RF Front-end Design And Implementation Of Broadband WLAN With Multiple Antennas

Wireless Local Area Network(WLAN) is one of the most effective methods by connecting wireless devices with the Internet to complete data transmission in short distance. In pace with the expansion of wireless Internet business and the rapid popularity of wireless terminal equipment, in face of the high-density access and high parallelism situation, the IEEE 802.11 ac as one of the next generation WLAN standard can meet the requirement of user demand for high rate and high throughput.The 802.11 ac standard has many excellent features, such as operation at 5GHz band, channel bandwidth up to 160 MHz, support 8 spatial streams, the maximum data transfer rate up to 6.93 Gbps in theory, etc. According to the physical layer requirements of 802.11 ac standard, this paper focuses on researching the RF front-end of broadband WLAN system and proposes a specific design and implementation scheme about broadband multi-antenna RF front-end which has 665 MHz operation bandwidth and 8×8 MIMO structure. The main work of the paper includes the following aspects.Firstly, the advantages and disadvantages of wireless transceiver common structure and the feature of MIMO technology are summarized. According to the physical layer requirements of 802.11 ac standard, the main technical parameters of broadband multi-antenna WLAN RF front-end are analyzed, such as operation bandwidth, front-end structure and noise figure. The specific technical parameters of TX/RX channel are put forward.Secondly, according to functionality requirements, the RF front-end has divided into submodules. The front-end uses same eight-way transceiver channel. The structure of TX/RX links and LO links and main technical indexs are discussed. According to the spurious demand of links, the technical parameters of dielectric filter are proposed.Again, the detailed design of the RF front-end based on overall design is worked out. According to requirements, the components are chosen. The budget of link gain, linearity and spurious suppression are analyzed. The main functions need to be designed, such as calibration link switch, LO and gain control. Then the key devices should be designed optimally, such as mixer, LNA, power amplifier, etc.Finally, the RF front-end has been assembled and debugged. Then it was tested in main functions and performances aspect. Through the testing validation, the RF front-end has functions of 665 MHz broadband signal transmit-receive, channel selection and channel calibration. The performance results include 4.1dB receiving noise figure, 29 dBm saturation power, and 70 dBc image rejection.This RF front-end, which covering full band in the 802.11 ac standard, using 8×8 MIMO architecture and supporting channel and spatial stream configuration flexibly, can be used as a hardware platform for validation of next generation WLAN technology. It also promotes a further development of WLAN technology.