Abstract: An electronic shelf label system comprises an access point having a first communication module, wherein the first communication module transmits downlink data and receives uplink data wirelessly in a first frequency; a plurality of electronic shelf labels, each having a second communication module, wherein the second communication module receives the downlink data and transmits the uplink data wirelessly in a second frequency; a portable terminal having a third communication module and a scanning module, wherein the scanning module scan an ID information of a product and an ID information of an electronic shelf label, and wherein the third communication module transmits a link information between the product and the electronic shelf label to the access point in the first frequency; and a service daemon, wherein the service daemon receives the uplink data from the access point in a third frequency and receives the link information in the third frequency.

Abstract: A wireless network system utilizing dual frequencies comprises an access point having a first communication module, wherein the first communication module transmits downlink data and receives uplink data wirelessly in a first frequency; a plurality of routers, each having a second communication module, wherein the second communication module receives the downlink data from the access point and transmits the uplink data to the access point wirelessly in the first frequency and transmits the downlink data and receives the uplink data wirelessly in a second frequency; and a plurality of end devices, each having a third communication module, wherein the third communication module receives the downlink data from one of the plurality of routers and transmits the uplink data to the same one of the plurality of routers wirelessly in the second frequency.

Abstract: A method to decrease power consumption of a plurality of end devices in a wireless network system divides a round period into at least a first period and a second period, each of the periods having multiple time slots. The wireless network system is formed by an access point, a plurality of routers and a plurality of end devices, forming a two-layer tree network topology. The method comprising: a) wirelessly broadcasting a null beacon from one of the routers to the router's end devices in the first period if the router fails receive an AP beacon from the access point in the first period; and b) configuring the router's end devices to sleep during the second period after the router's end devices receive the null beacon from the router.