)
 INFO Experiment: Resetting resources
 INFO stdlib: Waiting for nodes (Up/Down/Total): 0/1/1 - (still down: node1-2.sb1.orbit-lab.org) [0 sec.]
 INFO stdlib: Waiting for nodes (Up/Down/Total): 0/1/1 - (still down: node1-2.sb1.orbit-lab.org) [10 sec.]
 INFO stdlib: Waiting for nodes (Up/Down/Total): 0/1/1 - (still down: node1-2.sb1.orbit-lab.org) [20 sec.]
 INFO stdlib: Waiting for nodes (Up/Down/Total): 0/1/1 - (still down: node1-2.sb1.orbit-lab.org) [30 sec.]
 INFO stdlib: Waiting for nodes (Up/Down/Total): 0/1/1 - (still down: node1-2.sb1.orbit-lab.org) [40 sec.]
 INFO exp: Progress(0/0/1): 0/0/0 min(node1-2.sb1.orbit-lab.org)/avg/max (46) - Timeout: 220 sec.
 INFO ALL_UP: Event triggered. Starting the associated tasks.
 INFO exp: Progress(0/0/1): 20/20/20 min(node1-2.sb1.orbit-lab.org)/avg/max (46) - Timeout: 210 sec.
 INFO exp: Progress(0/0/1): 30/30/30 min(node1-2.sb1.orbit-lab.org)/avg/max (46) - Timeout: 200 sec.
 INFO exp: Progress(0/0/1): 50/50/50 min(node1-2.sb1.orbit-lab.org)/avg/max (46) - Timeout: 190 sec.
 INFO exp: Progress(0/0/1): 60/60/60 min(node1-2.sb1.orbit-lab.org)/avg/max (46) - Timeout: 180 sec.
 INFO exp: Progress(0/0/1): 70/70/70 min(node1-2.sb1.orbit-lab.org)/avg/max (46) - Timeout: 170 sec.
 INFO exp: Progress(0/0/1): 90/90/90 min(node1-2.sb1.orbit-lab.org)/avg/max (46) - Timeout: 160 sec.
 INFO exp: Progress(1/0/1): 100/100/100 min()/avg/max (46) - Timeout: 150 sec.
 INFO exp:  ----------------------------- 
 INFO exp:  Imaging Process Done 
 INFO exp:  1 node successfully imaged - Topology saved in '/tmp/pxe_slice-2015-08-19t14.59.39.330-04.00-topo-success.rb'
 INFO exp:  ----------------------------- 
 INFO EXPERIMENT_DONE: Event triggered. Starting the associated tasks.
 INFO NodeHandler: 
 INFO NodeHandler: Shutting down experiment, please wait...
 INFO NodeHandler: 
 INFO NodeHandler: Shutdown flag is set - Turning Off the resources
 INFO run: Experiment pxe_slice-2015-08-19t14.59.39.330-04.00 finished after 2:11

http://www.orbit-lab.org/raw-attachment/wiki/Other/Summer/2015/aSDR3/TDD_IQ_1.4MHz.png http://www.orbit-lab.org/raw-attachment/wiki/Other/Summer/2015/aSDR3/TDD_IQ_5MHz.png
http://www.orbit-lab.org/raw-attachment/wiki/Other/Summer/2015/aSDR3/TDD_IQ_10MHz.png http://www.orbit-lab.org/raw-attachment/wiki/Other/Summer/2015/aSDR3/TDD_IQ_20MHz.png

Experiment 7: TDD Waterfall Plot

http://www.orbit-lab.org/raw-attachment/wiki/Other/Summer/2015/aSDR3/TDD_LTE_QT_WF.png

Poster

http://www.orbit-lab.org/raw-attachment/wiki/Other/Summer/2015/aSDR3/WINLAB Poster.jpg

Members

Cat Le
Electrical and Computer Engineering
Rutgers University
Demetrios Lambropoulos
Electrical and Computer Engineering
Rutgers University
Steven Cheng
Computer Science
Rutgers University

*Led by Dola Saha and Ivan Seskar

Materials

Presentation: Week 1

Presentation: Week 2

Presentation: Week 3

Presentation: Week 4

Presentation: Week 5

Presentation: Week 6

Presentation: Week 7 OpenAirInterface

Presentation: Week 8

Presentation: Week 9

Presentation: Week 10

Presentation: Week 11

Presentation: Week 12 OpenAir1 OpenAir2

Resources

LTE Unlicensed Augmenting Mobile Data Capacity But Coexistence Needs Consideration

U-LTE: Unlicensed Spectrum Utilization of LTE

Extending LTE Advanced to Unlicensed Spectrum

The Prospect Of LTE And Wi-Fi Sharing Unlicensed Spectrum

Coexistence of LTE and WiFi Heterogeneous Networks via Inter Network Coordination

Last modified 2 years ago Last modified on 09/02/15 12:34:08

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