Abstract: A base station receiving uplink data transmitted from mobile terminals of first type and mobile terminals of second type over a radio interface using plural sub-carriers. The mobile terminals of first type transmit uplink data on a first group of the sub-carriers over a first bandwidth and the mobile terminals of second type transmit uplink data on a second group of the sub-carriers within the first group of sub-carriers over a second bandwidth that is smaller than the first bandwidth. The base station is configured to grant uplink radio resources in response to random access request messages transmitted by mobile terminals of first type transmitted on a first random access channel and to grant uplink radio resources in response to random access request messages transmitted by mobile terminals of second type transmitted on a second random access channel, which are transmitted on sub-carriers within the second group of sub-carriers.

Abstract: A mobile communications system for communicating data to and/or from mobile communications devices. The mobile communications system comprises one or more base stations, each of which includes a transmitter and a receiver operable to provide a wireless access interface for communicating data to and/or from the mobile communications devices, the wireless access interface providing on a downlink a host carrier, the host carrier providing a plurality of resource elements across a first frequency range for communicating data; and a first and second mobile communications devices. The wireless access interface provided by the base stations is arranged to provide a virtual carrier, the virtual carrier providing one or more resource elements within a second frequency range which is within and smaller than the first frequency range, and the second mobile communications device is operable, upon detection of the virtual carrier, to receive downlink communications via the virtual carrier.

Abstract: A mobile terminal for use in a mobile communications network includes a wireless access interface that provides a shared communications channel for communicating data to/from the mobile communications network, the shared channel divided in time into units of communications resource.

Abstract: A mobile telecommunications system including mobile terminals of first type and second type configured to transmit uplink data to a network over a radio interface using plural sub-carriers. The mobile terminals of first type configured to transmit uplink data on a first group of the sub-carriers over a first bandwidth and the mobile terminals of second type configured to transmit uplink data on a second group of the sub-carriers within the first group of sub-carrier over a second bandwidth smaller than the first bandwidth. The mobile terminals of first type transmit random access request messages to a base station of the network requesting uplink radio resources on a first random access channel. The mobile terminals of second type transmit random access request messages to the base station of the network requesting uplink radio resources on a second random access channel on sub-carriers within the second sub-carrier group.

Abstract: A base station communicating data to/from plural mobile terminals over plural OFDM sub-carriers within a coverage area. The base station allocates transmission resources provided by a first group of the plural OFDM sub-carriers within a first frequency band to mobile terminals of a first type and allocates transmission resources provided by a second group of the plural OFDM sub-carriers within a second frequency band to terminals of a second type, the second group being smaller than the first group and the second frequency band selected from within the first frequency band. The base station transmits control information including resource allocation information for terminals of the first type over a first bandwidth corresponding to the combined first and second groups of OFDM sub-carriers and transmits control information including resource allocation information for terminals of the second type over a second bandwidth corresponding to the second group of OFDM sub-carriers.

Abstract: A network element for use in a mobile communications system and a method of using a network element for communicating data to/from mobile communications devices in a mobile communications system. The network element can provide a wireless access interface for communicating data to/from the mobile communications devices, the wireless access interface including: on a downlink a host carrier, the host carrier providing plural resource elements across a first frequency range; transmit data for a first group of mobile communications devices, wherein the data is distributed within the plural resource elements across the first frequency range; a virtual carrier via the wireless access interface, the virtual carrier providing one or more resource elements within a second frequency range which is within and smaller than the first frequency range; and transmit data for a second group of mobile communications devices via the virtual carrier.

Abstract: In a lattice-reduction-aided receiver based wireless communications system, soft estimates of transmitted bit values are determined from a received signal by applying lattice reduction to the channel estimate and equalising the received signal in accordance with the reduced basis channel, and determining probabilities of transmitted bits having particular values by selecting a core candidate vector in the reduced basis, determining a set of mapping functions between the core vector in the reduced basis and transmitted symbol vectors from which a set of candidate transmitted symbol vectors can be generated, generating a set of transmitted symbol vectors based on the mapping functions and, on the basis of the received signal determining the probability of each transmitted bit value having been transmitted.

Abstract: In a lattice-reduction-aided receiver based wireless communications system, soft estimates of transmitted bit values are determined from a received signal by applying lattice reduction to the channel estimate and equalising the received signal in accordance with the reduced basis channel, and determining probabilities of transmitted bits having particular values by generating a set of candidate vectors in the reduced basis based on nearest candidate vectors, determining a corresponding transmitted symbol vector for each candidate vector and, on the basis of the received signal determining the probability of each transmitted bit value having been transmitted.

Abstract: This invention relates to methods, apparatus, and processor control code for signal detection in Multiple Input Multiple Output Orthogonal Frequency Division Multiplexed (MIMO-OFDM) communications systems. A method for determining outputs from a received signal in a lattice-reduction-aided receiver based multi-carrier wireless communications system having a plurality of sub-carriers divided into a plurality of sets of sub-carriers, the method comprising performing a detection method for each of said sets, the detection method comprising the step of applying lattice reduction to said set of sub-carriers thereby generating a reduced basis channel response.

