In this paper a new active RFID system at 2.45 GHz based on the low-power system-on-chip CC2530 RF transceiver is designed and implemented. Only by using of an integrated multi-channel fast chip, both the MCU and RF o...In this paper a new active RFID system at 2.45 GHz based on the low-power system-on-chip CC2530 RF transceiver is designed and implemented. Only by using of an integrated multi-channel fast chip, both the MCU and RF operations are done which makes the RFID more reliable and reduces the complexity of the hardware and cost, vividly. This RFID system utilizes the Zig-Bee IEEE 802.15.4 standard in the ISM band. A lot amount of energy is restored by setting Tags in the sleep mode in the most of times. The maximum transmission range of 80 m at the output power of 4.5 dBm is obtained. The main application of this system is for the container identification with precise operation and high accuracy. An active Tag with unique ID is mounted on each vehicle. By enabling the AUTOCRC error detection possibility, minor errors are detected in the received frames. Receiver sensitivity of –97 dBm and current consumption of 1 μA in the sleep mode and 29.6 mA in the active mode are reported.展开更多
Vehicular ad hoc networks （VANETs） that use the IEEE 802.11p communication standard face a number of challenges, not least when it comes to safety messages on the VANET control channel （CCH） where short delay time...Vehicular ad hoc networks （VANETs） that use the IEEE 802.11p communication standard face a number of challenges, not least when it comes to safety messages on the VANET control channel （CCH） where short delay times and reliable delivery are of pri- mary importance. In this paper we propose a vehicular machine-to-machine （VM2M） overlay network that uses Long Term Evolu- tion （LTE） physical random access channel （PRACH） to emulate VANET CCH. The overlay network uses dedicated preambles to separate vehicular traffic from regular LTE traffic and a cartier sense multiple access with collision avoidance （CSMA-CA） layer similar to the one used in IEEE 802.15.4 to avoid the four step handshake and the overhead it incurs. The performance of the pro- posed overlay is evaluated under a wide range of PRACH parameters which conform to the scenarios with high vehicle velocities and large distances between roadside units （RSUs） that may be encountered in rural areas and on highways.展开更多
The IEEE 802.15.4 standard utilizes the CSMA-CA mechanism to control nodes’ access to the shared wireless communication medium. CSMA-CA implements the Binary Exponential Backoff (BEB) algorithm by which a node refrai...The IEEE 802.15.4 standard utilizes the CSMA-CA mechanism to control nodes’ access to the shared wireless communication medium. CSMA-CA implements the Binary Exponential Backoff (BEB) algorithm by which a node refrains from sending any packet before the expiry of its backoff period. After that, the node is required to sense the medium for two successive time slots to assert that the medium is clear from any ongoing transmissions (this is referred to as Clear Channel Assessment (CCA)). Upon finding the medium busy, the node doubles its backoff period and repeats that process. While effective in reducing the likelihood of collisions, this approach takes no measures to preserve the priorities among the nodes contending to access the medium. In this paper we propose the Priority-Based BEB (PB-BEB) algorithm in which we enhance BEB such that nodes’ priority is preserved. We provide a simulation study to examine the performance of PB-BEB. Our simulations show that the latter not only outperforms BEB in terms of fairness, but also show promising results in terms other parameters like channel utilization, reliability, and power conservation.展开更多
文摘In this paper a new active RFID system at 2.45 GHz based on the low-power system-on-chip CC2530 RF transceiver is designed and implemented. Only by using of an integrated multi-channel fast chip, both the MCU and RF operations are done which makes the RFID more reliable and reduces the complexity of the hardware and cost, vividly. This RFID system utilizes the Zig-Bee IEEE 802.15.4 standard in the ISM band. A lot amount of energy is restored by setting Tags in the sleep mode in the most of times. The maximum transmission range of 80 m at the output power of 4.5 dBm is obtained. The main application of this system is for the container identification with precise operation and high accuracy. An active Tag with unique ID is mounted on each vehicle. By enabling the AUTOCRC error detection possibility, minor errors are detected in the received frames. Receiver sensitivity of –97 dBm and current consumption of 1 μA in the sleep mode and 29.6 mA in the active mode are reported.
文摘Vehicular ad hoc networks （VANETs） that use the IEEE 802.11p communication standard face a number of challenges, not least when it comes to safety messages on the VANET control channel （CCH） where short delay times and reliable delivery are of pri- mary importance. In this paper we propose a vehicular machine-to-machine （VM2M） overlay network that uses Long Term Evolu- tion （LTE） physical random access channel （PRACH） to emulate VANET CCH. The overlay network uses dedicated preambles to separate vehicular traffic from regular LTE traffic and a cartier sense multiple access with collision avoidance （CSMA-CA） layer similar to the one used in IEEE 802.15.4 to avoid the four step handshake and the overhead it incurs. The performance of the pro- posed overlay is evaluated under a wide range of PRACH parameters which conform to the scenarios with high vehicle velocities and large distances between roadside units （RSUs） that may be encountered in rural areas and on highways.
文摘The IEEE 802.15.4 standard utilizes the CSMA-CA mechanism to control nodes’ access to the shared wireless communication medium. CSMA-CA implements the Binary Exponential Backoff (BEB) algorithm by which a node refrains from sending any packet before the expiry of its backoff period. After that, the node is required to sense the medium for two successive time slots to assert that the medium is clear from any ongoing transmissions (this is referred to as Clear Channel Assessment (CCA)). Upon finding the medium busy, the node doubles its backoff period and repeats that process. While effective in reducing the likelihood of collisions, this approach takes no measures to preserve the priorities among the nodes contending to access the medium. In this paper we propose the Priority-Based BEB (PB-BEB) algorithm in which we enhance BEB such that nodes’ priority is preserved. We provide a simulation study to examine the performance of PB-BEB. Our simulations show that the latter not only outperforms BEB in terms of fairness, but also show promising results in terms other parameters like channel utilization, reliability, and power conservation.
