Skip to main content Accessibility help
×
Hostname: page-component-7c8c6479df-995ml Total loading time: 0 Render date: 2024-03-19T11:30:25.845Z Has data issue: false hasContentIssue false

13 - Power control

Published online by Cambridge University Press:  28 February 2011

Farooq Khan
Affiliation:
Samsung Telecommunications America, Richardson, Texas
Get access

Summary

The goal of power control is to transmit at the right amount of power needed to support a certain data rate. Too much power generates unnecessary interference, while too little power results in an increased error rate requiring retransmissions and hence resulting in larger transmission delays and lower throughputs. In a WCDMA system, power control is important particularly in the uplink to avoid the near–far problem. This is because the uplink transmissions are nonorthogonal and very high signal levels from cell-center UEs can overwhelm the weak signals received from cell-edge UEs. Therefore, a very elaborate power control mechanism based on the fast closed-loop principle is used in the WCDMA system. Similarly, power control is used for the downlink of WCDMA systems to support the fixed rate delay-sensitive voice service. However, for high-speed data transmission in WCDMA/HSPA systems, transmissions are generally performed at full power and link adaptation is preferably used to match the data rate to the channel conditions.

The LTE uplink uses orthogonal SC-FDMA access and hence the near–far problem of WCDMA does not exist. However, high levels of interference from neighboring cells can still limit the uplink coverage if UEs in the neighboring cells are not power controlled. The cellular systems are generally coverage limited in the uplink due to limited UE transmit power. The increased levels of interference from neighboring cells increase Interference over Thermal (IoT) limiting coverage at the desired cell. Therefore, uplink power control is beneficial in an orthogonal uplink access as well.

Type
Chapter
Information
LTE for 4G Mobile Broadband
Air Interface Technologies and Performance
, pp. 329 - 341
Publisher: Cambridge University Press
Print publication year: 2009

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

Save book to Kindle

To save this book to your Kindle, first ensure coreplatform@cambridge.org is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part of your Kindle email address below. Find out more about saving to your Kindle.

Note you can select to save to either the @free.kindle.com or @kindle.com variations. ‘@free.kindle.com’ emails are free but can only be saved to your device when it is connected to wi-fi. ‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.

Find out more about the Kindle Personal Document Service.

  • Power control
  • Farooq Khan
  • Book: LTE for 4G Mobile Broadband
  • Online publication: 28 February 2011
  • Chapter DOI: https://doi.org/10.1017/CBO9780511810336.014
Available formats
×

Save book to Dropbox

To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Dropbox.

  • Power control
  • Farooq Khan
  • Book: LTE for 4G Mobile Broadband
  • Online publication: 28 February 2011
  • Chapter DOI: https://doi.org/10.1017/CBO9780511810336.014
Available formats
×

Save book to Google Drive

To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Google Drive.

  • Power control
  • Farooq Khan
  • Book: LTE for 4G Mobile Broadband
  • Online publication: 28 February 2011
  • Chapter DOI: https://doi.org/10.1017/CBO9780511810336.014
Available formats
×