128 127 126 125 in this embodiment correspond to the positions i e parking spaces a b c d respectively while other network nodes correspond to other positions e g walkway in the parking lot in this space 1 it should be noted that in addition to the transmitting receiving interface each of the network nodes may further comprise a sensor not shown for sensing usage status of the corresponding position or an indicator not shown for indicating and or broadcasting a traveling direction which will be described in detail hereinafter the processing apparatus 13 comprises a receiving transmitting interface 131 a processor 132 and a storage apparatus 133 first operations of the wireless sensor network system to decide a traveling direction towards an available position a parking space in the space 1 i e a parking guide operation are described please refer to both fig1 a and fig1 b the transmitting receiving interface of a first network node 121 in the network apparatus 12 transmits a trigger signal 102 continuously hence when the mobile apparatus 11 approaches the entrance of the parking lot the mobile apparatus 11 will be triggered by the trigger signal 102 once being triggered the mobile apparatus 11 transmits a starting signal 101 which will be received by the transmitting.