5G; NR; User Equipment (UE) radio transmission and reception; Part 1: Range 1 Standalone (3GPP TS 38.101-1 version 15.30.0 Release 15)

Introduction: Evolution and Importance of 5G NR Terminal RF Standards

With the commercialization of 5G NR (New Radio) technology, the 3GPP TS 38.101-1 standard defines the minimum radio frequency (RF) requirements for user equipment (UE) operating in standalone (SA) mode within frequency range 1 (FR1, 410 MHz – 7125 MHz). This standard is the core basis for 5G terminal R&D, testing, and certification. This version V15.30.0 (2026-04) is a late maintenance version of Release 15, incorporating years of practical experience and including numerous feature enhancements and coexistence condition updates. Understanding this standard is crucial for comprehending 5G terminal performance boundaries, optimizing design, and ensuring network quality.

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5G NR FR1 Band and Channel Configuration

The standard defines numerous frequency bands from n1 to n86, covering both FDD and TDD duplex modes. Each band supports multiple channel bandwidths (5 MHz to 100 MHz) and subcarrier spacings (15 kHz, 30 kHz, 60 kHz). The flexibility of channel configuration is one of the key features that distinguishes NR from LTE. For example, n78 (3300-3800 MHz), as a mainstream global TDD band, supports up to 100 MHz of bandwidth, while n41 (2496-2690 MHz) provides a maximum carrier aggregation bandwidth of 40 MHz. The standard specifies in detail the allowed channel bandwidth combinations and maximum transmission bandwidth configuration (NRB) for each band, as shown in Table 5.3.5-1.

NR band	duplex mode	typical channel bandwidth	maximum number of RBs (30 kHz SCS)
n78	TDD	100 MHz	273
n41	TDD	40 MHz	106
n1	FDD	20 MHz	51

The channel raster determines the position of the carrier center frequency, while the synchronization raster (synchronization) The raster indicates the possible location of the SSB, facilitating rapid UE search. The standard introduces a 7.5 kHz frequency offset (Δshift) for uplinks in certain FDD and TDD bands to optimize spectrum sharing with LTE. The standard defines two main power levels: Power Level 3 (default 23 dBm) and Power Level 2 (26 dBm). For TDD bands such as n41, n77, n78, and n79, Power Level 2 allows for higher transmit power. Maximum output power must meet tolerance requirements; for example, Power Level 3 has ±2 dBm in regular bands, but has relaxed negative tolerances in bands such as n28 and n71. Furthermore, when using PI/2 BPSK modulation and the network is configured with powerBoostPi2BPSK, a Power Level 3 UE can achieve an equivalent power of 26 dBm in the TDD band, but the duty cycle must be ≤40%.

Maximum Power Back-Off (MPR)

To address the peak-to-average power ratio (PAPR) issues caused by high-order modulation and wide bandwidth, the standard allows the UE to perform power back-off. The MPR value is related to the modulation scheme and RB allocation position.

As shown in the table below:

Modulation Method	External RB Allocation (dB)	Internal RB Allocation (dB)
DFT-s-OFDM PI/2 BPSK	≤0.5	0
DFT-s-OFDM QPSK	≤1	0
CP-OFDM 256QAM	≤6.5	≤3.5

The specific value of MPR depends on the relative position of the channel bandwidth and the center frequency (applicable when the relative bandwidth is ≤4%). For nearly consecutive CP-OFDM allocations, the MPR can be further increased.

Additional Maximum Power Back-Off (A-MPR) and Network Signalling Value (NS)

The network can signal specific NS values to require the UE to meet stricter spectrum emission limits, thus allowing the UE to apply A-MPR to reduce power to avoid interference. For example:

• NS_04: Used in the n41 band to protect adjacent bands (such as CBRS), requiring a steeper spectrum emission template and allowing for a larger A-MPR.
• NS_05/05U: Used in the n1/n84 band to protect PHS systems, with additional spurious emission requirements in the 1884.5-1915.7 MHz band.

• NS_43/43U: Used for n8/n81, protecting E-UTRA Band 20, etc., with spurious emission limits in the 860-890 MHz band.

The A-MPR value may be much larger than the MPR; the corresponding NS configuration must be selected based on the target frequency band and network deployment during design.

