GB2480485A

GB2480485A - Activating femtocell antennas based on device location

Info

Publication number: GB2480485A
Application number: GB1008450A
Authority: GB
Inventors: Yong Sun; Zhong Fan
Original assignee: Toshiba Research Europe Ltd
Current assignee: Toshiba Europe Ltd
Priority date: 2010-05-20
Filing date: 2010-05-20
Publication date: 2011-11-23
Also published as: GB201008450D0

Abstract

In a small office/home (SOHO) femtocell network comprising sets of antennas (52), each set of antennas (eg. 52a-c) is switched between active and inactive states based on the location of wireless device (eg. laptop 54) received via a Radio Frequency Identification (RFID) tag from the device. This overcomes indoor interference in the femtocell without requiring the Home Node B (HNB) antennas to operate wastefully at fixed transmission power. A reference antenna is continually active to maintain signalling with the user equipments (UEs) via millimetre-wave (mmWave) or power line connections.

Description

WIRELESS COMMUNICATION METHOD AND APPRATUS

Field of the Invention

The present invention relates to wireless communication. It is particularly, but not exclusively, concerned with wireless communication in a femtocell network.

Backciround of the Invention Over the last decade mobile communication has become increasingly in demand, particularly due to the growth of multimedia communication services, such as video streaming, video conferencing, packet data transfer and so on. As a result, mobile phones have also become indispensable in everyday life.

It is hence desirable for mobile operators to improve coverage and provide high data rate services in a cost effective manner. In order to ensure that a mobile communication network can service a large geographical area, it is often necessary in practice to locate base stations in every necessary location in order to provide a perfect coverage.

Many wireless communication networks are constructed based on a "cellular" topology, whereby each user terminal or device is assigned to communicate with a subset (typically one) of one or more base stations. The geographical area that is covered by a given base station's transmission is known as a "cell".

Some examples of such cellular systems include second-generation GSM (Global System for Mobile Communications) networks and third generation (3G) UMTS (Universal Mobile Telecommunications System) networks, all of which support wireless transmission of voice and data information.

A macrocell is a cell in a mobile communication network that provides radio coverage served by a power cellular base station tower. In mobile communications system, the term macrocell is used to describe the widest range of ce sizes. Generally, macrocells provide large area coverage, and are found in rural areas or along motorways, The antennas for macrocells are mounted on ground-based masts, rooftops, and existing structures, at a height that provides a clear view over the surrounding buildings and terrain. Macrocell base stations have power outputs of typically tens of watts.

For a smaller cell area, a microcell is used to describe a cell intended for covering a densely populated urban area. Picocells are employed in areas even smaller than microcells, such as a large office, a shopping mall, or a transport hub. Currently the smallest area of coverage can be implemented with a femtocell in homes or small offices.

A femtoceU is a small low power base station designed for use in small coverage areas such as residential or small business environments. In contrast with a macrocell base station, a femtocell base station usually has an output power less than 0.1 watt. A femtocell base station is typically installed by a subscriber in a house or small office/home office (SOHO) to provide access to a closed or opened group of users as configured by the subscriber and/or the access provider. The femtocell base station connects to the service provider's network via broadband (such as DSL or cable); and typically supports 2 to 4 active mobile terminals in a residential setting.

The mobile terminal described in the present invention may include mobile phones, laptops, Personal Digital Assistants (PDA5), and the like, and fixed terminals with wireless connection such as desktop and digital televisions. Throughout the description, the term "mobile terminal" may be used interchangeably with the term "User Equipment (UE)".

An overview of a femtocell architecture 12 is shown in figure 1. Femtocell base stations, also known as femtocell access points (or Home Node B -HNB), typically operate in licence spectrum and may be deployed either in the same or different frequency as the macrocell base stations. The femtocell base stations coverage may also overlap the macrocell base stations.

As shown in figure 1 the femtocell 16 is typically deployed on top of the existing macrocell network 14 to improve coverage in limited locations, such as indoor environments. Therefore a femtocell base station (or access point base station) 20 is usually installed at locations where users are. experiencing unsatisfactory radio coverage. The femtocell base station 20 is connected to a service provider network via broadband DSL (digital subscriber line) or other IP connection 22 which is in turn connected to a femtocell controller/gateway 24 in order to interface with a GSM or UMTS core packet switched and circuit switched network 10.

The macrocell base station 18 is connected to a radio network controller (RNC) 36 which is responsible for control of the base stations that are connected to it. As known in the art, the responsibilities of the RNC 36 further include radio resource management (RRM) and handoff between BSs. The RNC 36 is in turn connected to a serving GPRS support mode (SGSN) 28 which is connected to a network operator IP network 26. The femtocell gateway 24 is also connected to the operator IP network 26, as shown in figure 1. The RNC 36 is further connected to a mobile switching centre (MSC) 34 to then be connected to the public switch telephone network (PSTN) 32.

