Abstract: A supporting framework having at least one connector and at least two bars arranged on the connector. The bars are preferably arranged on the connector at the longitudinal end regions thereof. The connection between the bars and connector is achieved by at least one bolt, in particular, by two bolts. The bolt is or the bolts are preferably designed in the form of plug-in bolts, in particular fit bolts. The bolt has or the bolts have preferably a diameter of more than 28 mm that acts in the connection to the connector. The bars are formed from a steel having an upper yield strength of above 490 MPa. The bar height is less than 200 mm. The bars, bolts, and connector are preferably part of a lattice truss of the supporting framework, wherein the lattice truss has a lattice truss height of at least 2100 mm.

Abstract: Use of a training sequence having terms that are orthogonal to each other are employed to considerably speed up execution of the LMS algorithm. Such orthogonal sequences are developed for a channel that is described as a finite impulse response (FIR) filter having a length Mnew from the already existing orthogonal training sequences for at least two channels that have respective lengths Mold1 and Mold2 each that is less than Mnew such that the product of Mold1 and Mold2 is equal to Mnew when Mold1 and Mo1d2 have no common prime number factor. More specifically, a set of initial existing orthogonal training sequences is found, e.g., using those that were known in the prior art or by performing a computer search over known symbol constellations given a channel of length M.

Abstract: A channel sounding system employs orthogonal sequences to meet the Cramer-Rao bound in estimating the channel and achieves considerable simplification of the structure necessary to perform the channel sounding. These advantages are achieved by developing orthogonal sequences of substantially arbitrary length as a function of first and second existing orthogonal sequences and using such orthogonal sequences for channel sounding in lieu of M-sequences. The techniques of the invention are especially suited to systems that use multiple antennas at the transmitter and multiple antennas at the receiver, so called multiple-input multiple-output (MIMO) systems.

Abstract: Orthogonal sequences can be developed and used for use training and synchronizing in CDMA and TDMA systems. In particular, once a sequence is developed that has the length of the product of the channel length and the number of transmit antennas, the sequence is offset by a different amount for each transmit antenna. For example, each sequence could be offset by a multiple of the channel length for each transmit antenna, where the multiple ranges from 0 to N?1, where N is the number of transmit antennas. Furthermore, by not using exactly the same amount of offset shifting for each transmit antenna, e.g., not having each signal offset by the channel length, but keeping the overall total shifting the same, e.g., the average of each shift is the channel length, it is possible to determine at a receiver from which transmit antenna a particular signal originated.

Abstract: Signal processing operations are performed in a digital communication system receiver on a sequence of received symbols, each representing a number of information bits. The symbols correspond to points in a given modulation constellation generated by applying a predetermined rotation, e.g., a 45° rotation, to an otherwise conventional modulation constellation, e.g., a QPSK constellation, a 16-QAM constellation, etc. The use of the rotated constellation allows certain signal processing operations, such as filtering, Least-Mean-Squares (LMS) estimation, and Maximum-Likelihood (ML) sequence detection via the Viterbi algorithm, to be performed without the need for multipliers. By eliminating or substantially reducing the number of required multiplication operations, the invention significantly reduces the complexity and delay associated with the corresponding signal processing circuitry.

Abstract: In a TDMA system a multifunction control channel is employed that carries data used for implementing channel access functionality for users and is also employed at the remote terminals in the performance of modem functionality. In other words, information necessary to accurately receive data on the user traffic channels is obtainable by processing the multifunction control channel. This is achieved by arranging the broadband channel of the TDMA system as a repeating frame having time slots in which at least one time slot is reserved for use as the multifunction control channel, and the data that is transmitted on the multifunction control channel is encoded using a spread spectrum format. To this end the data carried on the multifunction control channel is encoded in a way that uses each symbol of the multifunction control channel as if it were a so-called spread spectrum “chip”.

Abstract: In a wireless communication system, the constellation mapping scheme employed may be changed on a per-time-slot basis, i.e., from time slot to time slot, so that the constellation used to encode the symbols of each time slot may be different for each time slot within a single frame and may be different for a particular time slot in different consecutive frames. In other words, several constellation mapping schemes are available, with each providing the ability to transmit a different number of bits per symbol, and the particular constellation mapping scheme employed for any time slot need be selected for that time slot only. The ability to use any particular constellation mapping scheme is dependent on the current channel quality. The particular constellation mapping used for the user data of the time slot may be indicated in the preamble of the time slot.

Abstract: In a system in which the modulation scheme employed may change on a per-time-slot basis, a user's available data rate may change even if the user maintains the same number of time slots, because the capacity of the user's time slots may change. If one or more such changes in modulation scheme occurs, the data rate available to the user may no longer match his current data rate needs. Therefore, a method is disclosed for determining the number of time slots to assign to a user as a function of the user's current data rate requirement and the actual current cumulative data rate of the time slots currently assigned to the user. The user data rate requirement may further be a function of a quality of service (QoS) contracted for by the user.

