Knowledge tips: Ultra-Broadband Wireless Access

This article describes in detail the origins of the ultra-wideband wireless access technology, developed from the wireless UWB technology, that is, the pulse radio technology. It is used in a broader field and is integrated with our daily lives. It not only facilitates entertainment and work.

Ultra-Wideband Wireless Access Technology

According to the problems of serious narrowband interference and average power ratio of MB-OFDM signal in ultra-wideband Communication System, combined with the current situation of China's spectrum resource allocation and hardware implementation conditions, A MB-OFDM ultra-wideband MB-OFDM-UWB communication system based on orthogonal extension and interweaving can be designed by using ultra-wideband wireless access technology. System design parameters include channel division scheme, signal transmission form, data packet structure, transceiver implementation framework, and so on. This technology extends the bitstream transmitted by the sub-carrier to all sub-carriers of the corresponding sub-band, and then the extended data streams transmitted by each sub-carrier are intertwined across all sub-bands.

In this way, on the one hand, we make full use of the frequency diversity between the system sub-carrier and sub-band, greatly enhancing the MB-OFDM-UWB system's ability to resist narrow band interference; on the other hand, through orthogonal extension and interweaving of the transmitted data, the data entering the multi-carrier modulation tends to be Gaussian distribution, reducing the peak side lobe of the Self-correlation function of the transmitted data, the peak-to-average power ratio of OFDM-UWB signal is reduced, and the spectrum structure of the signal is also improved. Theoretical analysis and simulation results show that, the ultra-wideband Communication System Based on this structure has many advantages in terms of system capacity, bit rate performance, anti-interference, Average Signal Peak power ratio, and system implementation complexity.

Trace back to the origins of ultra-wideband wireless access technology, starting from the following: according to the definition of FCC, the ultra-wideband technology refers to a system with a relative bandwidth-to-center frequency ratio) greater than 0.2 or a bandwidth over MHz. The FCC allocates 3.1 ~ The 10.6GHz band is used as the applicable band of the ultra-wideband system. In this band, The transmit power of the ultra-wideband device must be lower than-41.3dBm/MHz to coexist with other wireless communication systems.

Early UWB technology used pulse radio technology. The pulse length of the pulse technology is usually in sub-nanosecond magnitude, the signal bandwidth often reaches several GHz, and has a very small duty cycle, this results in a low average transmit power of the pulse UWB device, which is 1/100 to 1/1000 of the existing Bluetooth system. The advantage of low transmit power is that the transmit power of the UWB device can be reduced to the background noise level, so it can share the band with other wireless systems. Moreover, the extremely low transmit power also makes the ultra-wideband device have the advantages of low energy consumption, low cost, and good confidentiality.

In addition, low Duty Cycle Pulse UWB equipment also has good performance in multi-path interference resistance. The disadvantage of the pulse UWB system is that the spectrum utilization rate is low. The residual out-of-band frequency components in the Pulse Forming filter process may produce unpredictable interference, and it is difficult to implement the pulse UWB system.

The mainstream UWB technology solution is to improve the traditional carrier modulation technology so that it can use a large bandwidth to achieve a high capacity. The non-pulse UWB scheme mainly includes multi-band OFDMMB-OFDM and DS-CDMA, which can be regarded as the ultra-wideband improved of OFDM and CDMA respectively. The MB-OFDM is still based on 128 points of OFDM transmission, but the bandwidth of each sub-carrier increased from several kHz to 4 MHz. The DS-CDMA adopts the code rate of over 1 GCPs, which is very different from the traditional CDMA technology of several hundred kcps. Most of the theoretical knowledge and practical experience accumulated by people on these two technologies are still applicable to the UWB technology, but they should pay special attention to Interference Problems, spectrum planning, low energy consumption, and other specific technical aspects.

Over the past few years, the standardization of UWB technology has been mainly carried out in the IEEE 802.15 framework. IEEE 802.15 is a standardization group for Wireless Personal Network (WPAN. The WPAN system is mainly used for interconnection between individual devices, with a coverage of less than 10 m and features low cost and low energy consumption. In the 802.15 protocol, 802.15.3a specifically considers adopting the UWB technology to further increase the WPAN speed. As one of the alternatives of 802.15.4, pulse radio UWB technology is used to provide high-precision ranging and positioning services with a precision of less than 1 MB), and to achieve a longer working distance and ultra-low power consumption.

The UWB technology in WPAN is mainly used to replace more and more electronic devices with wireless connections, making information exchange between various devices in the home or office more convenient, flexible, and fast. The Application of UWB technology in digital homes can connect electrical appliances in consumer homes with a wireless network, so that various audio and video information can be transmitted and exchanged between these electrical appliances. The Application of uwb wpan Technology in the digital office can connect all electronic office equipment via wireless networks, saving the trouble of wiring and making the office environment more convenient and flexible. The UWB technology is used for the interconnection of conference equipment. It enables high-speed wireless connections between the terminal devices of the participants and between the devices and the projector to exchange and display multimedia content in a timely manner.

The Application of UWB technology on personal portable devices allows personal terminals to instantly download a large amount of data from the Internet or local area network, so that most of the data is stored in the storage space of network servers, instead of storing it in a personal terminal. In this way, powerful personal computers may become very small and easy to carry. With the development and improvement of the UWB technology, we can even use it to interconnect different parts of a personal terminal. This makes it easier for users to accept and use.

The development of ultra-wideband wireless access technology comes from the Development of Ultra-Wideband technology, which can be said to be an upgraded version of Ultra-Wideband. Each Wireless Technology influences and promotes each other. It can be combined or integrated to provide future network development materials.