Showing posts from December, 2018

Power Saving Mode (PSM) Part II

Home                 LTE                NB-IoT            5G(NR-NSA)   Hi Guys, today we learn more about PSM in Nb-IoT. if you are new at my blog please go through my  Power Saving Mode (PSM) Part I for more details. How does PSM actually work? ·         A UE is PSM enabled only when it sends T3324 timer in Attach/TAU request.   ·         Power Saving Mode configured by providing T3324 active and T3412 extended timers or by configuring "UE requested" timer values. ·         Network provides two options: accept UE requested values or MME configured values for these timers. ·         When PSM configuration is enabled in the Network, the MME accepts the use of PSM and a UE requested value of T3324 timer is received in Attach/TAU request. ·         When PSM is enabled and the Network is configured to accept UE requested values of timers, if T3412 extended timer is not received from the UE along with T3324 in Attach/TAU request, then M

msg3 buffer in LTE

Home                 LTE                NB-IoT            5G(NR-NSA)   What is msg3? Message transmitted on UL-SCH containing a C-RNTI MAC CE or CCCH SDU, submitted from upper layer and associated with the UE Contention Resolution Identity, as part of a random access procedure. What is msg3 buffer? When msg3 is transmitted during initial attach it will be moved to HARQ buffer to handle the retransmission. So msg3 buffer is used to store when UE has msg3. Also MSG3 buffers is sent on SRB0 in initial time. Detailed explanation for understanding: UE can perform RACH either to get sync or initial access. If it is an initial attach with network, UE will send RRC connection request in msg3. If it is a synch RACH then UE will send MAC_CRNTI CE to delete the new RA-RNTI. During Data throughput UE may synch loss then UE will send RRC re-establishment message in msg3. Initial attach synch loss is either TA timer expires or SR count reached MAX. UE synch


Home                 LTE                NB-IoT            5G(NR-NSA)   Hi guys today we are focus on HARQ RTT timer in DL as well as UL for LTE and NB-IOT. What is HARQ RTT Timer? This parameter specifies the min amount of TTIs before a DL HARQ retransmission is expected by the UE. (3GPP TS 36.321 V8.0.0) Simple way to understand: the HARQ Round Trip Time (RTT) timer is defined for UE to sleep during HARQ RTT. When decoding DL TB for one HARQ fails, UE can next retransmission TB after at least HARQ RTT sub frames. While HARQ RTT timer is running, UE need not monitor PDCCH. At HARQ RTT timer expiry, UE resumes PDCCH reception. Two type of HARQ RTT timer is there. HARQ RTT Timer : This parameter specifies the minimum number of subframe(s) before a DL HARQ retransmission is expected by the MAC entity. (3GPP TS 36.321 version 13.3.0 Release 13) UL HARQ RTT Timer : This parameter specifies the minimum amount of subframe(s) before a UL HARQ retransmission grant is e

5G Basic PART II ( Key performance requirements)

Home                 LTE                NB-IoT            5G(NR-NSA)   5G: Key performance requirements of IMT-2020. Hi guys, welcome to Part 2 of 5G learning. Today we will focus on the KPIs of IMT-2020. ITU-R has defined a series of requirements for 5G in the IMT 2020 vision and the 3GPP standards body has been defining the detailed standards to meet ITU requirements. 1)   Data Rate: (IMT2020=5G) Peak Data rate: DL= 20 Gb/s                                                       UL= 10 Gb/s (IMT advanced=4G) Peak Data rate: DL= 1 Gb/s 2)   User experienced (Edge throughput) Data Rate: (IMT2020=5G) User experienced Data rate: DL= 100 Mb/s                                                                              UL= 50 Mb/s (IMT advanced=4G) User experienced Data rate: DL= 10 Mb/s Note:  User experienced Data Rate depends on different use cases like Broadband access in dense areas or Broadband access in crowded areas or Massive