Abstract: In a lattice-reduction-aided receiver based wireless communications system, soft estimates of transmitted bit values are determined from a received signal by applying lattice reduction to the channel estimate and equalising the received signal in accordance with the reduced basis channel, and determining probabilities of transmitted bits having particular values by selecting a set of candidate vectors in the reduced basis, determining a corresponding transmitted symbol vector for each candidate vector and, on the basis of the received signal determining the probability of each transmitted bit value having been transmitted.

Abstract: The present invention relates to estimating and correcting for frequency offset errors in wireless receivers, and is particularly but not exclusively related to MIMO WLAN applications. The present invention provides an improved method of tracking receiver frequency offsets in a receiver for MIMO systems. These receiver based frequency offset components are caused by errors or inaccuracies in various receiver sub-systems such as phase lock loops or carrier frequency oscillator error, and sampling clock rate errors. The frequency offsets due to each of a number of receiver sub-systems are estimated by monitoring frequency offsets on a number of channels or subcarriers (such as OFDM pilot channels) on different frequencies. These channel frequency offsets are preferably estimated by detecting the phase rotation between adjacent pilot symbols on each respective channel. They are then weighted according to a quality parameter of the estimates, which corresponds to their accuracy.

Abstract: An interleaver is described for use in MIMO transmission, for use in a transmitter apparatus for generating a multi-antenna output for transmission into a MIMO channel. The transmission apparatus comprises a data source for generating a block of coded bits for transmission in a first configuration, and the interleaver is operable to permute the bits into a second configuration, and to pass the permuted data to modulating means for modulating the bits in the second configuration into an OFDM frame for transmission. The interleaving means comprises mapping means for applying a mapping function to a first value describing the position of a bit in said first configuration. The mapping means is operable to generate a second value describing the position of the bit in the second position, the relationship between the second value and the first value being based on the product of the first value and a factor co-prime with the number of bits in said block of data.

Abstract: The present invention relates to packet construction of format for communications across multiple access networks such as wireless local area networks (WLAN). The present invention provides a device for use in a wireless network and comprising means for generating a packet comprising a first portion having a destination address and preferably a network duration identifier for a recipient device in the network, and a second portion; and means for transmitting the first portion at a predetermined coding and/or modulation rate, and means for transmitting the second portion at a higher coding and/or modulation rate.

Abstract: The invention relates to apparatus, methods, processor control code and signals for channel estimation in MIMO (Multiple-input Multiple-output) OFDM (Orthogonal Frequency Division Multiplexed) communication systems. An OFDM signal is transmitted from an OFDM transmitter using a plurality of transmit antennas but has one or more nulled subcarriers, corresponding to windowing in the frequency domain. The OFDM signal is adapted for channel estimation for channels associated with said transmit antennas by the inclusion of orthogonal training sequence data in the signal from each said antenna. The training sequence data is derived from substantially orthogonal training sequences for each said transmit antenna, the training sequences being constructed based upon sequences of values Xmk=exp(?j2?km/M) where k indexes a value in a said sequence, m indexes a transmit antenna, and M is the number of transmit antennas.

Abstract: A communications system (101) comprises a transmitting device (102) and a receiving device (114). The transmitting device (102) comprises at least T transmit antennas (116), means for spreading (110) each of T symbols (x) in the time domain only to produce T time sequences of chips (x1, x2, X3=X) and transmitting the T time sequences of chips (X) from the T transmit antennas (116) respectively. The receiving device (114) comprises at least R receive antennas (118), means for despreading (120) the R time sequences of chips (y1, y2, y3=Y) received from the transmitting device (102) at the R receive antennas (118) respectively to a produce R received symbols (z), and means for processing (116-1) the R received symbols (z) to produce an estimate ({circumflex over (x)}) of the T symbols (x) spread at the transmitting device (102).

Abstract: A communications system (201) comprises a transmitting device (202) having a plurality of transmit antennas (206) and a receiving device (214) having a plurality of receive antennas (218). When it is determined that an error has occurred in a first data transmission attempt in which data signals (x) are transmitted from a first selection (S1) of transmit antennas (206) for receipt at a second selection (S2) of receive antennas (218), a second data transmission attempt is performed in which the data signals (x) are re-transmitted from a third selection (S3, not shown) of transmit antennas (206) for receipt at a fourth selection (S4, not shown) of receive antennas (218).

Abstract: A communications system (301) is provided for carrying out spread spectrum communication. In a transmitting device (302) of the communications system 301, a spreading portion (310) spreads an input signal (d) using a spreading code (SC) and a transmitting portion (311, 306) transmits the signal (C) spread by the spreading portion (310). In a receiving device (314), a receiving portion (318, 325) receives the signal (Df) transmitted by the transmitting portion (311, 306), and a despreading portion (320) inversely spreads the signal (D) received by the receiving portion (318, 325) by using an inverse spreading code (ISC) corresponding to the spreading code (SC). The spreading code (SC) comprises a time spreading element (SFtime) indicating the amount of spreading in the time domain and a frequency spreading element (SFfreq) indicating the amount of spreading in the frequency domain.