Some terms in mobile communication
1. SINR (Signal to InterferenceNoiseRatio)
2. DoS is the abbreviation of Denial of Service, that is, denial of service. Attacks that cause DoS are called DoS attacks, and their purpose is to make computers or networks unable to provide normal services. The most common DoS attacks are computer network bandwidth attacks and connectivity attacks.
3. The 5G era defines the following three application scenarios:
eMBB: enhanced mobile broadband, as the name suggests, is aimed at high-traffic mobile broadband services;
URLLC: ultra-high-reliability and ultra-low-latency communications, such as unmanned driving services (3G response is 500ms, 4G is 50ms, 5G requires 0.5ms);
mMTC: Big Connect Internet of Things, for large-scale Internet of Things business;
4. V2X is exactly the same as the popular B2B and B2C, meaning vehicle to everything, that is, the information exchange between the car and the outside world. The Internet of Vehicles has laid a new direction for the development of automobile technology by integrating GPS navigation technology, car-to-car communication technology, wireless communication and remote sensing technology, and realized the compatibility of manual driving and automatic driving.
5. MM physical layer anti-eavesdropping technology defense
6. PDCP secret key
7. RACH (Random Access Channel) is a random access channel, which is an uplink transmission channel. RACH is received in the entire cell and is often used for PAGING answer and MS calling/login access.
8. SR, the full name Scheduling Request, is a scheduling request, which is a way for the UE to request resources from the network side for new data transmission. Retransmission does not need to apply for resources through SR, because: if it is adaptive retransmission, the network side will actively issue DCI0 to configure uplink resources; if it is non-adaptive retransmission, the UE directly uses the last RB resource.
SR belongs to the information of the physical layer. The action of the UE sending the SR itself does not require RB resources and can be transmitted through the PUCCH control channel. After the network side successfully decodes the SR signal of a certain UE, it may allocate RB resources to the UE through DCI0, but it cannot guarantee that the network side will allocate the RB every time. Sometimes although the UE sends the SR signal, the network side does not decode it. After the UE sends the SR signal, do not expect that the network side will definitely allocate RB resources at some next moment. In many cases, the UE needs to send SR applications multiple times in order to obtain uplink RB resources.
9. PDSCH frequency domain resource scheduling: In 5G NR, PDCCH is mainly responsible for the transmission of various key control information at the physical layer, including PDSCH frequency domain scheduling information.
10. IoT is the abbreviation of Internet of Things. The literal translation is "Internet of Things", and the accurate translation should be "Internet of Things".
11. IAB: a new generation of information technology, artificial intelligence, biomedicine
12. PDCCH (Physical Downlink Control Channel) refers to the physical downlink control channel. The PDCCH carries scheduling and other control information, specifically including transmission format, resource allocation, uplink scheduling permission, power control, and uplink retransmission information.
13. PCM is pulse code modulation, which completes the function of digitizing voice signals in the communication system. The realization of PCM mainly includes three steps to complete: sampling, quantization, and coding. The discrete in time, discrete in amplitude, and binary representation of the quantized signal are completed respectively. According to CCITT's recommendations, in order to improve the performance of small signal quantization, companding non-uniform quantization is adopted. There are two recommended methods, namely A-law and μ-law. my country has adopted the A-law method. Due to the complex implementation of A-law compression, it is often used. 13 Polyline method encoding, using non-uniform quantization PCM encoding.
14. PRACH (Physical Random Access Channel) is the access channel when the UE initiates a call. After receiving the FPACH response message, the UE will send an RRC Connection Request on the PRACH channel according to the information indicated by the Node B Message to establish an RRC connection.
15. PDCCH (Physical Downlink Control Channel) refers to the physical downlink control channel. The PDCCH carries scheduling and other control information, specifically including transmission format, resource allocation, uplink scheduling permission, power control, and uplink retransmission information.
16. PUSCH: Physical Uplink Shared CHannel (PUSCH, Physical Uplink Shared CHannel) is used to carry data from the transport channel USCH. The so-called sharing means that the same physical channel can be used by multiple users in time sharing, or that the channel has a short duration. Since multiple USCHs can exist in parallel for one UE, and these parallel USCH data can be coded and combined at the physical layer, TFCI can exist on the PUSCH channel. However, the multi-user time sharing of the channel makes the closed-loop power control process impossible, so SS and TPC are not used on the channel. Use in the future).
