The NB-IoT MAC protocol is mainly responsible for data transfer (Data Transfer) and physical resource/radio resource allocation (Radio Resource AllocaTIon). This paper focuses on wireless resource allocation, and illustrates the planning of NB-IoT radio resources. Since the physical layer has less bandwidth available than LTE (180 kHz one carrier), the physical layer procedure is also very different from the previous one. Considering the NB-IoT enhanced signal coverage requirements, the 3GPP standard development team uses the "repetitive transmission" method to obtain the time domain. Gain, to achieve coverage enhancement (CE): In the standard specification, downlink transmission only allows cross-subframe Scheduling, uplink transmission supports cross-frame and cross Subcarrier scheduling. The NB-IoT manages the radio resources required for data transmission between the evolved Node B (eNB) and the User Equipment (UE) in a centralized control manner. As with the LTE system, the UE transmits or receives data and is subject to the eNB indication. The downlink transmission assignment (Uplink Grant) and the uplink transmission grant (Uplink Grant); that is, the downlink transmission control indication (Downlink Control Indicator, DCI), the uplink part uses the DCI format, and the downlink part is the DCI N1. The format, paging (Paging) part uses the DCI N2 format. The UE periodically monitors/monitors the area transmitted by the DCI during the process of linking with the base station, that is, a narrowband physical downlink control channel (NPDCCH), also known as a search space. After receiving the DCI belonging to the UE, the UE receives the data according to the content indication to the corresponding data transmission area, that is, the narrowband physical downlink shared channel (NPDSCH). Based on the characteristics of the NB-IoT cross-branch scheduling, the LTE uses the DCI to inform the UE of the location of the resource block and the number of resource blocks in the sub-frame data, so that the UE knows that the data is located in the "frequency interval". In the NB-IoT, it informs a Scheduling Delay (standardly called k0) and the resource block length, so that the UE knows that its own data is located in that "time interval". For the NB-IoT resource allocation and scheduling related parts, there are the following instructions. Similar to LTE, the UE can obtain DCI information by searching for a specific interval, which can reduce the unnecessary power consumption of the UE to blindly unrelated data. In NB-IoT, the search space is presented as a time interval; by informing the UE of relevant parameters in advance, such as the common search space in the NB-IoT System InformaTIon Block Type 2 (SIB2-NB) (Common Search Space) parameters, the RRC ConnecTIon Setup Message in the Random Access process, with the UE Specific Search Space parameter, so that the UE can know at which time range has the opportunity to blindly solve itself. DCI. Under the standard specification, the definition of the search space has great flexibility. In terms of length, the appropriate length can be selected according to the characteristics of the served UE. Meanwhile, in the same search space, the standard can be further selectively divided according to the standard. 4, 8 and other four ratios, as the DCI transmission time of different UEs, the divided length is the number of repeated transmissions of the DCI (T1CSS can select more kinds of proportional division). As shown in Figure 1, the blue area is set to the search space length Rmax (this example is set to 8), according to the division of the four ratios, in order R = Rmax / 8, R = Rmax / 4, R = Rmax /2, R=Rmax/1, for example, 1, 2, 4, and 8, respectively, and R is the number of repetitions. At this time, the time block covered by R is called the candidate block (Candidate). The selected division ratio can also be regarded as the number of candidate blocks included in this search space. In addition, the time position of different search spaces can be adjusted through parameter settings, so that too many UEs are in the same search space setting, and the UEs that the base station can serve in unit time are limited. The different parameters and proportions will affect the number of UEs that the base station can serve in a unit time, as well as the CE performance. Therefore, the implementation can be adjusted according to the scheduling policy decided at the moment. After the UE selects to camp on a certain base station, the UE monitors the corresponding search space according to the current online state. The current standard defines the Type1-NPDCCH common search space (T1CSS) and the Type2-NPDCCH common. Search space (T2CSS), NPDCCH UE-specific search space (USS) and other three different search spaces: T1CSS When the UE is idle (Idle), the T1CSS is monitored according to a Default Paging Cycle between the core network (CN). In view of the fact that the UEs of different CE levels are the same T1 CSS length setting, the candidate block partitioning according to the standard may have more choices to satisfy the repeated transmission times of the UEs of each CE level; when the UE searches for space and solutions in this paging cycle When the DCI is received and the paging message is correctly received, the UE performs a random access procedure and adjusts the searched space to T2CSS. T2CSS When the UE is not registered with the nuclear network, or is registered but is in an idle state, if the UE wants to transmit data or receives a paging message from the base station, the UE starts a random access procedure. At this time, the UE sets the blind DCI according to the T2CSS setting. USS The Mesh Coil Vape Disposable technology is the latest disposable pen manufacturing technology. The Vape Pen produced is not easy to paste the core, and the smoke is more stable and has better flavor. Mesh Coil vape,Mesh Coil Tanks,Mesh Coil Vape,Disaposable Mesh Coil Vape,Mesh Coil Disposable Vape tsvape , https://www.tsecigarette.com
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