Abstract: A method for evaluating performance of a data communication network with a receiver node arranged to initiate data transmission thereto from a plurality of transmitter nodes directly connected therewith includes applying to the data communication network a stochastic operation model arranged to model operation characteristics of the receiver node, and determining throughput or power consumption of the network based on the stochastic operation model. The operation characteristics include: a duration of a work cycle of the receiver node (Tcycle), the work cycle including an active data communication period (Thold) and an inactive period (Tdwell); a duration of the active data communication period (Thold), the active data communication period including a number of data communication events; the number of data communication events in the work cycle n; a duration of the respective data communication events (Ttx); and amount of data successfully received at the receiver node in the work cycle (Bi).

Abstract: A method for evaluating performance of a data communication network with a receiver node arranged to initiate data transmission thereto from a plurality of transmitter nodes directly connected therewith includes applying to the data communication network a stochastic operation model arranged to model operation characteristics of the receiver node, and determining throughput or power consumption of the network based on the stochastic operation model. The operation characteristics include: a duration of a work cycle of the receiver node (Tcycle), the work cycle including an active data communication period (Thold) and an inactive period (Tdwell); a duration of the active data communication period (Thold), the active data communication period including a number of data communication events; the number of data communication events in the work cycle n; a duration of the respective data communication events (Ttx); and amount of data successfully received at the receiver node in the work cycle (Bi).

Abstract: A MAC protocol, useful for WLANs, is provided for random access over a channel. The protocol includes three concurrent processes. The channel includes a contention subchannel and a transmission subchannel. In the contention process, all nodes use the standard RTS/CTS mechanism operated on the contention subchannel to contend for a transmission right. When one node gains the right, all the nodes store the contention result into their respective contention queue (CQ) buffers. In the transmission process, the nodes sequentially transmit their data over the transmission subchannel according to the order of the nodes stored in the CQ buffers. When one node finishes transmission, the CQ buffers are updated. The contention and transmission processes are connected by the queuing process for dynamically updating each node's CQ buffer. When OFDM is used in a random-access system, numbers of data subcarriers in both subchannels for maximizing the system throughput are given.

Abstract: The throughput of a wireless network can be boosted by network coding (NC). The present invention combines NC-aware routing and TDMA-based MAC protocol for energy-efficient design in the wireless network, and provides a method thereof. An optimization model, which is a minimum energy consumption model (MECM), is formulated for minimizing the energy consumption for accomplishing a set of flow transmissions. In particular, based on a set of user traffic-flow demands, a NC-aware traffic-flow assignment that minimizes a total energy consumption of packets delivering to meet the user traffic-flow demands is determined. Thereafter, given the optimal flow assignment, a minimum timeslots model (MTM) which leads to a TDMA-based scheduling strategy at the MAC layer is developed. The MTM is to minimize the total number of timeslots required for transmission under a condition that the NC-aware traffic-flow assignment as already determined is accomplishable.

Abstract: A MAC protocol, useful for wireless local area networks (WLANs), is provided for improving throughput efficiency. The protocol includes three concurrent processes, and the channel is divided into a contention subchannel and a transmission subchannel. In the contention process, all nodes use the standard RTS/CTS mechanism operated on the contention channel to contend for a right of transmission. When one node gains the right, all the nodes store the contention result into their respective contention queue (CQ) buffers. In the transmission process, the nodes sequentially transmit their data over the transmission channel according to the order of the nodes stored in the CQ buffers. When one node finishes data transmission, the CQ buffers are updated. The contention process and the transmission process are connected by the queuing process, where each node dynamically updates its own CQ buffer according to the contention result and each instance of data transmission.

Abstract: A method for optimizing throughput of a network with stations adapted to transmit data to an access point includes the step of determining a respective required throughput for each station based on: respective time periods required for decreasing a count of a respective back-off counter associated with each of the stations, a transmission packet length of the respective station, and a probability of successful transmission for of the respective station. The respective required throughput so determined is a function of a respective transmission attempt rate for the station. The method further includes the step of determining the respective transmission attempt rate for each station for maximizing a sum of the respective required throughput such that a respective fixed throughput is provided for inelastic data flow in the network, a respective proportional throughput ratio is provided for elastic data flow in the network, and the throughput of the network is maximized.

