https://urgentcomm.com/wp-content/themes/ucm_child/assets/images/logo/footer-new-logo.png
  • Home
  • News
  • Multimedia
    • Back
    • Multimedia
    • Video
    • Podcasts
    • Galleries
  • Commentary
    • Back
    • Commentary
    • Urgent Matters
    • View From The Top
    • All Things IWCE
    • Legal Matters
  • Resources
    • Back
    • Resources
    • Webinars
    • White Papers
    • Reprints & Reuse
  • IWCE
    • Back
    • IWCE
    • Conference
    • Special Events
    • Exhibitor Listings
    • Premier Partners
    • Floor Plan
    • Exhibiting Information
    • Register for IWCE
  • About Us
    • Back
    • About Us
    • Contact Us
    • Advertise
    • Terms of Service
    • Privacy Statement
    • Cookies Policy
  • Related Sites
    • Back
    • American City & County
    • IWCE
    • Light Reading
    • IOT World Today
    • Mission Critical Technologies
    • Microwave/RF
    • T&D World
    • TU-Auto
  • In the field
    • Back
    • In the field
    • Broadband Push-to-X
    • Internet of Things
    • Project 25
    • Public-Safety Broadband/FirstNet
    • Virtual/Augmented Reality
    • Land Mobile Radio
    • Long Term Evolution (LTE)
    • Applications
    • Drones/Robots
    • IoT/Smart X
    • Software
    • Subscriber Devices
    • Video
  • Call Center/Command
    • Back
    • Call Center/Command
    • Artificial Intelligence
    • NG911
    • Alerting Systems
    • Analytics
    • Dispatch/Call-taking
    • Incident Command/Situational Awareness
    • Tracking, Monitoring & Control
  • Network Tech
    • Back
    • Network Tech
    • Interoperability
    • LMR 100
    • LMR 200
    • Backhaul
    • Deployables
    • Power
    • Tower & Site
    • Wireless Networks
    • Coverage/Interference
    • Security
    • System Design
    • System Installation
    • System Operation
    • Test & Measurement
  • Operations
    • Back
    • Operations
    • Critical Infrastructure
    • Enterprise
    • Federal Government/Military
    • Public Safety
    • State & Local Government
    • Training
  • Regulations
    • Back
    • Regulations
    • Narrowbanding
    • T-Band
    • Rebanding
    • TV White Spaces
    • None
    • Funding
    • Policy
    • Regional Coordination
    • Standards
  • Organizations
    • Back
    • Organizations
    • AASHTO
    • APCO
    • DHS
    • DMR Association
    • ETA
    • EWA
    • FCC
    • IWCE
    • NASEMSO
    • NATE
    • NXDN Forum
    • NENA
    • NIST/PSCR
    • NPSTC
    • NTIA/FirstNet
    • P25 TIG
    • TETRA + CCA
    • UTC
Urgent Communications
  • NEWSLETTER
  • Home
  • News
  • Multimedia
    • Back
    • Video
    • Podcasts
    • Omdia Crit Comms Circle Podcast
    • Galleries
    • IWCE’s Video Showcase
  • Commentary
    • Back
    • All Things IWCE
    • Urgent Matters
    • View From The Top
    • Legal Matters
  • Resources
    • Back
    • Webinars
    • White Papers
    • Reprints & Reuse
    • UC eZines
    • Sponsored content
  • IWCE
    • Back
    • Conference
    • Why Attend
    • Exhibitor Listing
    • Floor Plan
    • Exhibiting Information
    • Join the Event Mailing List
  • About Us
    • Back
    • About Us
    • Contact Us
    • Advertise
    • Terms of Service
    • Privacy Statement
    • Cookies Policy
  • Related Sites
    • Back
    • American City & County
    • IWCE
    • Light Reading
    • IOT World Today
    • TU-Auto
  • newsletter
  • In the field
    • Back
    • Internet of Things
    • Broadband Push-to-X
    • Project 25
    • Public-Safety Broadband/FirstNet
    • Virtual/Augmented Reality
    • Land Mobile Radio
    • Long Term Evolution (LTE)
    • Applications
    • Drones/Robots
    • IoT/Smart X
    • Software
    • Subscriber Devices
    • Video
  • Call Center/Command
    • Back
    • Artificial Intelligence
    • NG911
    • Alerting Systems
    • Analytics
    • Dispatch/Call-taking
    • Incident Command/Situational Awareness
    • Tracking, Monitoring & Control
  • Network Tech
    • Back
    • Cybersecurity
    • Interoperability
    • LMR 100
    • LMR 200
    • Backhaul
    • Deployables
    • Power
    • Tower & Site
    • Wireless Networks
    • Coverage/Interference
    • Security
    • System Design
    • System Installation
    • System Operation
    • Test & Measurement
  • Operations
    • Back
    • Critical Infrastructure
    • Enterprise
    • Federal Government/Military
    • Public Safety
    • State & Local Government
    • Training
  • Regulations
    • Back
    • Narrowbanding
    • T-Band
    • Rebanding
    • TV White Spaces
    • None
    • Funding
    • Policy
    • Regional Coordination
    • Standards
  • Organizations
    • Back
    • AASHTO
    • APCO
    • DHS
    • DMR Association
    • ETA
    • EWA
    • FCC
    • IWCE
    • NASEMSO
    • NATE
    • NXDN Forum
    • NENA
    • NIST/PSCR
    • NPSTC
    • NTIA/FirstNet
    • P25 TIG
    • TETRA + CCA
    • UTC
acc.com