The fundamental idea of femtocells is to allow cellular service providers to extend their service coverage indoors, especially in the original concept where access would otherwise be limited or unavailable. Essentially, the femtocell incorporates the functionality of a typical base station but extends it to allow a simpler, self contained deployment. However, as the femtocell is deployed without a unique spectrum for the femtocell underlay network or careful spectrum planning in the wider network, it is noted that femtocells often suffer from severe interference problems.

A number of solutions have been proposed to overcome the interference problems.

For example, the femtocell may be implemented using a different frequency, managing the interference on top of the system operation, or allocating extra radio resources to the femtocell.

In addition, the transmit power of the HNB needs to be adapted to provide acceptable performance. In particular, the HNB needs to transmit sufficient amount of power to communicate with UEs that are located at the boundary of the femtocell. Similarly, the UEs located at the boundary of the femtocell operate at full power in order to maintain connection with the HNB. A severe interference problem can occur when transmission of high power result in interference to neighbouring femtocells and/or macrocells.

Furthermore, the transmission power of the HNB is fixed regardless of whether the UE is located close to the HNB or the boundary of the femtocell. This has a significant drawback in that it results in a waste of resources when the UE is located close to the HNB.

Summary of the Invention

In a first aspect of the invention there is provided a method of establishing communication between a wireless device and a further wireless device in a network, the wireless device comprises a set of antennas distributed in the network, wherein each of said set of antennas is configured to switch between an active state and an inactive state, the method comprising: obtaining, at the wireless device, location identity of a subset or whole of the entire set of antennas; obtaining location information of said further wireless device; selecting at least one of antennas for communication with said further wireless device based on said obtained location identity and said location information; switching said selected antenna to said active state; and wherein subsequent to said switching being performed, said wireless device is in communication with said further wireless device.

The step of obtaining location identity may comprise receiving an REID signal from said each of said set of antennas.

The step of obtaining location information of said further wireless device may comprise receiving a further RFID signal from said further wireless device.

The step of selecting may comprise determining said at least one of said subset or set of antennas that are located in the vicinity of said further wireless device, based on said obtained location identity and said location information.

In a second aspect of the invention there is provided a method of establishing communication between a wireless device and a further wireless device in a network, the wireless device comprises a set of antennas distributed in the network, wherein each of said set of antennas is configured to switch between an active state and an inactive state, the method comprising: obtaining, at the wireless device, location identity of a subset or whole of the entire set of said antennas; obtaining, at the further wireless device, location identity of at least one of said set of antennas that are in the vicinity of the further wireless device, and sending said obtained location identity to the wireless device; selecting at least one of said at least one of said set of antennas based on said obtained location identity of said at least one of said antennas; switching said selected antenna to said active state; and wherein subsequent to said switching being performed, said wireless device is in communication with said further wireless device.

The step of obtaining location identity may comprise receiving an RFID signal from said each of said set of antennas.

The step of sending said obtained location identity may comprise transmitting an RFID signal from said further wireless device to said wireless device.

The step of switching may be performed via a millimetre-wave connection or a powerline connection.

In one embodiment of the above aspects the method further comprises monitoring movement of the wireless device within said network by determining whether the further wireless device is in the vicinity of the selected antenna.

In a further embodiment of the above aspects, the method further comprises obtaining a further location information of said further wireless device and selecting a further at least one of said subset or set of antennas based on said location identity and said obtained further location information if said wireless device is not in the vicinity of the selected antennas.

In another embodiment of the above aspects, the method further comprises obtaining, at the further wireless device, location identity of a further at least one of subset or set of said antennas that are in the vicinity of the wireless device, and sending said obtained location identity to the wireless device, and selecting, at the wireless device, at least one of said further at least one of subset or set of antennas based on said obtained identity if said further wireless device is not in the vicinity of the selected antenna.

In an embodiment of the above aspects, the method further comprises controlling transmit powers at the selected antenna and the selected further antenna.

In an embodiment of the above aspects, the method further comprises switching the selected antenna to said inactive mode and switching the selected further antenna to said active mode.

In a third aspect of the invention, there is provided a system for establishing communication between a wireless device and further wireless device in a network, said wireless device comprises a set of antennas distributed in the network, wherein each of said set of antennas is configured to switch between an active state and an inactive state, the system comprising: means for obtaining a location identity of a subset or whole of the entire set of antennas; means for obtaining location information of said further wireless device; means for selecting at least one of said antennas for establishing communication between said wireless device and said further wireless device; switching means for switching said selected antennas to said active mode; and wherein subsequent to said switching being performed, said wireless device is in communication with said further wireless device.

