Backscatter communications will play an important role in connecting everything for beyond 5G (B5G) and 6G systems. One open challenge for backscatter communications is that the signals suffer a round-trip path loss so that the communication distance is short. In this paper, we first calculate the communication distance upper bounds for both uplink and downlink by measuring the tag sensitivity and reflection coefficient. It is found that the activation voltage of the envelope detection diode of the downlink tag is the main factor limiting the backscatter communication distance. Based on this analysis, we then propose to implement a low-noise amplifier (LNA) module before the envelope detection at the tag to enhance the incident signal strength. Our experimental results on the hardware platform show that our method can increase the downlink communication range by nearly 20 m.

With the increasing popularity and rising demand for high - rate wireless Internet access , traditional wireless access networks such as cellular network and Wireless Local Area Network (WLAN) are facing some challenges . The Wireless Mesh Network (WMN) is emerging as a flexible and low- cost alternative to provide multi- hop communications , supporting applications such as last- mile Internet delivery. The WMN has also become a promising technology in the merging of wireless networks . Some key technologies for the WMN networking , including network configuration , power control, mobility management, access control, and routing protocols , are analyzed ; the routing protocol design in WMN and mobile Ad hoc network are compared . An example of WMN testbed based on WLAN and second - layer switching technology is given .