Abstract: A method and apparatus for admission control in a wireless train communication system with TDMA are disclosed. The method and apparatus according to one embodiment of the present invention identifies neighboring devices within neighborhood of a given device that use the time slot. The frequency and location information for the intended device and the unintended devices are used to determine whether to grant the time slot. In another embodiment according to the present invention, the receive signal strength information at the neighboring devices is used, instead of the distance information, for admission control.

Abstract: A system and method of frequency offset compensation are disclosed for a wireless system between a fast moving radio terminal associated with a locomotive and a stationary radio terminal associated with a base station. The present invention utilizes advanced frequency offset prediction to quickly track Doppler Shift caused by a fast moving locomotive. In one embodiment according to the present invention, the frequency offset prediction is based on a first plurality of coarse frequency offsets, first-order derivatives of the first plurality of coarse frequency offsets, and second-order derivatives of the first plurality of coarse frequency offsets. In another embodiment according to the present invention, the frequency offset prediction is based on a plurality of previous frequency offsets according to a Doppler shift model.

Abstract: A configurable antenna arrangement is disclosed for wireless Positive Train Control system to overcome the deep fading and fast fading issue. The radio channel between a locomotive on-board radio unit and a base station is subject to fast and deep fading. The channel changes rapidly in a short time comparing to the length of the packet. The invention uses a TX antenna and a RX antenna in a time division multiple access (TDMA) radio system associated with control circuits to provide a configurable antenna sub-system. The antenna sub-system is configurable to provide a TX mode, a primary RX mode and a secondary RX mode. In both the TX mode and the primary RX mode, there is substantially no insertion loss. In the secondary RX mode, the TX antenna is used as the secondary RX antenna to overcome fading caused by Doppler shift.

Abstract: A system and method of frequency offset compensation are disclosed for a wireless system between a fast moving radio terminal associated with a locomotive and a stationary radio terminal associated with a base station. The present invention utilizes advanced frequency offset prediction to quickly track Doppler Shift caused by a fast moving locomotive. In one embodiment according to the present invention, the frequency offset prediction is based on a first plurality of coarse frequency offsets, first-order derivatives of the first plurality of coarse frequency offsets, and second-order derivatives of the first plurality of coarse frequency offsets. In another embodiment according to the present invention, the frequency offset prediction is based on a plurality of previous frequency offsets according to a Doppler shift model.

Abstract: Devices, systems and related methods are disclosed for improving operational security of a network and/or network devices, such as wireless access points (APs). In the disclosed systems, a network device is not fully operational until it is attached to a network and downloads sensitive information. The information is stored in the network device so that when the device is disconnected from the network, the sensitive information is erased from the device, making the device inoperative and removing sensitive information, such as passwords, network security keys, or the like. Disabling the network device in this manner not only prevents the theft of sensitive network access information, by also discourages theft of the device itself because it cannot be used on another network without the configuration information. In addition to downloading configuration information, the network device can also download an executable image that is likewise not permanently resident on the device.

Abstract: A network switch having a unified, adaptive management paradigm for wireless network devices is disclosed. The switch includes configurable ports for connecting devices. A software application running on the switch allows a network administrator to selectively configure each port to support either a wired device or wireless device. Configuration information and software images that are needed for operation of the wireless device are associated with the port. When a wireless device is first plugged into the switch port, it downloads its configuration directly from the switch port. By storing the configuration information and images at the switch and automatically downloading them to the wireless devices, the task of configuring the devices is greatly simplified for the network administrator. This is particularly advantageous in heterogeneous network environments that support both wired and wireless devices, and where wireless device are readily moved to different ports.

Abstract: A wireless communication system is structured to a have a first branch and a second branch. The first branch is configured for communications between a wireless terminal and a telecommunication device coupled to a PSTN. The second branch is configured for data communications between the wireless terminal and a host server coupled to the Internet. The second branch includes a PDSN coupled to receive data signals from the wireless terminal and to send data signals to the wireless terminal, a router coupled to the Internet, and a server coupled between the router and the PDSN. The server is configured to translate a first transmission protocol used for communications over the Internet to a second transmission protocol used for communications with the wireless terminal.