In a fourth aspect of the invention there is provided a system for establishing communication between a wireless device and a further wireless device in a network, the wireless device comprises a set of antennas distributed in the network, wherein each of said set of antennas is configured to switch between an active state and an inactive state, the system comprising: means for obtaining a location identity of a subset or whole of the entire set of said antennas; means for obtaining location identity of at least one of said set of antennas that are in the vicinity of the further wireless device, and sending said obtained location identity to the wireless device; means for selecting at least one of said at least one of said set of antennas based on said obtained location identity of said at least one of said antennas; switching means for switching said selected antenna to said active state; and wherein subsequent to said switching being performed, said wireless device is in communication with said further wireless device.

In a fifth aspect of the invention, there is provided an apparatus for establishing communication with a wireless device in a network, the apparatus comprises a set of antennas distributed in the network, wherein each of said set of antennas is configured to switch between an active state and an inactive state, the apparatus further comprising: means for obtaining location identity of a subset or whole of the entire set of antennas; means for obtaining location information of said wireless device; means for selecting at least one of said antennas for communication with said wireless device based on said obtained location identity and said location information; switching means operable to switch said selected antenna to said active state, wherein subsequent to said switching being performed, said apparatus is in communication with said wireless device.

The means for obtaining location identity may comprise an RFID receiver configured to receive RFID signals from said each of said set of antennas.

The means for obtaining location information may comprise a further RFID receiver configured to receive RFID sighals from said wireless device.

The means for selecting may be operable to determine said at least one of said subset or set of antennas that are located in the vicinity of said wireless device, based on said obtained location identity and said obtained location information.

In a sixth aspect of the invention, there is provided an apparatus for establishing communication with a wireless device in a network, the apparatus comprises a set of antennas distributed in the network, wherein each of said set of antennas is configured to switch between an active state and inactive state, the apparatus further comprising: means for obtaining location identity of a subset or whole of the entire set of said antennas; means for receiving location identity information from said wireless device; means for selecting at least one of said at least one of said set of antennas based on said obtained identity of said at least one of said antennas; switching means for switching said at least one of said selected antennas to said active state, and wherein subsequent to said switching being performed, said apparatus is in communication with said wireless device.

The means for obtaining location identity may comprise an RFID receiver configured to receive an REID signal from each of said set of antennas.

The means for receiving may comprise a further REID receiver configured to receive location identity information from said wireless device.

The switching means may be operable to communicate with said set of antennas via a millimetre-wave connection or a powerline connection.

In an embodiment of the above aspects, the apparatus further comprises means for monitoring movement of said wireless device within said network, said means for monitoring is configured to determine whether said wireless device is in the vicinity of the selected antennas.

The monitoring means may be operable to obtain location information of said wireless device and to select a further at least one of said subset or set of antennas based on said location identity and said obtained information if said wireless device is not in the vicinity of the selected antennas.

Alternatively, the monitoring means may be operable to receive location identity of a further at least one of subset or set of antennas that are in the vicinity of the wireless device, and selecting at least one of said further at least one of subset or set of antennas based on said obtained identity if said wireless device is not in the vicinity of the selected antennas.

In an embodiment of the above aspects, the apparatus further comprises power control means for controlling transmit powers at the selected antennas and the selected further antennas.

The switching means may be further configured to switch the selected antennas to said inactive mode and to switch said selected further antennas to said active mode.

In a seventh aspect of the invention, there is provided an apparatus for establishing communication with a wireless device in a network, the wireless device being provided with a set of antennas distributed throughout the network, wherein each of said set of antennas is configured to switch between an active and an inactive state, the apparatus comprising: means for transmitting location information of said apparatus to said wireless device.

The means for transmitting may comprise an RFID tag.

An aspect of the invention provides a computer program product comprising computer executable instructions which, when executed by a computer, cause the computer to perform a method as set out above. The computer program product may be embodied in a carrier medium, which may be a storage medium or a signal medium. A storage medium may include optical storage means, or magnetic storage means, or electronic storage means.

Description of the drawings

Embodiments of the invention will now be described with reference to the accompanying drawings, wherein: Figure 1 illustrates a conventional UMTS architecture and the basic elements of a femtocell architecture according to described prior art; Figure 2 illustrates a plan view of a house; Figure 3 illustrates a plan view of the house of figure 2 in which a femtocell is deployed with distributed antennas according to an embodiment of the invention; Figure 4a illustrates a plan view of the house of figure 2 in which a femtocell is deployed with distributed antennas according to a further embodiment of the invention; Figure 4b illustrates a plan view of the house of figure 2 in which a femtocell is deployed with distribute antennas according to another embodiment of the invention; Figure 5 illustrates apparatus for establishing communication links between the distributed antennas and a HNB; Figure 6 illustrates an exemplary wireless communications device incorporating described embodiments of the invention; Figure 7 illustrates a flow diagram of a method operating distributed antennas in a femtocell according to an embodiment of the invention; Figure 8 illustrates a graph that indicates path loss over distance.

Detailed description

Specific embodiments of the present invention will be described in further detail on the basis of the attached diagrams. It will be appreciated that this is by way of example only, and should not be viewed as presenting any limitation on the scope of protection sought.

