Abstract: Disclosed is a method for use in a multiple-input multiple-output (MIMO) communication network in which the network includes a plurality of cells provided by one or more base stations operable to transmit signals on at least one downlink to, and receive signals on at least one uplink from, one or more user equipments. A user equipment feeds back to the network reports on channel state information, CSI, relating to one or more channels between base stations and that user equipment, and base stations adapt downlink signals to user equipments based on the CSI reports, the method including: identifying uplink resources for a user equipment-initiated channel state message; the user equipment judging a need for a user equipment-initiated channel state message based on information not available to the network; and the user equipment sending the user equipment-initiated channel state message to the network using the uplink resources identified.

Abstract: A wireless communication system is described which includes a transmitter operable to transmit a transmitted signal, the transmitter having one or more transmitting antennae, a receiver operable to receive a received signal, the receiver having one or more receiving antennae, wherein lattice reduction is used in obtaining, at the receiver, an estimate of the transmitted signal based on the received signal, characterized in that the lattice reduction utilizes a lattice reduction matrix, a decomposed representation of which is transmitted between the transmitter and the receiver.

Abstract: A multiple-input multiple-output (MIMO) wireless communication systems that includes a plurality of adjacent cells, each containing one or more base stations operable to transmit signals to, and receive signals transmitted from, one or more users. The users are operable to feed back to the relevant base station(s) channel state information relating to channel(s) between the relevant base station(s) and the users, and the base stations are operable to adapt signals for transmission to users, based on the fed back channel state information, to account for channel variations. The proposed method involves obtaining information related to time-variation in channel spatial structure, and adjusting the timing with which a user feeds back channel state information, based on the time variation in channel spatial structure. The invention helps to achieve a suitable balance between the feedback overhead and system performance, and may be operable in systems operating according to various CoMP transmission modes.

Abstract: A method of selecting a cell or cells for use in multiple-input/multiple-output (MIMO) transmission to user equipment or a relay station in a serving cell of a cellular wireless network, there being a set of N cells of the cellular network from which a selection of cells is to be made, N being an integral number greater than one and the set including the serving cell, the received signal power of the serving cell and the received interference power of the other cells in the set relative to the serving cell are sorted in descending order of power P, such that P0?P1? . . . ?PN-1, and a group of M cells are selected from the said set of N cells, where the cells selected are those giving the smallest value of M for which the inequality ? k = 0 M - 1 ? P k ? ? ? ? i = 0 N - 1 ? P i is satisfied, ? being a first decision threshold parameter.

Abstract: A method of controlling handover in wireless cellular networks of user equipment in a first cell unit which is to be disabled to a second cell unit which is to provide extended coverage for the, or part of the, first cell unit, where the cell unit of the first and second cell units is a cell or a cell sector, including selecting a part of the signal bandwidth or time-frequency resource units, previously designated for use in normal operation by the second cell unit, which does not overlap with that to be used by the first cell unit during the handover; and designating the selected part for use by the user equipment to be handed over from the first cell unit.

Abstract: A method of scheduling coordination among cells in a cellular wireless network involving multiple-input/multiple-output (MIMO) communication. A first scheduling process selects user equipment within the said cell to be served by a coordinating group of cells in the network, and a second scheduling process group of cells to serve as a coordinating group for the user equipment, for which measurements are sent by the selected user equipment. The second scheduling process determines which group of cells, from a set of all possible groups of cells, provides the best value of a particular selection parameter used. The selection parameter may, for example be dependent upon the long-term link power coupling weights PW(ci) and spatial correlation weights d(ci) between user equipment in the cells.

Abstract: A multiple-input multiple-output (MIMO) wireless communication systems that includes a plurality of adjacent cells, each containing one or more base stations operable to transmit signals to, and receive signals transmitted from, one or more users. The users are operable to feed back to the relevant base station(s) channel state information relating to channel(s) between the relevant base station(s) and the users, and the base stations are operable to adapt signals for transmission to users, based on the fed back channel state information, to account for channel variations. The proposed method involves obtaining information related to time-variation in channel spatial structure, and adjusting the timing with which a user feeds back channel state information, based on the time variation in channel spatial structure. The invention helps to achieve a suitable balance between the feedback overhead and system performance, and may be operable in systems operating according to various CoMP transmission modes.

Abstract: A wireless communication system is described which includes a transmitter operable to transmit a transmitted signal, the transmitter having one or more transmitting antennae, a receiver operable to receive a received signal, the receiver having one or more receiving antennae, wherein lattice reduction is used in obtaining, at the receiver, an estimate of the transmitted signal based on the received signal, characterized in that the lattice reduction utilises a lattice reduction matrix, a decomposed representation of which is transmitted between the transmitter and the receiver.

Abstract: A method of selecting a cell or cells for use in multiple-input/multiple-output (MIMO) transmission to user equipment or a relay station in a serving cell of a cellular wireless network, there being a set of N cells of the cellular network from which a selection of cells is to be made, N being an integral number greater than one and the set including the serving cell, the received signal power of the serving cell and the received interference power of the other cells in the set relative to the serving cell are sorted in descending order of power P, such that P0?P1? . . . ?PN-1, and a group of M cells are selected from the said set of N cells, where the cells selected are those giving the smallest value of M for which the inequality ? k = 0 M - 1 ? P k ? ? ? ? i = 0 N - 1 ? P i is satisfied, ? being a first decision threshold parameter.

Abstract: A cell edge coverage hole detection method for a cellular wireless communication system such as an LTE system. A coverage hole in a cell edge region will cause radio link failures, RLF, which are difficult to distinguish from those caused by handover issues. The method collects (S10) RLF reports along with related connectivity patterns and location reports, and identifies (S20) a drive route across a cell edge at which radio link failures are occurring. By correlating (S30) the measurement reports from users travelling in both directions along the route, it can be judged (S40) whether a pattern specific to a coverage hole can be identified, distinguishing coverage holes (S60) from radio link failure occurring as a result of handover failure (S50).

Abstract: A cell edge coverage hole detection method based on collecting (S10) radio link failure, RLF, statistics provided by multiple UE reports at the handover stage. At a cell edge, the handover point varies for each UE due to the differences in parameter settings and measurement values, giving a statistical distribution of the exact handover point. In the method, RLF reports are grouped by connectivity pattern and a specific cell edge is identified for closer investigation (S20). Hysteresis and/or offsets are varied for UEs at the cell edge and subsequent RLF reports are monitored for changes in tendencies of event sequences (S30). If RLF persists for most of the UEs, the method infers from this (S40, S60) the existence of a coverage hole.