摘要:
An antenna selection technique is used in an RF communincation system in which user modules (UM) communicate with at least one node. The UM's and nodes each have multiple antennae. The combination of each UM and node antenna is evaluated at the UM. Based on at least signal quality, the UM selects its antenna and the best node antenna for use. An alternate antenna is selected if a person is determined to be present in a predetermined area adjacent a UM corresponding to a predetermined RF power level.
摘要:
In a wireless TDMA network a control module (CM) sends a time stamp relative to the beginning of its frame in a synchronization packet allowing each of a plurality of user modules (UM) to maintain synchronization relative to the CM. The CM uses a plurality of directional antennas and transmits the synchronization packets over each antenna over a predetermined number of frames. The UMs use a receive time stamp to identify the beginning of a received synchronization packet. The difference between the time stamps combined with a delay constant is used by the UMs to adjust time synchronization to the CM frame.
摘要:
A hierarchical addressing technique is employed in a packet communications system to enhance flexibility in storing and referencing packet information. This method permits packet message data and certain packet control data to be stored in memory locations without having to be duplicated at a different memory location prior to transmission of the packet. This method is preferably employed in a ring configuration in which a series of packets have addressing mechanisms which points sequentially to each other to form a ring of packets received or to be transmitted.
摘要:
A common communication controller is linked to a plurality of peripheral devices by a network interface bus. Packets containing information is communicated between the controller and the peripherals over the bus which consists of a parallel packet bus and a plurality of control lines utilized to implement a communication protocol which increases the efficiencies of packet communications by the utilization of additional direct command lines between the communications controller and peripherals.
摘要:
An improved network interface architecture for a packet switch provides for the combination of both voice and data in a single switch using a common packet structure. It allows for the dynamic allocation of bandwidth based on system loading. This includes not only bandwidth within the voice or data areas of the frame, but also between the voice and data portions. The network interface (NI) provides a mechanism (the NI-Bus) of passing all packets through the Network Interface or allowing the packet devices to directly transfer packets between one another. The bandwidth allocation can easily be changed because the control and data memories are synchronized to one another. The network interface architecture, according to the invention, allows for the data packets and the control of bandwidth allocation to be controlled by a single switching device. It synchronizes the transfer of the data and the allocation of bus bandwidth. The control of the packet devices can be controlled at a very high bit rate such as, for example, 40 Mbps. It also allows packet devices to directly transfer packets. It allows for easy re-allocation of bandwidth through the use of the NI Base Registers.
摘要:
An improved network interface architecture for a packet switch provides for the combination of both voice and data in a single switch using a common packet structure. It allows for the dynamic allocation of bandwidth based on system loading. This includes not only bandwidth within the voice or data areas of the frame, but also between the voice and data portions. The network interface (NI) provides a method (the NI-Bus) or passing all packets through the Network Interface or allowing the packet devices to directly transfer packets between one another. The bandwidth allocation can easily be changed because the control and data memories are synchronized to one another. The network interface architecture, according to the invention, allows for the data packets and the control of bandwidth allocation to be controlled by a single switching device. It synchronizes the transfer of the data and the allocation of bus bandwidth. The control of the packet devices can be controlled at a very high bit rate such as, for example, 40 Mbps. It also allows packet devices to directly transfer packets. It allows for easy re-allocation of bandwidth through the use of the NI Base Registers.
摘要:
An improved network interface architecture for a packet switch provides a mechanism for handling voice and data packets. Bandwidth allocation can be changed because control and data memories are synchronized to one another. A hierarchical addressing technique is employed to enhance flexibility in handling packet information. This method permits packet message data and certain packet control data to be stored in memory locations without having to be duplicated at a different memory location prior to transmission of the packet. In an exemplary wireless TDMA packet network a control module (CM) sends a time stamp relative to the beginning of its frame in a synchronization packet allowing each of a plurality of user modules (UM) to maintain synchronization relative to the CM. The CM uses a plurality of directional antennas and transmits the synchronization packets over each antenna over a predetermined number of frames. The UMs use a receive time stamp to identify the beginning of a received synchronization packet. The difference between the time stamps combined with a delay constant is used by the UMs to adjust time synchronization to the CM frame. Packets are communicated between the controller and the peripherals at the UM and CM over a bus using a communication protocol which increases the efficiencies of packet communications by allowing additional direct command lines between the communications controller and peripherals.
摘要:
A method and apparatus for performing the asynchronous reconstruction of a digital data stream is disclosed. An input data stream having an input rate, such as digitized speech, is stored in a circular buffer. Within the buffer, read and write marker positions are determined. Upon subsequent retrieval of the data stream at an output rate, data is taken from the position of the read marker each time data is written to the position of the write marker. Of importance, the read and write marker positions are determined such that they provide a delay greater than the difference between the input rate and the output rate over the length of the buffer. The data stream processing is then modified by ignoring at least some of the data stream when the input rate is faster than the output rate, and repeating at least some of the data stream when the input rate is slower than the output rate. In this manner a method of digitized voice reconstruction without reliance upon network synchronizatin is achieved.
摘要:
An encryption circuit that operates with substantially zero delay. Using programmable keys and polynomials, the encryption algorithm can be constantly changed to thwart any unintended receiving parties from decoding the data. A key (101) and a polynomial (102) are loaded into registers. The key is then loaded into a shift register and shifted through XOR gates (106) at a programmable rate. The other input of the XOR gates come from the result of ANDing (103) a disable signal, the polynomial register (102), and the last stage of the shift register (104). Eight bits of the shift register outputs are XOR'ed with the input data to be encrypted. The output of these XOR gates (105) is the encrypted data.
摘要:
A radio communications system (10) having a mobile station (30) and at least two base stations (13, 14). ATM radio channels (31, 32) are provided between the remote station and the base stations. Each of the ATM channels supports communication though ATM cells over a common frequency band. When handoff conditions are met for a handoff from the first base station to the second base station, a second virtual path identifier and a second virtual connection identifier are selected for a connection between the second base station and the remote station.