5G
Overview of 5G Networks
• 3GPP defines three major scenarios for 5G: (Embb/Mmtc/URLLC)
• Bandwidth requirements and latency are the main driving forces behind the development of 5G (Incorrect)
• The following are directions for the development of 5G networks: (Heterogeneous network integration / Ultra-dense cells / Cloud computing / Elastic resource management and network intelligence)
• The 5G network side adopts (SDN/NFV) technology
• NFV aims to use (virtualization) methods to implement network functions (such as gateways and firewalls) that originally ran on dedicated middle devices (middlebox) in a software manner.
• The core idea of SDN is (separation of control and data plane)
• The independent networking of 5G NR is documented in which 3GPP protocol version (Release 15)
• The peak rate of 5G is (10Gbps), latency (1ms), and the number of connections (1 million) per square kilometer
• In the key performance indicators of 5G networks, the requirement for high-speed mobility is (500km) per hour
5G Networking Technology
• The independent networking method of 5G includes (SA/NR+NGC)
• The characteristics of NSA (Non-Standalone Networking) are: (5G base stations cannot operate independently and must use dual connectivity through LTE base station instructions, with 5G only serving as an enhancement for the data pipeline / UE must be a terminal that supports dual connectivity / mainly solves the problem of incomplete initial coverage of 5G and frequent interoperation between 5G and 4G)
• In the case of discontinuous coverage of 5G NR, it is recommended to use NSA networking (Correct)
• NSA can share the core network with LTE (Correct)
• In which frequency bands will 5G be deployed? (3.3-3.6G/4.8-5.0G)
Key Technologies of 5G Networks
• The key technologies of 5G wireless access mainly include (massive MIMO / ultra-dense networking UDN / full spectrum access / new multiple access / new multi-carrier / direct terminal connection)
• The advantages of the massive MIMO technology in 5G include (significant improvement in system capacity and energy efficiency / reduction in both uplink and downlink transmission energy / users will have orthogonal channels, eliminating interference and noise / statistical characteristics of the channel tend to stabilize)
• The correct statement about 3D beamforming is (increases vertical beam direction)
• What are the characteristics of 5G millimeter wave communication technology? (It is a typical line-of-sight transmission method / has atmospheric windows and attenuation peaks / severe attenuation during rain / has strong penetration capability against dust and smoke)
• The correct descriptions of the advantages of 5G millimeter wave communication technology include (can use wide frequency bands, providing tens of GHz bandwidth / beam concentration improves energy efficiency / good directionality, less affected by interference)
• What non-orthogonal multiple access technologies have been proposed by Chinese manufacturers? (SCMA/MUSA/PDMA)
• The advantages of 5G D2D communication are (improving cellular spectrum utilization / increasing network capacity / reducing base station traffic load / terminal close-range communication, high speed, low latency, low power consumption)
5G Network Protocols and Architecture
• The three planes of the 5G network architecture are (Access Plane / Forwarding Plane / Control Plane)
• In the 5G standard, the BBU function is restructured into two functional entities: (CU) and (DU)
• The interface between two 5G base stations is (Xn)
• The functions of the 5G network element AMF include (registration area management / mobility management control / idle state UE addressing)
• The following are part of the 5G NR control plane protocol stack sub-layers: (RRC/PDCP/RLC/MAC)
• In the 5G air interface protocol layer, the highest layer of the Uu control plane is (RRC)
• The SDAP function in 5G includes (mapping QoS flows to DRB data radio bearers / adding QFI tags to data packets)
• The PDCP in 5G has added sorting and duplication functions compared to LTE (Correct)
• The user plane in 5G differs from LTE in that it has added the SDAP sub-layer (Correct)
• The minimum granularity of QoS management in 5G is QOS FLOW (Correct)
• The correct statements regarding RRC state transitions in 5G NR are: (RRC-CONNECTION state can transition to RRC-INACTIVE state / RRC-IDLE state and RRC-CONNECTED state can transition bidirectionally / RRC-IDLE state cannot transition to RRC-INACTIVE state)
5G Physical Layer
• The waveforms supported by PUSCH in 5G include (DFT-S-OFDM/CP-OFDM)
• Which of the following modulation methods is unique to DFT-S-OFDM? (π/2-BPSK)
• What parameters are included in the 5G parameter set? (SCS+CP)
• The subcarrier spacing in 5G NR is (15kHz/30kHz/60kHz/120kHz/240kHz)
• The following belong to the 5G frequency bands: (3300-3400MHz/3400-3600MHz/4800-5000MHz)
• In the first version defined in 3GPP Rel-15, the supported subcarrier spacing in the frequency range of 24GHz-52.6GHz is (60kHz/120kHz)
• The significance of dividing the SUL frequency band is (to be used in conjunction with 3.5GHz to supplement uplink coverage)
• In 5G NR, a resource block is defined as (12) consecutive subcarriers
• The maximum bandwidth supported in the sub-6GHz frequency band in 5G is (100MHz)
• The maximum number of PRBs supported in a single cell in 5G is (273 PRBs)
• The channel bandwidth utilization rate in 5G NR can reach up to (0.9828)
• When using different numerologies in the channel bandwidth, the principle for selecting the minimum guard band is (determined by the adjacent numerology)
• The modulation method of the PBCH signal in 5G is (QPSK), used for broadcasting system messages MIB
• The NR MIB does not include the following field (PLMN Identity)
• The composition of SSB in 5G NR includes (PSS/SSS/PBCH)
• In the frequency domain, the SS/PBCH block consists of how many consecutive RBs (20)
• The lengths of the synchronization signals PSS and SSS in 5G NR occupy (127 subcarriers) in frequency domain resources