Abstract: The present invention provides a method of power control for a plurality of secondary users (SUs), or unlicensed users, in a cognitive radio network having a plurality of primary users (PUs), or licensed users. The method comprises determining an optimal power level for each of the SUs such that a total throughput of all the SUs is maximized while satisfying an individual throughput requirement of each SU and an interference limit constraint of the PUs. In particular, a case having two SUs is considered.

Abstract: A communication system and a method for transmitting data over a communication network includes a processing module arranged for selectively splitting a traffic demand of a transmission link into a plurality of portions of traffic demands distributed over a main channel and at least one auxiliary channel of the communication network, and the processing module is further arranged to determine a data transmission relationship associated with the traffic demand of the transmission link and at least one parameter of both the main channel and the at least one auxiliary channel; and a transmission module arranged to transmit data over one or more of the main channel and the at least one auxiliary channel according to the data transmission relationship.

Abstract: A method for optimizing throughput of a network with stations adapted to transmit data to an access point includes the step of determining a respective required throughput for each station based on: respective time periods required for decreasing a count of a respective back-off counter associated with each of the stations, a transmission packet length of the respective station, and a probability of successful transmission for of the respective station. The respective required throughput so determined is a function of a respective transmission attempt rate for the station. The method further includes the step of determining the respective transmission attempt rate for each station for maximizing a sum of the respective required throughput such that a respective fixed throughput is provided for inelastic data flow in the network, a respective proportional throughput ratio is provided for elastic data flow in the network, and the throughput of the network is maximized.

Abstract: The throughput of a wireless network can be boosted by network coding (NC). The present invention combines NC-aware routing and TDMA-based MAC protocol for energy-efficient design in the wireless network, and provides a method thereof. An optimization model, which is a minimum energy consumption model (MECM), is formulated for minimizing the energy consumption for accomplishing a set of flow transmissions. In particular, based on a set of user traffic-flow demands, a NC-aware traffic-flow assignment that minimizes a total energy consumption of packets delivering to meet the user traffic-flow demands is determined. Thereafter, given the optimal flow assignment, a minimum timeslots model (MTM) which leads to a TDMA-based scheduling strategy at the MAC layer is developed. The MTM is to minimize the total number of timeslots required for transmission under a condition that the NC-aware traffic-flow assignment as already determined is accomplishable.

Abstract: The present invention provides a method of power control for a plurality of secondary users (SUs), or unlicensed users, in a cognitive radio network having a plurality of primary users (PUs), or licensed users. The method comprises determining an optimal power level for each of the SUs such that a total throughput of all the SUs is maximized while satisfying an individual throughput requirement of each SU and an interference limit constraint of the PUs. In particular, a case having two SUs is considered.

Abstract: A MAC protocol, useful for WLANs, is provided for random access over a channel. The protocol includes three concurrent processes. The channel includes a contention subchannel and a transmission subchannel. In the contention process, all nodes use the standard RTS/CTS mechanism operated on the contention subchannel to contend for a transmission right. When one node gains the right, all the nodes store the contention result into their respective contention queue (CQ) buffers. In the transmission process, the nodes sequentially transmit their data over the transmission subchannel according to the order of the nodes stored in the CQ buffers. When one node finishes transmission, the CQ buffers are updated. The contention and transmission processes are connected by the queuing process for dynamically updating each node's CQ buffer. When OFDM is used in a random-access system, numbers of data subcarriers in both subchannels for maximizing the system throughput are given.

Abstract: A MAC protocol, useful for wireless local area networks (WLANs), is provided for improving throughput efficiency. The protocol includes three concurrent processes, and the channel is divided into a contention subchannel and a transmission subchannel. In the contention process, all nodes use the standard RTS/CTS mechanism operated on the contention channel to contend for a right of transmission. When one node gains the right, all the nodes store the contention result into their respective contention queue (CQ) buffers. In the transmission process, the nodes sequentially transmit their data over the transmission channel according to the order of the nodes stored in the CQ buffers. When one node finishes data transmission, the CQ buffers are updated. The contention process and the transmission process are connected by the queuing process, where each node dynamically updates its own CQ buffer according to the contention result and each instance of data transmission.

