The patent's assignee for patent number 8654725 is
News editors obtained the following quote from the background information supplied by the inventors: "A geographical area covered by a cellular wireless telecommunications network may be separated into a patchwork of smaller geographical areas or cells, which are each served by a base station. Each base station communicates with end user equipments, which subscribe to the network operator of the network and which are located within the cell served by the base station. A network controller coordinates the transmission of messages, comprising for example voice or data, via the base stations. For optimum coverage over a cell, the base station may transmit and receive messages over one or more Frequency Division Duplexes (FDDs). In a FDD a first channel at a first frequency is used constantly as a downlink, for carrying messages from the base station to user equipments within the cell. A second channel, at a different frequency from the first is used constantly as an uplink for carrying messages from the user equipments within the cell to the base station.
"However, there can be a problem that some user equipments within the cell may not be able to communicate with the base station over the FDD because for example, there is an obstacle between the base station and the end user equipment. For example, it may be that user equipments located on an upper floor of a building can communicate with the base station, whereas user equipments located on a lower floor or in the basement of the building cannot communicate with the base station. One way of solving this problem is to install repeater units adjacent to regions of a cell where coverage is poor. The repeater units, receive messages from the base station and re-transmit them to the user equipments and receive messages from the user equipments and retransmit them to the base station. As the repeaters transmit and receive the messages at a location closer to the user equipments than the base station, user equipments in the poor coverage region of the cell have a good chance of establishing communication with the base station via the repeater. However, repeater units are relatively expensive and the deployment of repeaters in regions with high user density, such as urban environments, can be prohibitively expensive because of the shortage of sites for the location of repeater units and the high rental costs for such locations. Also, the deployment of repeater units in regions of low user density, such as rural environments, is not cost effective as the numbers of user equipments in cell regions with poor coverage is generally too low.
"Investigations have also been carried out to try to improve capacity within cells. One way to do this is to use one or more base station equipments operating in Time Division Duplex (TDD) mode in addition to the FDD mode. In the TDD mode the same frequency channel is used for communications from the base station to the user equipments and from the user equipments to the base station, with the direction of transmission of messages on the channel varied in a controlled way so that the transmission of messages at any given time is one way.
"However, TDD is not ideally suited for wide area coverage. In order to improve coverage within the poor coverage regions of a cell having a TDD infrastructure, relatively simple TDD relays can be deployed. The TDD relays may include relay units specifically deployed by the network operator of user equipments and/or end user equipments equipped with a TDD relay capability. Simple relays and user equipments can be used because TDD is ideally suited to relay because the same channel can be used for receipt and re-transmission of the relayed message, with the receipt and retransmission separated in time so that the TDD for the relay has changed from a receive mode to a transmit mode.
"The situation is more complicated where the base station has a FDD infrastructure. This is because for an FDD repeater the uplink and downlink channels must be reversed in frequency so as to ensure that a standard end user equipment can be used, This frequency swapping creates the potential for self interference where the repeater transmitter may cause interference to the repeater receiver. Alternatively, the FDP repeater can map the FDD system into another spectrum allocation to avoid self interference, however, this requires the end user equipment to be multi-band and still the repeater may be interfered with or cause interference to other systems. Therefore, it has been suggested in order to extend high bit data rate FDD coverage to the periphery of a cell, which periphery can support only low bit data rate FDD coverage, that a static relay node may be deployed by the network operator at the border between the high bit data rate coverage area and the periphery of the cell. The static relay node would receive a message at the high bit data rate over a base station FDD and relay it, at the high bit data rate, on a TDD towards its destination. Although FDD/TDD repeaters will be less prone to the self interference effects (the TDD onwards transmiHssion will be, at worst, in an adjacent band, rather than in-band as is the case for co-channel FDD) they suffer similar disadvantages to FDD only repeaters. Fixed repeater installations of all types are likely to attract similar site location and rental issues."
As a supplement to the background information on this patent, VerticalNews correspondents also obtained the inventor's summary information for this patent: "The present invention relates generally to a telecommunications network, in particular a wireless cellular telecommunications network including a base station, an intermediate end user equipment and an other end user equipment. The intermediate end user equipment includes a FDD/TDD relay for relaying data between a FDD between the base station and the intermediate end user equipment and a TDD between the intermediate end user equipment and the other end user equipment.
"In accordance with a first aspect of the invention, there is provided a telecommunications network comprising: a base station; an intermediate user equipment; and an other user equipment; the intermediate user equipment having a frequency division duplex (FDD) transceiver for communicating directly with said base station over a FDD, a time division duplex (TDD) transceiver for communicating with the other user equipment over a TDD and an interface for interfacing said FDD and TDD to establish a communication link between the base station and the other user equipment.
"In accordance with a second aspect of the present invention there is provided an intermediate end user equipment for use in a telecommunications network, which network also includes a base station and an other end user equipment, wherein the intermediate end user equipment includes: a FDD transceiver for communicating directly with the base station over a FDD; a TDD transceiver for communicating over a TDD with the other end user equipment; and an interface for interfacing said FDD and TDD to establish a communication link between the base station and the other user equipment.