Uplink considerations

Uplink considerations

  • Written by raidee
  • 1st October 2018

Uplink receiver noise floor. For both LTE ENodeB or LMR base stations, the uplink (talkback) receiver is in a fixed environment for mobile data systems. Similar to the downlink case, the uplink receiver must distinguish between wanted and unwanted signals, so the thermal noise floor and effective receiver sensitivity must be estimated using Boltzmann’s constant. ENBW for LMR systems is the same for uplink and downlink, 6000 Hz. LTE can deliver additional resource blocks—in this case, 4 resource blocks—in the uplink to provide data speeds of 756 kb/s at the cell edge, and has an ENBW of 720 kHz. LMR systems use QPSK to deliver 12 kb/s throughout the area of the cell, also about 1 bit/second/hertz.

Assuming a noise figure of 2.5 dB for the LTE receiver, an ENodeB radio at the base-station sites, and a noise figure of 2.5 dB for the LMR receiver at the base-station sites, Boltzmann’s constant yields about -131 dBm for narrowband LMR channels and -127 dBm for the broadband channel. This again establishes the noise floor for both technologies in the uplink with a 4 dB advantage for LMR.

Uplink effective receiver sensitivity. The next step to calculate the effective receiver sensitivity of the uplink is to determine the minimum useable signal above the noise floor. With a minimal delivered data rate of 768 kb/s and using MS-4, LTE’s required SINR value is 0 dB plus a 11.5 dB Raleigh fast fade margin—or 11.5 dB. There is also a handoff gain of 2.8 dB and a fixed IoT gain of 3 dB for the LTE uplink.

For LMR systems with no tower-top amplifier or receiver multicoupler, a typical uplink value of faded C/(I+N), for a digital audio quality value of 3.4, is 17.7 dB. For LMR data transmissions of 12 kb/s, a typical faded C/(I+N) is 18 dB. The effective receive design value, or RSRP design threshold, for LTE broadband is -109 dBm, while the effective receiver design for LMR is -113 dBm—a 4 dB difference in favor of LMR systems.

Uplink transmission considerations. As with the downlink, the transmission to an LTE subscriber device with a 10 MHz bandwidth does not compare “apples to apples” with narrowband LMR transmissions of 12.5 kHz. At the subscriber device, LTE delivers data rates of 768 kb/s per user; for LMR systems, the bandwidth is 12 kb/s. Transmission power for LTE and LMR modem subscriber devices is 23 dBm, with a -4 dB antenna, for an ERP of 19 dBm.

Uplink antenna systems. LTE antenna systems utilize 12 dBd MIMO panel antennas and are sectorized, while LMR antennas are omnidirectional and have a gain of 9 dBd. LTE antenna systems in the uplink are 6 dB stronger than LMR systems, assuming the frequency bands are both 700 MHz and the transmission lines and filtering for LTE are 3 dB less than LMR. Uplink filtering losses and transmission lines are minimal for LTE when collocated with the transmitter, while the LMR transmission lines reach to the radio base station shelters and the losses are higher. Filter losses for LMR in the uplink are higher to allow for close narrowbanded channel separations.

Uplink maximum available path loss.To determine the uplink MAPL for LMR, start with a subscriber device transmitting 19 dBm ERP. Assuming the uplink LMR receiver is a radio base station with a 9 dB gain antenna, 2 dB transmission line losses and an effective receiver design level of -113 dBm, the MAPL is 139 dB. For LTE, the uplink MAPL is 19 dBm for the transmitter ERP and a base station ENodeB receiver antenna of 12 dBd, and an effective receiver design level of -109 dBm, with 6 dB for the fixed IoT and handoff factors—add it all up and the MAPL is 134 dBm. The difference is a 5 dB signal strength advantage for LMR.

