Abstract: Spectral shaping for narrowband interference avoidance is an important part in cognitive radio, and is essential in ultra wideband (UWB) communication systems. Typically, interference occurs when a broadband user's signal collides with a narrowband user's signal, thus resulting in degradation in performance for the two communication links. It has been proposed that, in some applications, the broadband user should modify his signal such that little or no energy is transmitted on the frequencies on which the narrowband user's signal resides. This ‘interference avoidance’ (IA) technique provides some separation of users' signals such that, with the possible aid of signal processing, both communication links do not significantly suffer from multi-user interference. The proposed invention provides a means of implementing interference avoidance in a dynamic manner for a modest increase in complexity at the transmitter.

Abstract: This invention relates to methods for data transmission in OFDM (Orthogonal Frequency Division Multiplexed) communication systems. More particularly, it relates to data transmission in multi-band OFDM (MB-OFDM) systems. The method of generating an OFDM signal for transmission, comprises the steps of: dividing a plurality of subcarriers into two or more groups of subcarriers, minimising the peak-average power ratio (PAPR) of an OFDM signal, and enhancing the transmission of said OFDM signal by further repeating transmission of said OFDM signal.

Abstract: Code division multiple access (CDMA) is a popular multiple access technique that is used to support multiple users simultaneously in a network. Many variants of CDMA exist, including direct sequence (DS) CDMA, multi-carrier (MC) CDMA, cyclic prefixed (CP) CDMA, and chip interleaved block spread (CIBS) CDMA. In addition to these variations, many receiver architectures are often available for implementation in CDMA systems, such as the well-known RAKE receiver, interference cancellation receivers, and receivers that rely on channel equalisation. Many MUI-free techniques rely on user separation in the frequency domain by assigning mutually exclusive sets of tones to each user. The known techniques of multiple access, however, do not allow each individual user to fully exploit the frequency diversity in the channel since each user only utilises a portion of the total available bandwidth to transmit a message.

Abstract: Code division multiple access (CDMA) is a popular multiple access technique that is used to support multiple users simultaneously in a network. Many variants of CDMA exist, including direct sequence (DS) CDMA, multi-carrier (MC) CDMA, cyclic prefixed (CP) CDMA, and chip interleaved block spread (CIBS) CDMA. In addition to these variations, many receiver architectures are often available for implementation in CDMA systems, such as the well-known RAKE receiver, interference cancellation receivers, and receivers that rely on channel equalisation. Some CDMA schemes are interference limited; that is to say, as the number of users in the network increases, residual interference caused by each user eventually cripples the network, thus rendering simultaneous multiple access nearly impossible. This residual interference generally results from the loss of orthogonality amongst users, which primarily occurs when the channel is temporally dispersive.

Abstract: An OFDM signal transmitted from an OFDM transmitter, the signal having a payload portion comprising a first number of data symbols and a second number of padding symbols such that the combined number of data symbols and padding symbols equates to an integer number of OFDM symbols and wherein the padding symbols comprise training symbols

Abstract: A method of estimating channel response in a communications system comprising a transmitting device having a plurality of transmit antennas and a receiving device having at least one receive antenna, the method comprising: (a) Superimposing training sequences onto transmit data to be transmitted by the transmit antennas in order to form a composite message, wherein the training sequences for each transmit antenna are arranged such that they are non-overlapping in the frequency domain; (b) Transmitting the composite message from step (a); (c) Receiving data at the receiving device and then performing the following steps across all channels i. Equalising received data to remove channel distortion; ii. detecting an estimate for the transmit data; iii. using the estimate of the transmit data from step (c)(ii) in order to derive an estimate of the received training sequences as modified by the channel response from the received data; iv.