In a cellular system, handover can be defined as a procedure to transfer a User Equipment (UE) and its context from a source cell to a target cell when source cell signal becomes bad so it handover the UE to target cell to continue the UE session. In LTE, Handover Mobility Support for UEs in ECM-CONNECTED … Read more
The mobile operators are or have moved to voice over LTE (VoLTE). Globally, voice is still the major chunk of ARPU for the telecommunications industry. However, basic voice may not be enough to remain relevant in an LTE environment which is data services by default, because subscriber communication is shifting from plain voice to HD … Read more
The quality of Voice service plays and will play an important role in the evolution of the telecommunication system. Voice subscribers are becoming habitual of Voice over IP (VoIP) services that provide extended audio bandwidth be it Skype or Whatsapp Calling. They also expect the same high quality from mobile voice services. With the maturity … Read more
VoLTE IMS Protocols In IMS subsystem, the critical protocols are the Session Initiation Protocol (SIP), SigComp, Real-time Transport Protocol (RTP), RTP Control Protocol (RTCP) and IP Security (IPSec) and Diameter. These protocols are very important because these are the ones impacted by the UE or have a direct impact on UE operation. In a VoLTE … Read more
NB-IoT or NB-LTE is a new 3GPP radio-access technology. It is not fully backward compatible with existing 3GPP devices however it is designed to achieve excellent co-existence performance with legacy GSM, GPRS and LTE technologies. NB-LTE requires 200 kHz minimum system bandwidth for both downlink and uplink, respectively. The choice of minimum system bandwidth enables … Read more
3GPP has defined a set of frequency bands for which NB-IoT can be used. 3GPP TS 36.101 from Release 13 provides the list of the supported bands: 1, 2, 3, 5, 8, 12, 13, 17, 18, 19, 20, 26, 28, 66 and Release 14 added the bands: 11, 25, 31 and 70. Later, 3GPP Release 15 … Read more
NB- IoT frame structure is illustrated in the below picture. At the highest level, it starts with a hyperframe cycle where one hyperframe cycle has 1024 hyper frames and each consisting of 1024 frames. One frame consists of 10 sub-frames and each subframe is dividable into two slots each of 0.5 ms which is similar … Read more
The NPSS and NSSS helps UE to synchronize downlink to an NB-IoT cell. These are transmitted in certain subframes based on an 80-ms repetition interval. By synchronizing to NPSS and NSSS, the device will be able to detect the cell identity number (NB-IOT PCI). NPSS and NSSS are designed to allow devices to use a … Read more
NPBCH stands for narrow band physical broadcast channel similar to PBCH in LTE Technology. The NPBCH is used to deliver the NB-IoT Master Information Block (MIB), which provides essential information for the NB-IOT UE to operate in the NB-IoT network. NPBCH uses a 640 ms TTI, but within the TTI only subframe 0 is used … Read more
When a NB-IOT UE accesses a cell, it follows the same principle as for LTE: It first searches a cell on an appropriate frequency. Decode NPSS and NSSS for NCellID. After decoding NCellID, UE decode the NB-MIB Information transmitted over NPBCH, but there it can get to know NB-LTE deployment mode i.e. In-band, Guard-band or Standalone, the schedulingInfoSIB1, … Read more