17. PDSCH: Physical Downlink Shared CHannel (PDSCH: Physical Downlink Shared CHannel) is used to carry data from the transport channel DSCH. In the downlink direction, the transmission channel DSCH cannot exist independently, but can only exist with FACH or DCH. Therefore, the PDSCH as the transmission channel carrier cannot exist independently. DSCH data can be coded and combined at the physical layer, so TFCI can exist on PDSCH, but SS and TPC are generally not used, and information such as power control and timing advance adjustment of the UE is placed on the accompanying PDCH channel.
18. TFCI: Transport Format Combination Indicator (TFCI) is a representation of the current transport format combination. (Channelization coding)
19. UE is an important concept in mobile communications. In 3G and 4G networks, the user terminal is called UE.
20. USRP (Universal Software Radio Peripheral, Universal Software Radio Peripheral) aims to enable ordinary computers to work like high-bandwidth software radio equipment. Essentially, it acts as the digital baseband and intermediate frequency part of a radio communication system.
21. Radio Resource Control (RRC), also known as Radio Resource Management (RRM) or Radio Resource Allocation (RRA), refers to the management, control and scheduling of radio resources through certain strategies and means to satisfy service Under the requirements of quality, make full use of the limited wireless network resources as much as possible to ensure that the planned coverage area is reached, and to improve the business capacity and resource utilization as much as possible.
22. In mobile communications, IMSI (International Mobile Subscriber Identity, International Mobile Subscriber Identity) is used to uniquely identify a mobile user on a global scale. IMSI is stored in HLR, VLR and SIM card and can be transmitted in wireless network and core network. An IMSI uniquely identifies a mobile user and is valid all over the world.
23. Think about it. The wireless network covers a large area. If the IMSI is acquired by criminals when it is transmitted over the network, how dangerous it is. Therefore, it is necessary to use another number to temporarily replace the IMSI for transmission in the network, which is TMSI (Temporary Mobile Subscriber Identity). The purpose of using TMSI to temporarily replace IMSI is to strengthen the confidentiality of the system and prevent illegal individuals or groups from stealing IMSI or tracking the location of users by monitoring the signaling on the wireless path.
24. SRS: used to estimate the frequency domain information of the uplink channel for frequency selective scheduling; used to estimate the uplink channel and used for downlink beamforming
25, DMRS: used for the uplink control and related demodulation of the data channel
26, DRS: only Appears in beamforming mode, used for UE demodulation
27, CRS: used for downlink channel estimation, and demodulation in non-beamforming mode. Scheduling uplink and downlink resources for handover measurement
28. RA-RNTI
Meaning: Corresponding to the position of PRACH-the time-frequency position of the Preamble detected by the eNB, corresponding to the index in PRACH_Config;
theoretical value: 160 (0x0001 0x003C), 0x0000 It is a reserved field, so add one. In fact, it will not be full, and the time-frequency position corresponding to a PRACH_Config does not exceed 10 in a frame.
Use: When responding to an access request, process based on a DCI format on the PDCCH, and add the RA-RNTI identifier in the process. The receiving UE knows the location of its preamble before, of course, also knows this value, so it detects whether there is itself on the PDCCH Corresponding RA-RNTI; if yes, it means that the access is responded, and read the RA Response message (MSG2) on the PDSCH according to the indication on the PDCCH.
29. CORESET is a set of physical resources (that is, a specific area on the NR downlink resource grid) and a set of parameters used to carry PDCCH/DCI. It is equivalent to the LTE PDCCH region (the 1, 2, 3, and 4 OFDM symbols in the subframe). But in the LTE-PDCCH region, the PDCCH always spreads over the entire channel bandwidth, while the CORESET region of NR is limited to a specific region in the frequency domain.
30. C-RNTI: Basically has nothing to do with random access itself, and is related to the cause and status of the UE access request:
If the UE is in RRC_CONNECTED mode, it means that C-RNTI has been allocated, and it needs to be reported during access; if the UE is in IDLE mode , It means that there is no C-RNTI, if it is to request RRC connection, the eNB may allocate a C-RNTI if it agrees in the subsequent Msg4; related to the random access process is temporary C-RNTI, which is the eNB in Msg2 in the competition mode One is always sent to identify the UE in the subsequent Msg. Of course, the UE has a C-RNTI or does not need a TC-RNTI.