In addition to the wireless technologies such as Bluetooth and WI-FI that are commonly used in the smart home field, have you learned about carrierless communication technology?
UWB was used in early high-speed data transmission in the near future. In recent years, foreign countries have begun to use their sub-nanosecond ultra-narrow pulses for close-range accurate Indoor Positioning, such as LocalSense wireless positioning system. The first was the use of pulse radio technology, which dates back to the 19th century. Later, the MB-OFDM technology scheme using UWB was proposed by a large company such as Intel. Since the two schemes are completely different and each has strong camp support, the 802.15.3a working group that developed the UWB standard failed to be in the two. The final standard plan was decided and it was handed over to the market.
Its anti-interference performance is strong, the transmission rate is high, and the system capacity is very small. The UWB system has very low transmit power, and communication Equipment can communicate with a transmit power of less than 1 mW. Low transmit power greatly extends system power supply operating time. Moreover, the transmission power is small, and the electromagnetic wave radiation has little influence on the human body, and the application surface is wide.
It is mainly a carrier-free technology that uses a very short time interval (less than 1 ns) for communication, also known as Impulse Radio, Time Domain or Carrier Free communication. . Compared with the ordinary binary phase shift keying (BPSK) signal waveform, the UWB method does not use the cosine wave for carrier modulation and transmits many pulses less than 1 ns. Therefore, this communication method occupies a very wide bandwidth and is due to the power density of the spectrum. Small, it has the characteristics of usual spread spectrum communication.
UWB can achieve data transmission rates of hundreds of Mbit/s to several Gbit/s in a range of about 10 meters by transmitting extremely low power signals over a wide spectrum. UWB has many advantages such as strong anti-interference performance, high transmission rate, wide bandwidth, low power consumption, small transmission power, etc. It is mainly used in indoor communication, high-speed wireless LAN, home network , cordless telephone, security detection, position measurement, radar, etc. field.
Unlike traditional wireless systems where bandwidth is relatively narrow, such as Bluetooth and WLAN, UWB can transmit a series of very narrow low power pulses over wideband. The wider spectrum, lower power, and pulsed data mean that UWB-induced interference is less than traditional narrow-band wireless solutions and provides comparable performance in wired indoor environments.
UWB has the following characteristics:
Strong anti-interference performance. UWB adopts time-hopping spread spectrum signal, and the system has large processing gain. When transmitting, the weak radio pulse signal is dispersed in a wide frequency band, and the output power is even lower than that generated by ordinary equipment. The signal energy is restored during reception, and a spread gain is generated during the despreading process. Therefore, compared with IEEE802.11a, IEEE802.11b and Bluetooth, UWB has stronger anti-interference under the same code rate conditions. The transmission rate is high. The data rate of UWB can reach tens of Mbit/s to several hundred Mbit/s, which is expected to be 100 times higher than that of Bluetooth, and higher than IEEE802.11a and IEEE802.11b.
The bandwidth is extremely wide. UWB uses bandwidths above 1 GHz and up to several GHz. The UWB system has a large capacity and can work simultaneously with the narrowband communication system without interfering with each other. This has opened up a new kind of time domain radio resources in today's increasingly tense frequency resources.
The power consumption is small. In general, a wireless communication system needs to continuously transmit a carrier when communicating, and thus consumes a certain amount of power. UWB does not use a carrier wave, but sends a transient pulse wave, that is, it is sent directly by 0 and 1, and the pulse wave is sent when needed, so the power consumption is small.
Confidentiality is good. UWB confidentiality is manifested in two ways. On the one hand, the time-hopping spread spectrum is adopted, and the receiver can only solve the transmitted data when the spreading code of the transmitting end is known; on the other hand, the spectral density of the transmitting power of the system is extremely low, which cannot be received by the conventional receiver.
Conclusion: Although the actual products and systems currently using this technology are few, most of them are still in theoretical experiments and require more upgrades and innovations. However, its advantages and application characteristics, I believe that there is still a place in the field of smart home in the future.
