LTE ISI (INTER SYMBOL INTERFERENCE)

LTE INTER SYMBOL INTERFERENCE

When Interference occurs between two symbols because of straight path and reflected path it’s called ISI.

ISI STRAIGHT VS REFLECTED WAVE:

ISI SOLUTIONS:

** ISI OLD SOLUTIONS:

(1) Rake Receiver:

It’s a Multi Finger antenna which is capable for receiving and separating multi directional waves.

Advantages:

·         No ISI any more.

·         Due to Multipath reception diversity increases the signal decoding success rate.

Disadvantage:

·         Expensive due to use of Rake receiver

·         High Power consumption required for multi signal processing.

(2) ISI FACTORS

·         Delay Time: If delay time increase than ISI will increase and vice versa.

·         Bandwidth: If Bandwidth increase than ISI will increase and vice versa.

** ISI NEW SOLUTIONS:

(1) Sub Carrier Techniques:

In this techniques each sub-carrier size should be 15 kHz Bandwidth because if lower the bandwidth so ISI also less.

LTE Sub-carrier: Scalable Bandwidth in below table:

 LTE Cyclic Prefix Method:

Add a waste piece at a start of a symbol so that it can absorb the shock of the impact.

·         Short CP: 14000 symbols per second per sub carrier and remaining 1000 symbols are used as a cyclic prefix.

·         Long CP: 12000 Symbols per second per sub-carrier.

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LTE SAE EPS BEARERS

EPS BEARERS

EPS BEARERS:

·   EPS Bearer spans across LTE Network From UE to PGW

·   Every EPS Bearer created for a UE contains a ID for managing it across the network

·   Every EPS Bearer is associated with a Quality Of Service Class Identifier (QCI)

PDN AND APPLICATIONS:

·     Every UE May Contain Many EPS Bearers. Each EPS Bearer would contain a Different QoS Implementation!

·     Every UE which is ‘Attached’ to an LTE Network Must

–   At Least Be Connected To One ‘PDN’

–   For Every PDN UE Is Connected, It Must

o  Have '1' Default Bearer

o  '0' OR More Dedicated Bearers

• EPS BEARER PROPERTIES

• DEFAULT AND DEDICATED BEARER

·         GBR(Guarantee bit rate): Guarantee delivery of packets on high priority

·         NGBR(Non-GBR): No guaranteed delivery, priority can be late.

·         MBR(Maximum Bit rate): MBR is always greater than GBR.

·         QCI(Quality of Service class Identifier): Below Table for QCI.

·         ARP(Allocation Retention Priority): Used to set priority to reduce the congestion in the network.

·         AMBR(Aggregate MBR): Total data rate applicable for mobile phones in the particular PDN so AMBR is divided into multiple MBR.

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LTE INTERFACES WITH PROTOCOLS

LTE PROTOCOL INTRODUCTION

INTRODUCTION OF PROTOCOLS:

·   There are three broad categories of Protocols

o Application Protocols

o Processing Protocols

o Delivery Protocols

·   Application Protocols: Generate the Information required for the Communication of Nodes to achieve their Functionalities!

·   Processing Protocols: Process the Information generated by Application protocols!

·   Delivery Protocols: Send the Processed Information from Source to Destination!

COMPUTER COMMUNICATION PROTOCOLS

 This is work on a principle of OSI communication have 7 layer shown in below. This communication is done by the use of Switches and Router between two computers.

LTE MOBILE PROTOCOL LAYER

 Its work on Application, Delivery and Processing Protocols.      

LTE WIRELESS NETWORK INTERFACES

 There are many Interfaces in LTE network which are mentioned below:

LTE INTEFACES	PURPOSE
LTE-Uu	Interface between UE to Enb
X2	Interface between two adjacent eNBs
S1-MME	Interface between eNB to MME
S1-U	Interface between eNB to SGW
S3	Interface between MME to SGSN
S4	Interface between SGW to SGSN
S5/S8	Interface between SGW to PGW
S6a	Interface between MME to HSS
S6d	Interface between SGSN to HSS
S7/Gx	Interface between PGW to PCRF
S9	Interface between hPCRF to vPCRF
S10	Interface between MME to MME
S11	Interface between MME to SGW
S12	Interface between SGW to RNC
S13	Interface between MME to EIR
S13'	Interface between SGSN to EIR
S16	Interface between SGSN to SGSN
Gy	Interface between PGW to OFCS
Gz	Interface between PGW to OCS

Transport Protocols

 There are few Transport Protocol which we need to know before proceed to further:

·     TCP: Transmission control Protocol

o   It’s a connection oriented protocol.

o   It’s a reliable protocol.

o   It rearrange the data packet in the order specified.

o   Speed is slower than UDP because its attempt error recovery process also.

o   Header size is 20 Bytes

o   Guaranteed to data delivery.

·     UDP: User Datagram Protocol

o   It’s a connectionless protocol.

o   It’s not reliable protocol.

o   It is not rearrange the data packet in the order specified.

o   Speed is faster because its not attempt error recovery process.

o   Header size is 8 Bytes

o   No Guaranteed for data delivery.

·  GTP: GPRS Tunneling Protocol

o   Its used to encapsulate user data when passing through that core network.

o   It provide mobility when UE is in mobility state, the IP address remain same and packet are still forwarded since tunneling is provide between PGW and eNB via SGW.

o   There are two types GTPC is used for control plane and  GTPU is used for USER plane.

o   Main IP is hidden so provided security also.

·         SCTP: Stream Control Transmission protocol

o   It’s a connection oriented protocol.

o   It’s a reliable protocol.

o   It rearrange the data packet in the order specified.

o   It does bundling the message but TCP doesn’t.

o   Guaranteed to data delivery

·         Diameter: Its is a important protocol used for those components whose functionality come under AAA(Authentication, Authorization and Accounting) category. Its not a 3GPP protocol.

LTE WIRELESS NETWORK PROTOCOLS

 These are the main application and transport protocol used for LTE Network:

PROTOCOL SUMMARY

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LTE FUNDAMENTALS

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Paging in 5GNR

Paging for 5GS offerings:

• The network shall initiate the paging procedure for 5GS services or NAS signaling messages or user data is pending and need to be sent to the UE in 5GMM-IDLE mode
• The paging system is performed by 3GPP network and used for establishment of an NAS signaling connection with UE.
• The use of paging procedure is to request to the UE to re-establish the user plane resources of PDU sessions for down-link.
• Another use of the paging technique is to request the UE to re-setup the user-plane resources of PDU session(s) related to non-3GPP.
• Additionally, the network can use the paging system to provoke the cell terminating SMS.

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5GNR Temporary Identities

If we discuss about identities there are multiple identities are present in 5G New Radio network as well as LTE Radio Network. Some identities are uses by User Equipment and some are Network Entities identities. So here I am written almost all identities use in network.

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