Abstract: A two layered segmentation technique coupled with a two layer error detection technique is used to implement the wired to wireless network interface. A wireless network divides network layer packets from a wired network into radio data link packets, and the information within the radio data link packets is divided into portions that can be placed into time slots. Error detection is performed on each of the time slots and also at the radio data link packet level to determine if there is an error within the radio data link packet. Errors detected in any radio data link packet only requires retransmission of the radio data link packet in which the error was detected, and, advantageously, do not require retransmission of the entire network layer packet as would have been required in a system that mapped directly from network layer packets to time slots.

Abstract: In the method of pulse shaping according to the present invention, a set of bits representing a symbol is received, and an output value is generated by adding or subtracting a received coefficient and a received value based on a first predetermined one of the set of bits. The generated output value is then supplied as either a real or imaginary output value based on at least a second predetermined one of the set of bits.

Abstract: In a wireless communication system, the constellation mapping scheme employed may be changed on a per-time-slot basis, i.e., from time slot to time slot, so that the constellation used to encode the symbols of each time slot may be different for each time slot within a single frame and may be different for a particular time slot in different consecutive frames. In other words, several constellation mapping schemes are available, with each providing the ability to transmit a different number of bits per symbol, and the particular constellation mapping scheme employed for any time slot need be selected for that time slot only. The ability to use any particular constellation mapping scheme is dependent on the current channel quality. The particular constellation mapping used for the user data of the time slot may be indicated in the preamble of the time slot.

Abstract: A channel sounding system employs orthogonal sequences to meet the Cramer-Rao bound in estimating the channel and achieves considerable simplification of the structure necessary to perform the channel sounding. These advantages are achieved by developing orthogonal sequences of substantially arbitrary length as a function of first and second existing orthogonal sequences and using such orthogonal sequences for channel sounding in lieu of M-sequences. The techniques of the invention are especially suited to systems that use multiple antennas at the transmitter and multiple antennas at the receiver, so called multiple-input multiple-output (MIMO) systems.

Abstract: Estimates of both the communication channel impulse response coefficients and a received signal carrier frequency offset are generated simultaneously without either estimation interfering with or hampering of the other estimation. This is realized in an embodiment of the invention by utilizing both received symbols known to the receiver during a training sequence and a received signal to generate simultaneously an estimate of the impulse response coefficients of the communication channel and an estimate of the received signal carrier frequency offset. In one embodiment of the invention a first estimator and a second estimator are employed to generate the communication channel impulse response coefficients and the received signal carrier frequency offset, respectively.

Abstract: A method and apparatus for equalizing a signal to accurately deconvolute the channel includes deriving a functional relationship between Doppler frequency and variance between the instantaneous energy of the received signal and the mean energy of the received signal. Theoretical values of Doppler frequency for a range of values of variance are mapped based on the derived functional relationship. The variance of a received signal is determined and the corresponding Doppler frequency estimate selected from the map. Optimal equalization learning parameters are then selected based on the corresponding Doppler frequency estimate so that the received signal may be deconvoluted independent of the impact of Doppler frequency.

Abstract: In a system in which the modulation scheme employed may change on a per-time-slot basis, a user's available data rate may change even if the user maintains the same number of time slots, because the capacity of the user's time slots may change. If one or more such changes in modulation scheme occurs, the data rate available to the user may no longer match his current data rate needs. Therefore, a method is disclosed for determining the number of time slots to assign to a user as a function of the user's current data rate requirement and the actual current cumulative data rate of the time slots currently assigned to the user. The user data rate requirement may further be a function of a quality of service (QoS) contracted for by the user.

Abstract: An effective receiver is achieved for situations where the receiver is mobile, and may be traveling at relatively high speed, and where the receiver's internal demodulation oscillator causes a frequency offset, with processing that shares a common algorithm for both frequency offset and channel characteristics estimations. Specifically, the commonly employed algorithm, such as the LMS algorithm, computes an estimate of the frequency offset, and that very same algorithm is also used to estimate the channel characteristics. When the LMS algorithm is used, a frequency offset estimate can be derived from signals derived in the course of executing the LMS algorithm. A frequency compensation factor is then developed and applied to the incoming signal to create a signal that that not have an appreciable frequency offset.

Abstract: A wireless communication terminal comprises a first housing section including an antenna for enabling wireless communications with the terminal and a second housing section including a second communications antenna, the second housing section being extendibly connected to the first housing in an manner such that when the second housing section is in its extended position the second antenna is located one half wavelength from the first antenna. One or both of the antennas may be a fixed type, e.g., a whip or stub, or a retractable type, e.g., telescoping. The antennas may be located external or may be internal (e.g., patch type antennas) to the housing sections.