Distributed antenna systems (DAS) have been deployed in mobile communications for many years. A DAS is a network of spatially separated antenna nodes connected to a common source via a transport medium that provides wireless service within a geographic area. The DAS is described herein for providing coverage in a femtocell such as a home or office environment.

The embodiments of the invention are provided with N number of distributed antennas, although it is appreciated that the HNB can simultaneously support and/or operate a limited M number of distributed antennas (M<<N); A femtocell coverage is normally a small area or zone which has a specific and clear boundary, such as a house 40 with living areas 42, 44, 46, 48, 50, as illustrated in figure 2.

In an exemplary embodiment of the invention, the antennas of the DAS are distributed throughout the whole femtocell to relay wireless signals between the HNB and the UEs within the coverage area. Figure 3 illustrates a plan view of the house 40 of figure 2 comprising a DAS 52 implemented throughout the house 40 in a grid arrangement 52.

Such a configuration divides the femtocell coverage area into a number of small areas (or sub-areas). It will be appreciated that other configurations can also be employed, depending on the cost, application and requirements. Figures 4a and 4b illustrate alternative arrangements of the DAS 52 implemented in the house 40 of figure 2.

Figure 4a illustrates an arrangement where the antennas 52 are distributed along the boundary of the house 40. Figure 4b illustrates an arrangement where the antennas 52 are distributed in such a way that each room in the house 40 is provided with an antenna 52.

The concept of deploying a DAS in a femtocell is to utilise several antennas over the required coverage area. It will therefore be appreciated that embodiments of the present invention can operate with a lower overall transmit power, as more localised antennas are placed more effectively to provide coverage for a smaller area (sub-area).

Each of the antennas is only switched on (active) when a UE moves into the sub-area covered by that antenna. Therefore, most of the DAS antennas, which are not providing coverage, are switched off (inactive). This would overcome, or at least ameliorate, the interference problems described in the preceding paragraphs. This provides a significant advantage over a conventional femtocell arrangement where a single high transmit power antenna is used for the wider coverage needed. In addition, as line-of-sight (LOS) link is also available more frequently, the embodiments of the present invention would also reduce shadowing and penetration loss.

The present invention will now be described with reference to an implementation of a wireless communication device. Figure 5 illustrates schematically hardware operably configured (by means of software or application specific hardware components) as a wireless communication device 100. The reader will appreciate that the actual implementation of the wireless communication device is non-specific, in that it could be a base station, a femtocell HNB, or a mobile terminal (a UE).

The device 100 comprises a processor 120 operable to execute machine code instructions stored in a working memory 124 and/or retrievable from a mass storage device 122. By means of a general purpose bus 130, user operable input devices 136 are capable of communication with the processor 120. The user operable input devices 136 comprise, in this example, a keyboard and a mouse though it will be appreciated that any other input devices could also or alternatively be provided, such as another type of pointing device, a writing tablet, speech recognition means, or any other means by which a user input action can be interpreted and converted into data signals.

Audio/video output hardware devices 138 are further connected to the general purpose bus 130, for the output of information to a user. Audio/video output hardware devices 138 can include a visual display unit, a speaker or any other device capable of presenting information to a user.

Communications hardware devices 132, connected to the general purpose bus 130, are connected to antennas 134. In the illustrated embodiment in figure 5, the working memory 124 stores user applications 126 which, when executed by the processor 120, cause the establishment of a user interface to enable communication of data to and from a user. The applications in this embodiment establish general purpose or specific computer implemented utilities that might habitually be used by a user.

Communications facilities 128 in accordance with the specific embodiment are also stored in the working memory 124, for establishing a communications protocol to enable data generated in the execution of one of the applications 126 to be processed and then passed to the communications hardware devices 132 for transmission and communication with another communications device. It will be understood that the software defining the applications 126 and the communications facilities 128 may be partly stored in the working memory 124 and the mass storage device 122, for convenience. A memory manager could optionally be provided to enable this to be managed effectively, to take account of the possible different speeds of access to data stored in the working memory 124 and the mass storage device 122.

On execution by the processor 120 of processor executable instructions corresponding with the communications facilities 128, the processor 120 is operable to establish communication with another device in accordance with a recognised communications protocol.

In the described embodiments, certain assumptions are established: * The HNB comprises a reference antenna, separated from the antennas of the DAS, for reference signalling and control with the UEs in the femtocell. The reference antenna is continually switched on to maintain signalling and control with the UEs. Alternatively, one of the distributed antennas may also be configured to function as a reference antenna.

* Wireless connection between the HNB and the distributed antennas are established via millimetre-wave (mmWave) and/or power-line; * In order to detect the location and movement of the UEs, REID tags are employed on the antennas and the UEs; * A switch on/off procedure is employed for mobility management in the femtocell.