Thus, the downlink MAPL for LTE is 127 dB and the downlink MAPL for LMR is 156 dB. The uplink MAPL for LTE is 134 dB and the uplink MAPL for LMR is 139 dB. So, the links for LTE are imbalanced by 7 dB downlink limited and for LMR are imbalanced by 15 dB uplink limited.

The next step is to attempt to balance these links. For LTE, with a downlink imbalance, one approach theoretically would be to increase the ENodeB transmitter power, but that would require 3GPP to develop better cell-edge interference mitigation techniques. With an LMR uplink imbalance, the best approach is to lower the base station transmitter power or add low-noise amplification before the base-station receiver.

The next article in the series applies these link-budget techniques to an RF planning tool to consider the uplink and downlink differences and the differences between predicted LTE and LMR coverage. With a downlink disadvantage of 29 dB, LTE coverage will be much less than LMR from the same site, even before the lower heights of LTE antennas are considered. With an uplink disadvantage of 5 dB, LTE coverage also will be less than LMR, but not as bad as in the downlink. 

Robert C. Shapiro, P.E., is a consulting engineer who has been in land mobile radio engineering—including public-safety and transportation communications—since 1984. He serves on the TIA TR8 committee (TSB-88) as vice chair and is a senior member of the IEEE. He can be reached at [email protected]

Tags:

Related Content

  • RapidSOS hires Parkinson to head public-sector efforts
  • Verizon Robotics to test drones at Oregon's Pendleton Range
  • Cyber conflict overshadowed a major government ransomware alert
  • Former Dem senator launches campaign to squash Gigi Sohn's FCC confirmation

Commentary


LTE and liability: Why the fire service must move forward with digital incident command

  • 2
6th May 2022

Partnership and collaboration must be the foundation for emergency communications

18th April 2022

FirstNet success means no hypothetical ‘shots’ need to be fired, Swenson says

22nd February 2022
view all

Events


UC Ezines


IWCE 2019 Wrap Up

13th May 2019
view all

Twitter


UrgentComm

Newscan: Japanese carrier outage lasts multiple days dlvr.it/STS9JJ

6th July 2022
UrgentComm

Criminals use deepfake videos to interview for remote work dlvr.it/STRjZM

6th July 2022
UrgentComm

Tesla recalls 59,000 vehicles over emergency-call software glitch dlvr.it/STRcgT

6th July 2022
UrgentComm

Report: Reforming emergency dispatch won’t be easy, but it’s necessary dlvr.it/STRYNP

6th July 2022
UrgentComm

FCC clears SpaceX to connect Starlink to boats, planes, other moving vehicles dlvr.it/STRXGB

6th July 2022
UrgentComm

Judge orders Hytera to make large royalty payment this month to Motorola Solutions dlvr.it/STRRQc

6th July 2022
UrgentComm

Sesame Solar leverages mobile solar, hydrogen to power efforts beyond the grid dlvr.it/ST8m3K

1st July 2022
UrgentComm

Newscan: On front lines, communications breakdowns prove costly for Ukraine dlvr.it/ST7fnC

30th June 2022

Newsletter

Sign up for UrgentComm’s newsletters to receive regular news and information updates about Communications and Technology.

Expert Commentary

Learn from experts about the latest technology in automation, machine-learning, big data and cybersecurity.

Business Media

Find the latest videos and media from the market leaders.

Media Kit and Advertising

Want to reach our digital and print audiences? Learn more here.

DISCOVER MORE FROM INFORMA TECH

  • American City & County
  • IWCE
  • Light Reading
  • IOT World Today
  • Mission Critical Technologies
  • Microwave/RF
  • T&D World
  • TU-Auto

WORKING WITH US

  • About Us
  • Contact Us
  • Events
  • Careers

FOLLOW Urgent Comms ON SOCIAL

  • Privacy
  • CCPA: “Do Not Sell My Data”
  • Cookies Policy
  • Terms
Copyright © 2022 Informa PLC. Informa PLC is registered in England and Wales with company number 8860726 whose registered and Head office is 5 Howick Place, London, SW1P 1WG.
This website uses cookies, including third party ones, to allow for analysis of how people use our website in order to improve your experience and our services. By continuing to use our website, you agree to the use of such cookies. Click here for more information on our Cookie Policy and Privacy Policy.
X