This paper presents the concept, principles, and analysis of maximum ratio transmission for wireless communications where multiple antennas are used for both transmission and reception. The principles and analysis are applicable to general cases, including maximum ratio combining. Simulation results agree with the analysis. The analysis shows that the average overall SNR is proportional to the cross-correlation between channel vectors and that error probability decreases inversely with the (L/spl times/K)th power of the average SNR.

Maximum ratio transmission

In a data communication system capable of variable rate transmission, high rate packet data transmission improves utilization of the forward link and decreases the transmission delay. Data transmission on the forward link is time multiplexed and the base station transmits at the highest data rate supported by the forward link at each time slot to one mobile station. The data rate is determined by the largest C/I measurement of the forward link signals as measured at the mobile station. Upon determination of a data packet received in error, the mobile station transmits a NACK message back to the base station. The NACK message results in retransmission of the data packet received in error. The data packets can be transmitted out of sequence by the use of sequence number to identify each data unit within the data packets.

Method and apparatus for high-rate packet data transmission

A method and apparatus for allocating subcarriers in an orthogonal frequency division multiple access (OFDMA) system is described. In one embodiment, the method comprises allocating at least one diversity cluster of subcarriers to a first subscriber and allocating at least one coherence cluster to a second subscriber.

Ofdma with adaptive subcarrier-cluster configuration and selective loading

A subscriber unit for use in a multiple access spread-spectrum communication system includes a spread spectrum radio interface, responsive to a rate function signal from a base station, and first and second despreaders. The base station assigns the rate function spread-spectrum message channels and the first despreader recovers and modifies an information signal one of the spread spectrum message channels. The information channel mode is then modified for processing by the second despreader, with the second despreader supporting a different information signal rate. The subscriber unit has a capability of communicating with a dynamically changing a transmission rate of an information signal which includes multiple spread spectrum message channels. The system includes a closed loop power control system for maintaining a minimum system transmit power level for a radio carrier station and the subscriber units, and system capacity management for maintaining a maximum number of active subscriber units for improved system performance.

Code division multiple access (CDMA) communication system

Described herein are power receptacle wireless access point (AP) devices that may be used as part of a networked (smart) living and work space. These power receptacle wireless AP devices may be wall-mounted and/or retrofitted over existing electrical outlets or light switches, for providing wireless access to a room or region of a room. The power receptacle wireless AP device may connect via power line communication to a data connection.

Power receptacle wireless access point devices for networked living and work spaces

The present invention relates to an apparatus for providing a digital radio link between at least one fixed unit and at least one mobile unit wherein the apparatus comprises a small number of Rake fingers, one or more of which is assigned at any given to perform a searching operation. Whenever a searching Rake finger or fingers finds a path with higher energy than the current lowest Rake finger, the roles of the Rake finger are exchanged.

Apparatus for use in equipment providing a digital radio link between a fixed and a mobile radio unit

Conventional Rake receivers for spread spectrum signals are typically restricted in the number of multipath components they can usefully combine. The present invention provides apparatus for combining all the useful multipath components in a received signal with modest complexity. Digital correlators are provided over the multipath delay spread of the signal at predetermined intervals and their outputs are maximal ratio combined. With close to rectangular transmission received filters, almost all the entire signal energy can be recovered at the output of the combiner even though no attempt is made to accurately align any of the correlators onto a specific multipath component.

Rake receiver combining all the useful multipath components of a spread spectrum signal

A frequency hopped cellular mobile radio system, comprising a plurality of base stations each affording a cellular region, or cell, within which communication is facilitated with a plurality of mobile units, each of which mobile units is free to move from cell to cell, the system having in combination the following features; a synchronization system which serves to bring all mobile units within a cell into synchronization, as observed from the base station of that cell, whereby orthogonal frequency hopping between mobile units of the cell is facilitated, frequency hopping between mobile units in different cells being non-orthogonal; an affiliation strategy which tends to constrain each mobile unit to maintain communication with a base station selected in dependence upon received signal strength; mobile unit transmission power control in dependence upon received signal/noise ratio at a base station, whereby transmitted mobile power tends towards the minimum necessary for acceptable communication; a frequency hopping strategy, wherein the number of bits per hop is limited to a few bits per hop, the actual number of hops being chosen having regard to performance and overall framing delay constraints; Nyquist filtering of signals effective to constrain interference between hops both in the time domain and in the frequency domain, hopped dwells being arranged to extend in time beyond a nominal bit transmission period (before and after the period) so as to overlap; differential phase shift keying (DPSK) modulation combined with randomized quadrature phase shift keyed (QPSK) modulation to de-correlate interference between cells; and, a system of error control coding.

Mobile cellular radio systems

A code acquisition circuit for acquiring code synchronization between an n-chip spreading code of a received spread spectrum radio signal and an n-chip local reference code generated by a code generator within a receiver, includes a variable delay means which operates to introduce a delay shift into the said received radio signal. A correlator operates to correlate n-chips of the local reference code with n-samples of the received signal communicated thereto, and generates a correlation signal representative of a result of the correlation. A code acquisition controller operates in combination with the correlation signal to maintain the delay shift for at least one correlation and thereafter to change the delay shift, wherein the delay shift is a fraction of one chip period.

Randomized code acquisition

In a direct sequence spread spectrum code division multiple access receiver using interference cancellation, the signal for cancellation is derived by demodulating the unwanted signals and re-modulating a carrier to create a near replica for subtraction from a delayed version of the total received signal. Errors in the demodulation process degrade the cancellation. The present invention provides an optimal way of using the reliability information in the demodulator decision variable either to turn the cancellor off for unreliable bit decisions or to partially disable the cancellor according to the bit reliabilities.

Threshold cancellation means for use in digital mobile radio networks

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