A femtocell typically supports 2 to 4 active mobile terminals (UE5). Therefore, it is noted that only a small number of antennas 52 are needed to be active in order to provide the required services to the tiEs in their respectiv.e sub-areas. As an example, Figure 3 illustrates that antennas 52a, 52b, 52c, and 52d, and antennas 52e and 52f are switched on to provide coverage to a notebook computer 54 and a handset 56 respectively. The distributed antennas in the femtocell are configured to switch from one to another as the tiEs 54, 56 move from one sub-area to another sub-area.

In one example of present invention, it is assumed that a large set of antennas are distributed in a femtocell. The number of antennas, in this example, is much greater than the capacity that a HNB can handle simultaneously. In practice, the maximum number of antennas that that HNB can support is usually limited, for example, to 8 antennas per HNB. For ease of describing the invention, it is assumed that the number of distributed antennas is N, the maximum number of antennas supported by the HNB is M, and the number of antennas required for transmission is k. According, k«=M<<N (1) M is effectively the maximum number of antennas supported by a HNB and can also be shared among different UEs within the femtocell. Therefore, the UEs can be separated in the spatial domain with their "own" distributed antenna(s). Accordingly, equation (1) can be expressed as: k<M<<N i=1,...,p (2) k«=M when p=l where p is the number of active UEs supported by the HNB simultaneously. In this example, the HNB is configured to include all the antenna units in its operation such as antenna localisation and connection.

A centralised antenna (not shown) is provided to enable communication between the HNB and the UEs 54, 56 so as to determine which of the distributed antennas are to be switched on for transmission. The centralised antenna can either be located on the HNB or configured as a part of the distributed antennas set. One advantage of employing a centralised antenna using the distributed antennas set is that the distributed antennas can be arranged such that the centralised antenna is always in a centralised location from all the UEs. The centralised antenna can also either be a single antenna or multiple antennas configuration, depending on the transmission configuration of the system.

The centralised antenna is configured mainly for signalling and control operation, which is separated from data transmission. The transmission of the centralised antenna is configured for signalling high quality but low power signal to avoid interference with the data transmission.

It is also appreciated that the signalling and control operation can also be integrated with data transmission. However, the transmission power of the signalling and control operation must be maintained at a substantially low level to avoid any emission outside the boundary of the femtocell.

To minimise the delay in transmission, the HNB employs continuous transmission on signalling through the centralised antenna and data transmission using the distributed antennas set. This configuration of the centralised antenna avoids any interruption to the communication between the HNB and UEs.

The connections between the HNB and the DAS are set up using the following means: 1. millimetre-Wave (mmWave) Gbits wireless link (HD wireless link); or 2. power-line.

In a mmWave Gbits wireless link configuration, the uplink RF signals received by the active distributed antennas are converted into mmWave at the active distributed antenna before being transmitted to the HNB via the mmWave wireless link, and vice versa. As illustrated in Figure 6, a mmWave modem 60 is provided at both the distributed antenna and the HNB.

As shown in figure 6, the system operates in two frequencies, namely: f1 and f2 for the HNB RF and the mmWave signals respectively. The frequencies are configured as: fi <<f2 (3) As f2 is much greater than f the mmWave transmission are used mainly for short distance LOS communications.

In a power-line configuration, each of the distributed antennas is connected to a closest point of power socket. Essentially, the power-line transmission is operated by impressing a radio signal on the wiring system. It is appreciated that different types of power-line communications use different frequency bands, depending on the signal transmission characteristics of the power wiring used. It is further noted that higher data rates can generally be transmitted in shorter ranges to cover one floor of an office building or a home environment. The power-line transmission requires a modem to be implemented at both ends (the HNB and the distributed antennas), and data rates up to several hundred Mbps can be achieved.

The power-line transmission can be implemented for low and mediun data rate, as its capacity and throughput are limited. For a high data throughput, the mmWave wireless link would be the preferred solution, as gigabits data rate can be acheived.

In an indoor environment, mobile terminals tend to move at a relatively slow speed compared to mobile terminals in an outdoor cellular environment. The distributed antennas of the present invention are switched from one zone to another as the mobile terminal moves within the femtocell. It is noted that the concept of switching from one zone to another is different from the conventional concept of "handover" applied in cellular applications, as each zone of the DAS is not always active.

In one embodiment of the invention, joint localisation technique and sensors may be applied to manage the connectivity of the moving UEs. For example, the coverage of two adjacent zones can be heavily overlapped to allow the UEs to be covered by several distributed antennas.

In the embodiments of the present invention, each of the distributed antennas in the femtocell is provided with an Radio Frequency Identification (RFID) tag. Over the last few years, RFID tags have been implemented in a wide variety of applications. Radio Frequency Identification (RFID) tags contain circuitry that gains power from radio waves emitted by readers in their vicinity. The RFIDs use this power to transmit a unique identifier to the respective readers. One of the important applications is the localisation for mobile devices, as it is appreciated that location context can provide important information for the interpretation of RFID readings.