Abstract: A method for scheduling a random-access communication system having high-priority (HP) and low-priority (LP) nodes is provided, where the scheduling is configured such that the system provides an absolute throughput guarantee for the HP nodes, and a proportional throughput guarantee for the LP nodes. The method is based on obtaining a length of a contention window assigned to an individual node, which is either a HP or a LP node, from a per-slot attempt rate of this individual node. In particular, the attempt rate of each individual node is determined by an algorithm configured such that a resultant sum of the per-slot attempt rates of all the individual nodes is a fixed value independent of the number of the individual nodes. By this scheduling method, the maximum system throughput is approached. The method can be advantageously used in a wireless local area network (WLAN).

Abstract: The present invention provides a method for updating a mobile terminal (MT) for a mobile communication network when the MT crosses a boundary of a first location-update (LA) area. The method comprises determining a second LA to be assigned to the MT for replacing the first LA. The second LA is characterized by a LA center and a LA size, both determined by optimizing them in a sense that a mean total location-management cost is minimized without restricting the LA center to be fixed at the initial position. The initial position is defined as the location where the MT performs a latest location update at the first LA before crossing the boundary. This invention also provides schemes of partitioning the second LA into sub-paging areas for use in paging the MT when a call arrives at the network, so as to minimize the paging cost while satisfying delay requirements.

Abstract: A method for scheduling a random-access communication system having high-priority (HP) and low-priority (LP) nodes is provided, where the scheduling is configured such that the system provides an absolute throughput guarantee for the HP nodes, and a proportional throughput guarantee for the LP nodes. The method is based on obtaining a length of a contention window assigned to an individual node, which is either a HP or a LP node, from a per-slot attempt rate of this individual node. In particular, the attempt rate of each individual node is determined by an algorithm configured such that a resultant sum of the per-slot attempt rates of all the individual nodes is a fixed value independent of the number of the individual nodes. By this scheduling method, the maximum system throughput is approached. The method can be advantageously used in a wireless local area network (WLAN).

Abstract: A power supply device for providing an output voltage includes a first resonant converter, a second resonant converter, a first converting circuit, and a current regulating circuit. The first resonant converter is for converting a first input voltage into the output voltage. The second resonant converter is for converting a second input voltage into the output voltage. The output ends of the first and second resonant converters are coupled in parallel. The first converting circuit is coupled to the first resonant converter and is operable to provide the first input voltage to the first resonant converter. The current regulating circuit receives signals related to output currents of the first and second resonant converters, and drives operation of the first converting circuit according to the signals received thereby such that the output currents of the first and second resonant converters have substantially equal magnitudes.

Abstract: A frequency-hopping control method is performed by a frequency-hopping control module that generates a driving signal for driving a voltage converting circuit to generate an output voltage. The method includes, generating a control signal according to a regulating signal inversely proportional to the output voltage of the voltage converting circuit. The control signal is cyclical, and each cycle of which includes an off-time having a variable duration with an inverse relation to magnitude of the regulating signal, and an on-time having a substantially fixed duration. The driving signal is generated according to the control signal and a periodic pulse signal. Therefore, the output voltage can be stabilized, and the voltage converting circuit can perform voltage conversion with reduced power loss and improved voltage conversion efficiency.

Abstract: A power supply device includes first and second power factor correctors, and first and second resonant circuits. The first and second power factor correctors are for receiving an alternating current (AC) input voltage, and are driven by first and second driving signals for rectifying the AC input voltage to generate first and second driving voltages, respectively. The first and second resonant circuits are coupled to the first and second power factor correctors for receiving the first and second driving voltages, respectively, and have output sides that are coupled in parallel for outputting an output voltage. The first power factor corrector and the first resonant circuit in combination is parallel-connected to the second power factor corrector and the second resonant circuit in combination.

Abstract: A controller is adapted for controlling a switch of a resonant direct current/direct current converter, and includes: a pulse width modulation controlling unit for detecting an output voltage of the resonant direct current/direct current converter, and for generating a pulse width modulation signal according to the output voltage detected thereby; a fixed frequency signal generating unit for generating a fixed frequency signal; and a logic synthesizing unit for synthesizing the pulse width modulation signal and the fixed frequency signal so as to generate a driving signal that is adapted to drive the switch of the resonant direct current/direct current converter.