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What is the difference in operations of DRX in connected mode and DRX in IDle mode?

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What is the difference in operations of DRX in connected mode and DRX in IDle mode?
posted May 16, 2014 by Nikhil Pandey

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UE shouldn't remain asleep in idle mode. If any downlink data comes , it should be paged. So UE is given (chosen by itself or configured by eNB) occasion to wake up & receive the message .
In Connected state also , he may remain inactive for some time as there
might not be any data to send & receive but still UE keeps monitoring PDCCH , that consumes battery henceforth ue is configured with C-Drx so he can listen to pdcch Discontinuously so as to save battery power.
commented May 16, 2014 by anonymous

1 Answer

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In RRC idle mode the UE only needs to wake up every paging period to check if there are incoming paging for the UE (as well as possible modification of system information/ETWS/CMAS transmission). In addition, for mobility purposes the UE needs to perform certain measurements (such as serving cell RSRP, possibly also RSRQ, and neighbour measurements depending on serving cell radio signal strength /quality as well as network configured parameters).

In RRC connected mode, the usage of DRX is somewhat different and opportunistic (if DRX is configured and there is no data to be sent or received, the UE can enter specified inactivity period) in a sense.

If you want to go in more deep. Read below links:

http://lteuniversity.com/get_trained/expert_opinion1/b/prakash/archive/2013/04/17/discontinuous-reception-drx-in-rrc-idle-part-1.aspx

http://allabtlte.blogspot.in/2014/01/all-about-discontinuous-reception-drx.html

http://www.telecomfunda.com/2014/05/discontinuous-reception-drx-in-rrc_idle/

answer May 19, 2014 by Hiteshwar Thakur
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During my study about the measurement and ANR, I have the question. Please help to let me get the proper answer.
[ Condition]
1. UE is in the connected state.
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3. eNB sends rrcConnectionReconfigurationMessage to read CGI for that PCI.
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In Step 4), In some materials on the web, UE should use IDLE periods to get SIB1, which is configured as DRX config in rrcConectionReconfigurationMesage. Because Measurement Gap is too short to read MIB/SIB1 and it's only for the measurement purpose.

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When UE is in the Connected State, How UE could use DRX configuration which is intended to use in IDLE state?

As my basic understanding, DRX configuration is to improve the battery life in idle mode.

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