NR Bandwidth part (BWP) Concept


NR Bandwidth Part Concept :

NR system supports much wider maximum CBW than LTE’s 20 MHz whereas In LTE in order to achieve wider bandwidth that can be done through Carrier Aggregation( CA) by adding extra Carriers (CC’s) .
         
So , what is the use of Wider BW ?
            Answer is Wider bw will help to achieve higher data rates
         Does UE really required wider BW always ?
   Answer is UE doesn't always required to have high date rates , so the use of wide bw may imply power consumption in both RF and base band signal processing perspectives.

New concept is designed in NR i.e. Band width part (BWP) and it addresses all issues as I mentioned above  - BWP concept in NR helps UE to access small BW than configured CBW which make NR energy efficient solution despite of having of wideband support
This way UE can be configured different bandwidth parts out of those at a time UE can access only one BWP and that will be Chosen by network and subsequently it will activate that specific BWP to UE  , so that UE can consider to be schedule to transmit and receive in certain freq range which mean only UE can do operations of TX/Rx only in active BandWidth Part

BWP - is formed of some set of contiguous Rb's and that is signaled to UE via RRC signaling

·         The BW of a BWP cannot exceed the configured CC BW for the UE
·         BW of the BWP must be at least as large as one SS block BW ,  but the BWP may or may not contain SS block
·         Each BWP is associated with a specific numerology, i.e., SCS and CP type.
·         And network can configure multiple BWP to UE via RRC signaling and it may overlap in frequency's
·         And the granularity of is one PRB (atleast)
·         DL and UL BWP's are configured separately and independently for paired spectrum (FDD) and up to four BWPs can be configured for DL and UL each 
·         For unpaired spectrum(TDD), a DL BWP and a UL BWP are jointly configured as a pair and up to 4 pairs can be configured

=> UE's are expected to send and receive in defined frequency of active BWp's only

Each BWP will have one control resource Set (CORE SET ) and UE search space (USS) - USS Is used to monitor possible control information destined for the UE
Whereas in PRIMARY CARRIER at least one of the BWP will have one coreset with Common search space (CSS) - CSS is to monitor control information send my network to all UE's or destined to particular UE
Incase if active BWP Coreset is not configured with CSS then UE is not required to monitor


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