Received signal strength indicator: Difference between revisions

Revision as of 10:54, 17 March 2025

Latest revision as of 05:07, 26 May 2025

(One intermediate revision by one other user not shown)

Line 15:

There is no standardized relationship of any particular physical parameter to the RSSI reading. The 802.11 standard does not define any relationship between RSSI value and power level in [[milliwatts]] or [[dBm|decibels referenced to one milliwatt (dBm)]]. Vendors and chipset makers provide their own accuracy, granularity, and range for the actual power (measured as milliwatts, which can be expressed in terms of decibels relative to one milliwatt) and their range of RSSI values (from 0 to RSSI maximum, in arbitrary signal units "asu").<ref>{{cite conference|last1=Lui|first1=Gough|last2=Gallagher|first2=Thomas|last3=Binghao|first3=Li|conference=2011 International Conference on Localization and GNSS (ICL-GNSS)|title=Differences in RSSI readings made by different Wi-Fi chipsets: A limitation of WLAN localization|pages=53–57|doi=10.1109/ICL-GNSS.2011.5955283|isbn=978-1-4577-0186-3|year=2011|s2cid=16846238|hdl=1959.4/unsworks_47285|hdl-access=free}}</ref> One subtlety of the 802.11 RSSI metric comes from how it is sampled{{mdash}}RSSI is acquired during only the preamble stage of receiving an 802.11 frame, not over the full frame.<ref name=":0" />

As early as 2000, researchers were able to use RSSI for coarse-grained ___location estimates.<ref name=bahl-infocom2000>{{cite conference|last1=Paramvir|first1=Bahl|last2=Padmanabhan|first2=Venkata|title=RADAR: An In-Building RF-based User Location and Tracking System|url=https://www.microsoft.com/en-us/research/publication/radar-an-in-building-rf-based-user-___location-and-tracking-system/|book-title=Proceedings IEEE INFOCOM 2000. Conference on Computer Communications. Nineteenth Annual Joint Conference of the IEEE Computer and Communications Societies|doi=10.1109/INFCOM.2000.832252|access-date=19 December 2014|url-access=subscription}}</ref> More recent work was able to reproduce these results using more advanced techniques.<ref name="sev-mobisys2013">{{cite conference|last1 = Sen|first1 = Souvik|last2 = Lee|first2 = Jeongkeun|last3 = Kim|first3 = Kyu-Han|last4 = Congdon|first4 = Paul|title = Avoiding Multipath to Revive Inbuilding WiFi Localization|url = http://dl.acm.org/citation.cfm?id=2464463|book-title = MobiSys '13: Proceeding of the 11th annual international conference on Mobile systems, applications, and services | year=2013 | pages=249–262 | doi=10.1145/2462456.2464463 | isbn=9781450316729 | s2cid=16251944 |accessdate = 19 December 2014|url-access = subscription}}</ref> Nevertheless, RSSI does not always provide measurements that are sufficiently accurate to properly determine the ___location.<ref name=parameswaran-srds2009>{{cite conference |last1=Parameswaran |first1=Ambili Thottam |last2=Husain |first2=Mohammad Iftekhar |last3=Upadhyaya |first3=Shambhu |title=Is RSSI a Reliable Parameter in Sensor Localization Algorithms – An Experimental Study |url=http://www.cse.buffalo.edu/srds2009/F2DA/f2da09_RSSI_Parameswaran.pdf |date=27 September 2009 |___location=Niagara Falls, New York |conference=28th IEEE Symposium On Reliable Distributed Systems |conference-url=https://cse.buffalo.edu/srds2009/ |access-date=12 March 2025}}</ref> However, RSSI still represents the most feasible indicator for localization purposes as it is available in almost all wireless nodes and it does not have any additional hardware requirements.<ref name=abdullah2016>{{cite journal|url=https://www.researchgate.net/publication/309257981 |last1=Alhasanat|first1=Abdullah|last2=Sharif|first2= Bayan |last3= Tsemendis|first3= C. |title=Efficient RSS-based collaborative localisation in wireless sensor networks|date=January 2016 |journal=International Journal of Sensor Networks |volume=22 |issue=1 |pages=27–36 |doi=10.1504/IJSNET.2016.079335}}</ref>

=== Received channel power indicator ===

For the most part, 802.11 RSSI has been replaced with ''received channel power indicator'' [[Received_Channel_Power_Indicator|(''RCPI''). RCPI]] is an 802.11<ref name=":0">{{cite web|url=http://standards.ieee.org/getieee802/802.11.html |archive-url=https://archive.today/20100813230349/http://standards.ieee.org/getieee802/802.11.html |url-status=dead |archive-date=August 13, 2010 |title=IEEE 802.11-2012 |publisher=IEEE |date=2012-03-29 |accessdate=2013-02-11}}</ref> measure of the received [[radio frequency]] [[Power (physics)|power]] in a selected [[Channel (communications)|channel]] over the preamble ''and'' the entire received [[Frame (telecommunications)|frame]], and has defined absolute levels of accuracy and resolution. RCPI is exclusively associated with [[802.11]] and as such has some accuracy and resolution enforced on it through [[IEEE 802.11k-2008]]. Received signal power level assessment is a necessary step in establishing a link for communication between wireless nodes. However, a power level metric like RCPI generally cannot comment on the ''quality'' of the link like other metrics such as travel time measurement ([[time of arrival]]).

== Uses in indoor localization ==