Abstract: An Orthogonal Frequency Division Multiplexing communication system is provided that schedules a transmission of uplink sounding signals or channel quality feedback signals in sounding intervals, or sounding zones, that are outside of the sub-frames, thereby preserving sub-frame capacity for other overhead and data transmissions.

Abstract: A method and apparatus for optimizing downlink transmission in a wireless communication network (100) includes determining (502) a distance of each of a plurality of remote devices (102-114) from a network node (120) and allocating (506) downlink symbols of a frame (300) for the downlink transmission based on the determined distance of each of the plurality of remote devices. Earlier downlink symbols of the frame are allocated to at least one remote device of the plurality of remote devices positioned more distant from the network node in comparison to at least other remote device positioned less distant from the network node.

Abstract: Embodiments provide a means for securing wireless network communications. A security association can be established between a mobile subscriber device (105) and an access router (125) of a wireless communications network (120), upon successful authentication of the mobile subscriber device (105). The security association can utilize a dynamically-generated IP security (IPsec) symmetric key (175) unique to the mobile subscriber device (105). Subsequent network communications between the mobile subscriber device (105) and the access router (125) can be secured using the IPsec symmetric key (175) to either directly authenticate and encrypt/decrypt or dynamically establish further security associations to authenticate and encrypt/decrypt the subsequent network communications (170). Securing of the network communications (175) can be performed as a substitute for or in addition to existing security measures of the wireless communications network (120).

Abstract: A method and apparatus for optimizing downlink transmission in a wireless communication network (100) includes determining (502) a distance of each of a plurality of remote devices (102-114) from a network node (120) and allocating (506) downlink symbols of a frame (300) for the downlink transmission based on the determined distance of each of the plurality of remote devices. Earlier downlink symbols of the frame are allocated to at least one remote device of the plurality of remote devices positioned more distant from the network node in comparison to at least other remote device positioned less distant from the network node.

Abstract: An Orthogonal Frequency Division Multiplexing communication system is provided that schedules a transmission of uplink sounding signals or channel quality feedback signals in sounding intervals, or sounding zones, that are outside of the sub-frames, thereby preserving sub-frame capacity for other overhead and data transmissions.

Abstract: A method for uplink synchronization, in a wireless communication device, with a base station in a wireless communication system based on Orthogonal Frequency Division Multiple Access (OFDMA) is disclosed. The method comprises selecting (440), by the wireless communication device, at least one ranging slot randomly from ranging slots in at least a transition gap. The wireless communication device further transmits (445) at least one ranging code in the selected at least one ranging slot.

Abstract: An unsynchronized base site (104) transmits a time synchronization request to a communication unit (110). A time synchronization error, or a timing offset, for the unsynchronized base site (104) is then determined and transmitted back to the unsynchronized base site (104) to enable the unsynchronized base site to synchronize itself. The time synchronization error is determined for the unsynchronized base site (104) based on the time difference of arrival of the signals received by the communication unit (110) from the base site (104) and at least one synchronized base site (101), the location of the communication unit (110), the location of the base site (104), and the location of the at least one synchronized base site (101).

Abstract: A frequency reference, a time reference and data may be provided on, and subsequently extracted from, a single information stream. To achieve this a modulator 102 generates the single information stream by modulating the data on the frequency reference and pre-empting the data modulation to modulate the time reference on the frequency reference. This single information stream is then provided on a single bus 106 which is coupled to a plurality of base stations 103-105. The base stations 103-105 each include a demodulator 107-109, which recovers the frequency reference 117, the time reference 118, and/or the data 116, from the single information stream.

Abstract: Data transfer for a time division multiplex (TDM) bus in a communication system that includes a plurality of communication nodes wherein each communication node is allocated at least one time slot of the TDM bus can utilize the following protocol to improve flexibility. When a communication node has an information packet to transmit, it must determine whether it is changing from a first information packet type to a second information packet type message. If a change from transmitting a first information packet type to transmitting a second information packet type is determined, an information type transition message is transmitted via the allocated time slot during a first frame cycle. Upon receiving the information type transition message, at least one other communication node stores the information type transition message.

Abstract: A phase lock loop (700) maintains a freewheeling capability while making phase corrections to a sample clock signal based on a precision timing signal. The phase corrections are dispersed over time such that data reception in uninterrupted so that data integrity is maintained during the phase corrections. The phase lock loop (700) includes a first divider circuit (721) having a divisor n, coupled for dividing the incoming clock signal by n to produce a bit clock signal. A second divider circuit (725) is coupled to the bit clock signal for dividing the bit clock signal to produce the sample clock signal.

Abstract: An addressing apparatus and method may be obtained in a data conveyance network by providing modular circuits with an addressing circuit and incorporating a coupling sense circuit. When a modular circuit is connected into the data conveyance modular network, the coupling sense circuit allows for a assignment token to be passed to the modular circuit such that the modular circuit can determine addresses of time slots which are to be allocated to it. The assignment token is only passed amongst the modular circuits at initial turn on of the data conveyance modular network or when a reset condition occurs which is triggered by a data conveyance controller.

Abstract: A data transfer network for computers is disclosed which combines characteristics of both multi-port memory devices and local area networks. Each computer is coupled to the network via a data terminal. The terminal permits the network to appear to the computers as random access memory. Data written into this RAM by the computers is formatted by the terminals into serial data packets, which are shifted around a serially connected ring or loop of the terminals. The loop connected terminals form the network.

Abstract: An encryption key, required to encrypt and decrypt data according to a predefined algorithm is usually retained in a volatile memory device. Detection of loss of the key or corruption of the key is frequently possible only be means of the encryption circuit itself testing the key. Automated and repetitive testing of encryption keys by means of a processor or a control circuit periodically requesting the encryption circuit to test an encryption key minimizes data loss and system down time due to corrupted or lost keys.