• The coding method used for the PUSCH channel is (LDPC)
• The coding scheme for the eMBB scenario in the 5G control channel is (Polar code)
• The information carried by UCI in PUCCH in 5G includes (CSI/ACK/NACK/scheduling request)
• Which of the following PUCCH formats does not support multiplexing capability in the same PRB? (PUCCH format 2/PUCCH format 3)
• What are the uplink reference signals related to PUSCH? (DM-RS/PT-RS)
• In the physical layer reference signals of the 5G network, the only signals accompanying PUSCH and PDSCH channel transmission are (PT-RS)
• The function of the downlink reference signal CSI-RS in the physical layer of the 5G network is (downlink channel measurement / RSRP calculation and mobility processing / time-frequency tracking)
• The phase tracking reference signal (PT-RS) is a new feature in NR, mainly used for low frequency. (Incorrect)
• For one service cell, the base station can configure multiple DL BWPs and multiple UL BWPs for the UE through specialized RRC signaling, with a maximum of how many for each (4)
• 5G NR has (1008) unique physical layer cell IDs
• For 5G NR, how many milliseconds does a wireless frame occupy? (10)
• The length of one wireless subframe in 5G is (1ms)
• In 5G NR, one 1ms subframe contains (multiple) time slots
• The flexible frame structure of 5G NR mainly includes (full uplink / full downlink / uplink dominant / downlink dominant)
• The types of OFDM symbols in the time slots of the 5G frame structure are divided into (downlink / flexible / uplink)
• The basic time unit of the 5G NR frame structure is (Tc)
• The lengths of the 5G wireless frame and subframe are fixed, allowing for better coexistence between LTE and NR (Correct)
NB-IoT
• What multiple access technologies are used for NB-IoT uplink and downlink? (SCFDMA/OFDMA)
• What is the subcarrier spacing for NB-IoT? (15K)
• What are the options for uplink subcarrier bandwidth in NB-IoT? (3.75kHz/15kHz)
• Which type of network cannot directly deploy NB-IoT? (TDD-LTE network)
• The NB-IoT system has (504) different cell IDs
• In addition to the IDLE state, NB-IoT introduces a new PSM state, where the terminal turns off RF reception and enters a sleep state. How long can this state last at most? (310h)
• The cycle of the NPBCH channel is (640ms)
• The duplex mode adopted in the R13 version of NB-IoT technology is (FDD half-duplex)
• The wireless frame length of the NB-IoT system is (10ms)
• The main application scenarios for NB-IoT include (smart metering / smart lamp poles)
• The incorrect statement about NB-IoT is: (sensitive to delay requirements) The correct ones are: INBAND deployment means that the NB-IoT carrier is deployed within the LTE working bandwidth / coverage enhancement of 20dB / downlink uses 15kHz OFDMA technology, with each channel being 15kHz, totaling 12 sub-channels
• NB-IoT has wide coverage, stronger than 2/3/4G networks, with a gain of (20dB)
• The downlink carrier bandwidth for NB-IoT is (180kHz)
• In the NB-IoT system, the sending period of NPSS is (10ms), and the sending period of NSSS is 20ms
• In the NB-IoT system, the NPBCH transmission occurs in which subframe of each wireless frame? (Subframe 0)
• In the NB-IoT system, the maximum number of wireless ports supported in the downlink is (2)
• The number of users that can be connected per cell in NB-IoT is (50,000)
• The defined downlink physical channels in NB-IoT are (NPBCH/NPDCCH/NPDSCH)
• The defined uplink physical channels in NB-IoT are (NPRACH/NPUSCH)
• The uplink subcarriers in NB-IoT may have (12/48)
• The modulation methods supported by NPUSCH are (BPSK/QPSK)
• Which deployment method needs to consider interference issues with the LTE system? (Guard band deployment / internal band deployment)
• The transmission modes supported by the RLC sublayer in the NB-IoT system include (TM/AM)
• In NB-IoT, resource scheduling for uplink and downlink is based on (RU/subframe)
• In the default state of NB-IoT, what working states exist? (connected/idle/psm)
• The interface between MME and SCEF is (T6a)
• The core network of the NB-IoT system mainly includes (MME/SGW/PGW/SCEF) network elements
• The SCEF network element introduced in the NB-IoT system has the following functions: (uplink and downlink non-IP data delivery / T6 connection management / non-IP data transmission authorization check)
• The following processes (RRCConnectionReestablishmentRequest/RCConnectionReestablishment/RCConnectionReestablishmentComplete/RCConnectionReestablishmentReject) may include signaling flows during the RRC connection re-establishment process
• NB-IoT supports 3 SRBs, which are (SRB0, SRB1, SRB1bis)
• The definition of a good point during the NB-IoT cell site testing is (RSRP > -80dBm, SINR > 20), download rate reaches 15kbps, and the ping delay requirement is less than 1.5s
• How does NB-IoT increase coverage? (By reducing the bandwidth of subcarriers, increasing power spectral density / repeating transmissions in time to gain time gain)
• The following are optimization measures for external interference in NB-IoT: (installing filters / station sweeping / shutting down interference sources / increasing isolation)
• In NB-IoT, unreasonable neighbor planning may lead to (weak signals / poor signal quality / reselection failures / disconnections)
• The principles for optimizing coverage interference in NB-IoT include (first optimizing RSRP, then optimizing SINR / prioritizing weak coverage, then optimizing overlapping coverage areas / eliminating weak coverage; reducing cross coverage)
• The length of CP in the NPRACH channel can be configured to (66.7us/266.7us)
• The options for cell reselection supported by NB-IoT are (idle state same-frequency cell reselection / idle state different-frequency cell reselection / redirection)
• The PCI planning for NB-IoT must not be consistent with the existing LTE TAC (Correct)
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