5G products are constantly being updated. From the GSA statistics, 129 models have been published in 2019, and countries have also issued 5G spectrum licenses, which is expected to drive huge 5G-NR network and device development opportunities; in this article, we will explore the 5G terminal product design challenges from 5G communication systems and product RF design, such as RF related design, such as active antenna array, Beam Forming, power consumption and path loss, OTA (Over-the-air) test challenge.
1. High speed / large capacity / wide area coverage requirements ～Solution for 5G NR at the mm-wave.
mm-Wave has more than 100 times the transmission speed defined by 3GPP and the demand for wider coverage, and it is estimated that there will be 50 billion connected devices in 2020. In this case, it needs up to 1,000 times of capacity, and it depends on high frequency millimeters. Wave assisted. The reason is that millimeter waves provide a very large available bandwidth. For example, the 28 GHz band itself has an 800 MHz bandwidth, while the 37 to 40 GHz provides a 3,000 MHz bandwidth. As long as the bandwidth is larger, the transmission speed and capacity will be automatically increased, thereby meeting the goal of high transmission speed and high capacity of 5G. Overall, the new frequency band will bring a lot of bandwidth, and will also be introduced with different new technologies, such as MIMO technology in the 4G era, and millimeter wave is the introduction of beamforming technology.
2. In high-frequency wide components, the transmission system must be able to convert the bit data into millimeter-wave signals. After transmitting and receiving via the transmission path, the bit format in the wireless signal is re-removed and retrieved. The difficulty of the whole process will be More high than previous technology thresholds.
3. What's design challenge on the5G equipment ?
a. Power Loss.
Because the wavelength of the millimeter wave is very short, the wavelength of the water vapor and oxygen molecules in the actual environment will affect its transmission. The power emitted by the millimeter wave from the base station is transmitted to the terminal, which is easily affected and penetrated by anything in the path, and the attenuation is fast, so the power reaching the terminal is much reduced, which is the loss problem.
b. Antenna design.
Today's mobile phones include a variety of wireless technologies, including Bluetooth (BT, LE, EDR), GPS, WiFi (a, b, g, n, ac, ax), NFC, wireless charging technology, and 2G, 3G, 4G antenna.
In this design, each mobile phone has at least ten antennas.However, the addition of 5G millimeter wave technology is further limiting the number of mobile phone antennas, so the location and size of the antenna are very important. Although the millimeter wave is often shorter, the number of antennas that can be inserted can be more, but the mobile terminal product is used in the hand. If the antenna is placed in the range of the hand, the transmitted signal will be worse.
Finally, 5G NR knowledge points under popular science
1. 5G NR also launched stand alone and non-stand alone. For non-stand alone, mobile devices can use both 4G and 5G networks and stay connected to both LTE eNBs and 5G gNBs.
2. 5G NR uses the Orthogonal Frequency Division Multiplexing (OFDM) version. The specific OFDM version for the 5G NR downlink is a cyclic preamble; OFDM is also the same waveform that LTE uses for the downlink signal. However, unlike LTE, 5G NR uses waveforms based on CP-OFDM and DFT-S-OFDM in the uplink.
3. Another difference from LTE is that 5G NR allows for extremely variable subcarrier spacing SCS (15K, 30K, 60KHz).
4. The LTE subcarrier spacing is almost always at 15 kHz, but the 5G NR gives more flexibility, making the subcarrier spacing set to 15 kHz x 2n. At 5G NR, the maximum allowable subcarrier spacing is 240 kHz and is reserved for use with a 400 MHz carrier bandwidth.
5. In terms of spectrum characteristics, most operators will have low-, medium-, and high-band three-layer networking, with a low-band 700MHz overlay, 2.5GHz as a capacity layer, and a millimeter-wave as a high-capacity layer (hotspot).