"The first and second aspects of the present invention provide the advantage of enabling improved capacity and coverage within a network having a primarily FDD infrastructure, without the network provider having to deploy additional relay or repeater units in poor network coverage areas. For example, an end user having a mobile telephone and a mobile computing device may find themselves working in a building where network coverage is good upstairs but poor downstairs. In this case the end user could leave their mobile phone in a transceiving mode in an upstairs room, so that it could act as an intermediate end user equipment for a mobile computing device being used in a downstairs room, or vice versa. In an office building where some workers in the basement cannot communicate directly with a base station, end user equipments on the upper floors could be used as intermediate end user equipments so that destination or terminal (ie. other) end user equipments in the basement could communicate indirectly with the base station via TDD communications with the intermediate end user equipments. In the above examples, it may be that the destination or terminal end user equipments can only communicate with the base station over a low bit data rate communication whereas communication via an intermediate end user equipment may enable a high bit data rate communication to be achieved.
"Also, the present invention enables unpaired TDD spectrum, licensed by the network provider and which is largely unused, to be used in a network with a primarily FDD infrastructure. The present invention enables the utilization of TDD spectrum without the deployment of TDD infrastructure by the network provider In addition it may be possible to share spectrum with other operators or use unlicensed (license exempt) spectrum since the probability of interference is likely to be low and interference limiting protocols, such as `listen before talk` or central scheduling could be employed.
"In order to prevent interference between messages sent over the TDDs within the network, the FDD/TDD interface may include a synchronization unit for synchronizing the transmission of frames over the TDD with the transmission of frames over the FDD. Then a network controller, for example a base station controller or Radio Node Controller (RNC) may allocate TDD resource to intermediate user equipments. Where the FDD and TDD frames are synchronized, if a first intermediate end user equipment is allocated a first set of time slots over which to transmit over a TDD channel and a second intermediate user equipment is allocated a different set of time slots over which to transmit over the TDD channel, then the TDD transmissions made by the first and second intermediate end user equipments will not generate interference. In order to intelligently re-use TDD resource within a cell the network controller may allocate TDD resource within the cell to intermediate user equipments dependent on the location of the intermediate user equipments.
"The user equipments may be mobile equipments, such as mobile telephones, mobile computing devices or Personal Digital Assistants (PDAs). Alternatively, the end user equipments may be nomadic equipments, such as computing devices, for example, lap top computers that are generally static when in use but which do not always have the same location.
"In order to reduce the complexity of the FDD/FDD interface in the intermediate end user equipment the frames transmitted over the TDD may be configured to have the same structure as frames transmitted over the FDD. Also, the same coding and decoding scheme and the same modulation technique may be used for data transmitted over the TDD as is used for the FDD. This enables mapping of messages from timeslots in a FDD frame to timeslots in a TDD frame and vice versa, thus avoiding the need to dissemble/re-assemble the data.
"The intermediate end user system may not be able to directly communicate over a TDD with a terminal one of the user equipments, in which case the other end user equipment may include; a TDD transceiver for communicating with the intermediate user equipment and a second other user equipment over a TDD; and a TDD relay for relaying messages between the intermediate end user equipment and the second other user equipment.
"The last hop to a terminal one of the other end user equipments may be via a short range technology link, such as intra-red, blue tooth or wireless LAN.
"It may be possible to use end user equipments which subscribe to a network operator other than the network operator for the telecommunications network as the intermediate end user equipment. This provides a greater number of potentially available intermediate end user equipments.
"According to a third aspect of the present invention there is provided a method of communicating messages in a telecommunications network comprising a base station, an intermediate user equipment and a terminal user equipment, wherein an outgoing message is communicated from the base station to the terminal end user equipment by the steps of; the base station sending an outgoing message to an intermediate end user equipment directly via a FDD downlink; the intermediate end user equipment receiving the outgoing message, storing the message and reconfiguring the message for transmission over a TDD; the intermediate end user equipment transmitting the reconfigured outgoing message over a TDD directly or indirectly to the terminal end user equipment; and/or wherein an incoming message is communicated from the terminal end user equipment to the base station by the steps of: the intermediate end user equipment receiving an incoming message directly or indirectly from the terminal end user equipment over a TDD; the intermediate end user system storing the incoming message and reconfiguring the message for transmission over a FDD link; and the intermediate end user system transmitting the reconfigured incoming message directly over a FDD to the base station.
"The method according to the third aspect of the present invention has the same advantages as are described above in relation to the first and second aspects of the present invention.
"The telecommunication services supported in a communication between the base station and a terminal or destination user equipment via an intermediate user equipment would be dependent on the service contract between the user of the terminal user equipment and the service provider.
"A financial credit or a free call time credit may be allocated to an intermediate end user equipment for supporting a communication between the base station and a terminal or other user equipment. This would provide an incentive to an end user to keep their user equipment switch on in an FDD/TDD transceiving mode when it is not being used, so that the user equipment can be utilized by the telecommunications network for relaying messages.
"Other aspects and features of the present invention will become apparent to those ordinarily skilled in the art upon review of the following description of specific embodiments of the invention in conjunction with the accompanying Figures."
For additional information on this patent, see: Edwards,
Keywords for this news article include: Telecommunications,
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