Spectrum Emission Template (SEM) and Spurious Emissions

The transmitter's out-of-band emissions must meet SEM requirements. The standard defines a general SEM and has more stringent additional templates for specific NS values. For example, under NS_04, the emission limit change is steeper from the channel edge for n41. Spurious emissions are divided into general requirements and coexistence requirements, the latter designed to protect specific systems (such as LTE, satellites, etc.). Table 6.5.3.2-1 lists the adjacent frequency bands that need to be protected for each NR band and their corresponding limits.

For example, n77 needs to protect E-UTRA Bands 1, 3, 5, 7, and 8, with a limit of -41 dBm/300 kHz in the 1884.5-1915.7 MHz range. Adjacent Channel Leakage Ratio (ACLR) NR ACLR requirements are no less than 30 dB for power class 3 and 31 dB for power class 2. Furthermore, when signaling NS_03U, NS_05U, NS_43U, or NS_100, UTRA ACLR1 33 dB and UTRA ACLR2 36 dB must also be met to protect co-located 3G systems. Transmit Signal Quality EVM requirements become increasingly stringent with modulation order: 17.5% for QPSK, 8% for 64QAM, and 3.5% for 256QAM. Carrier leakage and in-band transmission are also clearly defined, with higher relative leakage allowed, especially at low output power.

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In-depth Analysis of Receiver Characteristics

Reference Sensitivity (REFSENS)

Reference sensitivity is the cornerstone of receiver performance. The standard specifies the minimum sensitivity requirements for each frequency band, channel bandwidth, and subcarrier spacing. For example, the n78 has a sensitivity of -85.7 dBm (2-port) at a 100 MHz bandwidth and 30 kHz SCS. Sensitivity is affected by the uplink channel bandwidth and the selected RB location—the uplink RB should be as close as possible to the downlink band to maximize isolation. For terminals supporting 4 antenna ports, there is an additional gain in sensitivity (ΔRIB,4R = -2.2 dB for n77/78/79).

Adjacent Channel Selectivity (ACS) and Blocking Characteristics

ACS measures the receiver's performance under adjacent channel interference. For frequency bands below 2.7 GHz, the ACS requirement is approximately 33 dB; for frequency bands above 3.3 GHz, the ACS remains at 33 dB, but the interference signal power is greater (-25 dBm).

Blocking characteristics are categorized into in-band, out-of-band, and narrowband blocking, each corresponding to different interference intensities and frequency offsets. For example, in-band blocking requires maintaining throughput even when strong interference (-56 dBm to -44 dBm) is present in or near the receiving frequency band. Out-of-band blocking is evaluated using continuous wave (CW) signals, allowing for a certain number of spurious response exceptions.

Receiver Spurious Emissions and Intermodulation

The receiver's own spurious emissions must not exceed -47 dBm in the 30 MHz to 12.75 GHz range. Wideband intermodulation testing uses a CW signal and a modulated signal to simulate nonlinear effects, requiring high precision, especially in carrier aggregation scenarios.

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Implementation Recommendations and Optimization Strategies

To ensure terminal compliance with standards, the following points should be emphasized during the design phase:

1. Power Amplifier (PA) Linearization: Employ digital predistortion (DPD) or envelope tracking (ET) techniques to reduce MPR, especially under high-order modulation and wide bandwidth. For frequency bands supporting power level 2, a trade-off between efficiency and linearity is required for the PA.
2. Coexistence Filtering Design: Design transmit and receive filters appropriately based on the network signaling requirements of the target market (such as NS values) to suppress out-of-band interference. For example, in n41 deployment, additional filters may be required to meet NS_04 requirements.
   Antenna Matching and Isolation: Multi-band antenna design requires careful attention to port isolation, especially in carrier aggregation or SUL scenarios, to avoid harmonic interference and intermodulation products falling into the receiving band, leading to sensitivity degradation (e.g., harmonic issues in CA_n3-n78 may require an additional 23.9 dB MSD). Receiver Dynamic Range: AGC design must cover a wide dynamic range from the reference sensitivity to the maximum input level (around -25 dBm), while ensuring linearity in the presence of blocking signals. Testing and Verification: Strictly adhere to the TS 38.521-1 testing specifications and cover extreme conditions (temperature -10~55°C, voltage fluctuations, etc.) during the R&D phase.

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Conclusion

ETSI TS 138 101-1 V15.30.0 comprehensively specifies the radio frequency performance of 5G NR FR1 terminals, and its requirements reflect a balance between spectrum efficiency, global deployment flexibility, and coexistence. A deep understanding of this standard helps terminal manufacturers optimize product design, accelerate the certification process, and provide network operators with a reliable user experience.