The RFID tags therefore allow each antenna's location or ID to be provided. Each of the UEs operating within the femtocell is also provided with an RFID tag. The HNB is accordingly provided with a RFID reader to communicate with the RFID tags in order to obtain location information of the distributed antennas and the UEs.

An exemplary method according to an embodiment of the invention will be described with reference to the flowchart of figure 7. The method commences upon network entry (i.e. when a user/subscriber has installed the femtocell base station) with an initialisation process including a I-INB obtaining the location information -or location identity (ID) of the distributed antennas. In step 200, the HNB uses the obtained information to create a "look-up" table which serves as a map indicating the location of the distributed antennas within the femtocell, It is noted that the look up table of the antennas location can be established either automatically or manually.

The antenna localisation can be performed either at the HNB or the UE (step 202).

If the antenna localisation is performed at the HNB, the HNB will determine the location of the UE using the centralised antenna to perform reference signalling and control with the UE (step 204). In response to the reference signalling, the UE, by means of the RFID tag, transmits its location information to the HNB.

Essentially, the HNB applies RFID localisation to locate the UE(s) and configure the antennas(s) of the UE(s). The HNB performs a feedback procedure to check for radio resource and antenna availability, determine the configuration on both transmission and antenna, and to receive feedback from the UE(s) to ensure that the configuration(s) is right for the UE(s). In order to achieve this, the HNB broadcasts the configuration and receive feedback(s) from the UE(s).

Once the HNB has determined the location of the UE, the HNB maps the location of the UE with the information in the lookup table. Essentially, the HNB maps the location of the UE with the location ID of the distributed antennas and decides which of the distributed antenna are to be switched on in order to support the UE (step 205). The HNB performs a check on availability of the radio resources and antennas, and determine the configuration on both transmission and antenna in step 206. In step 216, the HNB communicates with the selected distributed antenna(s), using mmWave or powerline connection as described above, and requests the selected antenna(s) to be switched on.

If the antenna localisation is performed by the UE, the UE detects antenna(s) in its vicinity and determines the most suitable distributed antenna(s) for data transmission (step 208). In this configuration, each of the UE is provided with an RFID reader to determine the location of these antennas. The decision to select the most suitable antenna(s) may be, for example, based on the distance between the UE and the antenna(s).

Accordingly, the UE communicates the decision to the HNB via the signalling and control channel (step 210). The HNB then determines whether the selected antenna(s) are available for transmission and whether there are available radio resources to support the requested antenna configuration.

If the selected antenna(s) is able to support the data transmission, the HNB will perform a check on availability of the radio resources and antennas, and determine the configuration on both transmission and antenna. If the selected antenna(s) is not available, the HNB will recommend locating another antenna (or a set of antenna).

In step 216, the HNB communicates with the selected distributed antenna(s), using mmWave or powerline connection as described above, and requests the selected antenna(s) to be switched on.

Once the antenna(s) is switched on, data transmission is established between the HNB and the UE in step 218.

In step 220, the HNB determines whether the UE is moving. It will be appreciated that by means of RFID localisation, the movement of the UE can be updated in a timely manner. In this example, an antenna switching procedure is employed. The UE which is connected to a distributed antenna (or a set of distributed antennas), for example antenna set-i, moves along a certain direction into another sub-area covered by another distributed antenna (or another set of distributed antenna), for example antenna set-2.

The HNB detects the location and movement of the UE by means of REID signals transmitted from the UE. By mapping the location information provided by the UE and the location ID of the antennas in the lookup table, the HNB is able to determine that antenna set-2 is able to provide coverage in the sub-area in which the UE is currently located (step 222). Accordingly, the HNB communicates with the antenna set-2, by means of mmWave or powerline transmission described above, and switches antenna set-2 on (step 224). The HNB maintains the connectivity with antenna set-I until it is confirmed that the UE is fully covered by antenna set-2 (steps 226 to 230).

It will be appreciated that the movement of the UE is relatively slow in the femtocell.

Therefore, switching procedure can be carried out with causing disruption to the service. A number of power control procedures can be implemented during the transition from antenna set-I to antenna set-2. For ease of understanding, a number of examples of the power control procedures are provided as follows: 1. Power constraint is applied to the distributed antennas such that the total transmit power of the active distributed antennas is the same throughout the whole switching process. Under this condition, the transmit power of antenna set-I is decreased gradually as the UE moves into the new sub-area covered by antenna set-2. Accordingly, the transmit power of antenna set-2 is also increased gradually. This can be easily achieved since the movement of the UE is updated in a timely manner.

2. In this case, power constraint is not applied. Under this condition, both sets of antennas, antenna set-i and antenna set-2, are switched on with the same transmit power. Essentially, antenna set-2 is switched on with the same transmission condition as antenna set-i, while the transmit power of antenna set-I is gradually reduced as the UE gradually moves into the coverage area of antenna set 2. Antenna set-i will be switched off once the UE is fully covered by antenna set-2 in the respective sub-area.

