ICACT20230137 Slide.15
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Thanks for your attention! Welcome any comment or question.
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ICACT20230137 Slide.14
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We referred to 3GPP standard documents, TS 38.331 and TS 36.331, as references, and to implement ns-3 simulation environment, we referred to nsnam, 5g-lena site, and nr module data.
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ICACT20230137 Slide.13
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This slide presents the conclusion of this paper.
ns-3 5G LENA source code, the latest standard was not reflected because the RRC layer reuses LTE RRC.
Our implementation consists of moving the RACH information in the SIB2 message to SIB1 in the ns-3 code so that initial access can be made immediately even when only the SIB1 message is received.
As a result of the simulation, it was found that the initial connection can be made faster when using the proposed method compared to the existing LTE RRC.
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ICACT20230137 Slide.12
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Table 3 shows the UE RRC State changing as the simulation time progresses. As expected, in the case of the existing LTE RRC, an access attempt is made through the RACH process only after SI (SIB2) is received, so the initial access can be completed at 0.045s. On the other hand, in the case of the 5G NR RRC code we implemented, it was confirmed that the initial connection can be made at 0.020s, which is faster than the LTE-based method, because a connection attempt can be made immediately when SIB1 is received.
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ICACT20230137 Slide.11
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We implemented the initial access process discussed in the previous slide in the ns-3 simulation tool, and tested the network initial access time of UE terminals in LTE and 5G NR.
System information message transmission cycle setting implemented with NS-3 is the same as shown in the table.
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ICACT20230137 Slide.10
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This slide shows the initial access process based on 5G NR.
Unlike in LTE, if MIB and SIB1 messages are received after starting cell search, RRC connection is established by immediately attempting RANDOM ACCESS in the CAMPED NORMALLY state.
The reason why RANDOM ACCESS can be performed without receiving SIB2 in 5G NR is that RACH information is included in SIB1 as confirmed in the table on the previous slide.
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ICACT20230137 Slide.09
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This slide shows a flow chart for LTE-based initial access implemented in the existing ns-3 project, 5g lena.
When the UE starts cell search, it first waits for MIB and SIB1 message reception.
The UE must receive the MIB message to receive the SIB1 message, and then the UE can stay in the cell normally.
Afterwards, the UE receives SIB2 including RACH information for RRC access, goes through the RANDOM ACCESS process, attempts RRC connection, and if the network accepts it, RRC connection is established
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ICACT20230137 Slide.08
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We implemented the initial access process based on LTE and 5G NR using the ns-3 simulator.
As can be seen in the table, in 3GPP LTE, SIB2 message contains information about RACH, and in 5G NR, SIB1 contains information about RACH.
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ICACT20230137 Slide.07
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On the other hand, in 5G NR, since the UE can receive RACH information even if it receives only MIB and SIB1 messages, it can start the RACH process and transmit RRC request messages.
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ICACT20230137 Slide.06
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This slide shows the system information sequence diagram between UE and BS for initial access in LTE.
In LTE, all MIB, SIB1 and SIB2 have to be received in order for the UE to start the RACH process and transmit the RRC request message for RRC connection to the network (BS).
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ICACT20230137 Slide.05
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ns-3 is a representative tool for 5G NR mobile communication network simulation.
In the 5G LENA project, ns-3 provides some of the 5G NR functions up to the latest 3GPP standard Rel-15, enabling simulation based on more recent standards.
However, even in the 5G LENA project, the RRC layer reuses the RRC provided by the existing LTE, so RRC for the latest 5G NR cannot be used.
In this paper, we implemented 5g nr initial access process and evaluate performance using the Ns-3 simulation, it was found that the 5G NR-based RRC we implemented is able to achieve an RRC connected state more quickly than LTE.
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ICACT20230137 Slide.04
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In LTE, since MIB, SIB1, and SIB2 contain information for accessing cells, they contain crucial information for the UE.
In particular, MIB contains information for receiving SIB1, SIB1 contains cell access information, and SIB2 contains RACH (Random Access Channel) information for Uplink synchronization in a cell.
On the other hand, SIB1 in 5G NR includes information on cell access as well as RACH information and scheduling information on how other SI blocks beyond SIB2 are transmitted.
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ICACT20230137 Slide.03
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3GPP started establishing 5G NR standards in 2016, and standard documents up to Rel.17 were finalized.
Among the 5G NR standards, TS 38.331, an RRC (Radio Resource Control) protocol standard, describes contents related to radio access between a UE and a BS.
The step of initial access to the BS includes a process of receiving system information blocks such as MIB (Master Information Block), SIB1 (System Information Block1), and SIB2 (System Information Block2) after DL (Downlink) sync through SSB (Synchronization Signal Block).
Here, MIB and SIB1 are transmitted as one message through the PBCH (Physical Broadcast Channel) and PDSCH (Physical Downlink Shared Channel), respectively, and SIB2 is included in a message called SI (System Information) and transmitted through the PDSCH.
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ICACT20230137 Slide.02
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This is abstract of our paper.
RRC layer protocol define a procedure for how a UE initially accesses a base station. UE can obtain information for cell access through system information blocks such as MIB(Master Information Block) and SIB (System Information Block) transmitted by the base station.
In LTE, it is necessary to access a cell through MIB, SIB1, and SIB2.
However, in 5g nr, since SIB1 includes LTE¡¯s SIB2 information, it is possible to access a cell with only MIB and SIB1.
In this paper, we implemented 5g nr initial access process using ns-3.
We also evaluated performance of 5g nr initial access procedure compared to LTE.
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ICACT20230137 Slide.01
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Hi everyone, my name is Seokjoon Hong. I am going to present about ¡°5G NR based initial access procedure simulation environment implementation including system information using ns-3 simulator¡±
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