The described embodiments provide a number of advantages compared to a conventional femtocell.

The antenna(s) is only switched on when a UE moves into the respective coverage sub-area. As a result, less power is transmitted, thereby reducing/eliminating potential interference.

It is well-known that the path-loss of a signal can be expressed as: 4zdfJ2 (4) where d is the distance in metre, f is the radio frequency and the c is the speed of light in a vacuum.

The path loss can be represented by a path loss exponent. In equation (4) the path loss exponent is 2, which represents free-space path loss. As shown in figure 8, the path loss of the signal increases over distance, An example of direct comparison is that there is a 10 dB difference between a UE which is 3 metres from the antenna point and a UE which is 10 metre from the antenna point.

It is well-known to the skilled person that in a typical wireless communications environment, the value of the path loss exponent is normally in the range of 2 to 4.

However, in some environments, such as buildings and indoor environments, the path loss exponent can reach values in the range of 4 to 6. As shown in Figure 8, the path loss increases considerably with distance for a path loss exponent value 6. It is noted that there is a 30 dB difference between 3m and lOm.

In a hostile environment where the path loss is high, a high power transmission is required inside a coverage area. This could result in an increased in interference outside the coverage area. Therefore, an advantage provided by the embodiments of the invention is the ability to hand'e larger number of distributed antennas with a low transmission power within the boundary of the femtocell. This would eliminate any potential interference between neighbouring femtocells and/or macrocells. Thus, this will allow femtocell base stations of neighbouring femtocells to be installed substantially closed to each other without causing any interference to each other.

A further advantage of the embodiments of the present invention is that less power is wasted in overcoming penetration and shadowing losses. In addition, the line-of-sight channel provided between the selected active antenna(s) and the UE would also lead to reduced fade depths and delay spread in the channel.

Furthermore, services can be provided to different users through different antennas without causing interference.

While the foregoing specific description of an embodiment of the invention has been provided for the benefit of the skilled reader, it will be understood that it should not be read as mandating any restriction on the scope of the invention. The invention should be considered as characterised by the claims appended hereto, as interpreted with reference to, but not bound by, the supporting description.

Claims

CLAIMS: 1. A method of establishing communication between a wireless device and a further wireless device in a network, the wireless device comprises a set of antennas distributed in the network, wherein each of said set of antennas is configured to switch between an active state and an inactive state, the method comprising: obtaining, at the wireless device, location identity of a subset or whole of the entire set of antennas; obtaining location information of said further wireless device; selecting at least one of antennas for communication with said further wireless device based on said obtained location identity and said location information; switching said selected antenna to said active state; and wherein subsequent to said switching being performed, said wireless device is in communication with said further wireless device.
2. A method according to claim 1, wherein the step of obtaining location identity comprises receiving an RFID signal from said each of said set of antennas.
3. A method according to claim 1 or claim 2, wherein the step of obtaining location information of said further wireless device comprises receiving a further RFID signal from said further wireless device.
4. A method according to any one of the preceding claims, wherein the step of selecting comprises determining said at least one of said subset or set of antennas that are located in the vicinity of said further wireless device, based on said obtained location identity and said location information.
5. A method of establishing communication between a wireless device and a further wireless device in a network, the wireless device comprises a set of antennas distributed in the network, wherein each of said set of antennas is configured to switch between an active state and an inactive state, the method comprising: obtaining, at the wireless device, location identity of a subset or whole of the entire set of said antennas; obtaining, at the further wireless device, location identity of at least one of said set of antennas that are in the vicinity of the further wireless device, and sending said obtained location identity to the wireless device; selecting at least one of said at least one of said set of antennas based on said obtained location identity of said at east one of said antennas; switching said selected antenna to said active state; and wherein subsequent to said switching being performed, said wireless device is in communication with said further wireless device.
6. A method according to claim 5, wherein the step of obtaining location identity comprises receiving an RFID signal from said each of said set of antennas.
7. A method according to claim 5 or claim 6, wherein the step of sending said obtained location identity comprises transmitting an RFID signal from said further wireless device to said wireless device.
8. A method according to any one of the preceding claims, wherein the step of switching is performed via a millimetre-wave connection or a powerline connection.
9. A method according to any one of the preceding claims further comprising monitoring movement of the wireless device within said network by determining whether the further wireless device is in the vicinity of the selected antenna.
10. A method according to claim 9, further comprising obtaining a further location information of said further wireless device and selecting a further at least one of said subset or set of antennas based on said location identity and said obtained further location information if said wireless device is not in the vicinity of the selected antennas.
11. A method according to claim 9, further comprising obtaining, at the further wireless device, location identity of a further at least one of subset or set of said antennas that are in the vicinity of the wireless device, and sending said obtained location identity to the wireless device, and selecting, at the wireless device, at least one of said further at least one of subset or set of antennas based on said obtained identity if said further wireless device is not in the vicinity of the selected antenna.
12. A method according to claim 10 or claim 11, further comprising controlling transmit powers at the selected antenna and the selected further antenna.
13. A method according to any one of claims 10 to 12, further comprising switching the selected antenna to said inactive mode and switching the selected further antenna to said active mode.
14. A system for establishing communicafion between a wireless device and a further wireless device in a network, said wirels device comprises a set of antennas distributed in the network, wherein each of said set of antennas is configured to switch between an active state and an inactive state, the system comprising means for obtaining a location identity of a subset or whole of the entire set of antennas; means for obtaining location information of said further wireless device; means for selecting at least one of said antennas for establishing communication between said wireless device and said further wireless device; switching means for switching said selected antennas to said active mode; and wherein subsequent to said switching being performed, said wireless device is in communication with said further wireless device.
15. A system for establishing communication between a wireless device and a further wireless device in a network, the wireless device comprises a set of antennas distributed in the network, wherein each of said set of antennas is configured to switch between an active state and an inactive state, the system comprising: means for obtaining a location identity of a subset or whole of the entire set of said antennas; means for obtaining location identity of at least one of said set of antennas that are in the vicinity of the further wireless device, and sending said obtained location identity to the wireless device; means for selecting at least one of said at least one of said set of antennas based on said obtained location identity of said at least one of said antennas; switching means for switching said selected antenna to said active state; and wherein subsequent to said switching being performed, said wireless device is in communication with said further wireless device.
16. An apparatus for establishing communication with a wireless device in a network, the apparatus comprises a set of antennas distributed in the network, wherein each of said set of antennas is configured to switch between an active state and an inactive state, the apparatus further comprising: means for obtaining location identity of a subset or whole of the entire set of antennas; means for obtaining location information of said wireless device; means for selecting at least one of said antennas for communication with said wireless device based on said obtained location identity and said location information; switching means operable to switch said selected antenna to said active state, wherein subsequent to said switching being performed, said apparatus is in communication with said wireless device.
17. An apparatus according to claim 16, wherein said means for obtaining location identity comprises an RFID receiver configured to receive REID signals from said each of said set of antennas.
18. An apparatus according to claim 16 or claim 17, wherein said means for obtaining location information comprises a further RFID receiver configured to receive RFID signals from said wireless device.
19. An apparatus according to any one of claims 16 to 18, wherein said means for selecting is operable to determine said at least one of said subset or set of antennas that are located in the vicinity of said wireless device, based on said obtained location identity and said obtained location information.
20. An apparatus for establishing communication with a wireless device in a network, the apparatus comprises a set of antennas distributed in the network, wherein each of said set of antennas is configured to switch between an active state and inactive state, the apparatus further comprising: means for obtaining location identity of a subset or whole of the entire set of said antennas; means for receiving location identity information from said wireless device; means for selecting at least one of said at least one of said set of antennas based on said obtained identity of said at least one of said antennas; switching means for switching said at least one of said selected antennas to said active state, and wherein subsequent to said switching being performed, said apparatus is in communication with said wireless device.
21. An apparatus according to claim 20, wherein said means for obtaining location identity comprises an RFID receiver configured to receive an RFID signal from each of said set of antennas.
22. An apparatus according to claim 20 or claim 21, wherein said means for receiving comprises a further REID receiver configured to receive location identity information from said wireless device.
23. An apparatus according to any one of claims 16 to 22, wherein the switching means is operable to communicate with said set of antennas via a millimetre-wave connection or a powerline connection.
24. An apparatus according to any one of claims 16 to 23, further comprising means for monitoring movement of said wireless device within said network, said means for monitoring is configured to determine whether said wireless device is in the vicinity of the selected antennas.
25. An apparatus according to claim 24, wherein said monitoring means is operable to obtain location information of said wireless device and to select a further at least one of said subset or set of antennas based on said location identity and said obtained information if said wireless device is not in the vicinity of the selected antennas.
26. An apparatus according to claim 24, wherein said monitoring means is operable to receive location identity of a further at least one of subset or set of antennas that are in the vicinity of the wireless device, and selecting at least one of said further at least one of subset or set of antennas based on said obtained identity if said wireless device is not in the vicinity of the selected antennas.
27. An apparatus according to claim 25 or claim 26, further comprising power control means for controlling transmit powers at the selected antennas and the selected further antennas.
28. An apparatus according to any one of claims 25 to 27, wherein said switching means is further configured to switch the selected antennas to said inactive mode and to switch said selected further antennas to said active mode.
29. An apparatus for establishing communication with a wireless device in a network, the wireless device being provided with a set of antennas distributed throughout the network, wherein each of said set of antennas is configured to switch between an active and an inactive state, the apparatus comprising: means for transmitting location information of said apparatus to said wireless device.
30. An apparatus according claim 29, wherein said means for transmitting comprises an RFID tag.