GB2554912B - Wireless communication link management method, communication device and system - Google Patents

Description

WIRELESS COMMUNICATION LINK MANAGEMENT METHOD, COMMUNICATION DEVICE AND SYSTEM

FIELD OF THE INVENTION

The present invention relates in general to wireless transmission of data between a mobile node and receiving nodes over a high data rate communication link. In particular, the present invention provides a method for managing a wireless communication link established between a mobile node and a plurality of receiving nodes, all comprising a directional sector antenna. The present invention also provides a communication device and a communication system.

BACKGROUND OF THE INVENTION

AudioA/ideo applications using High Definition (HD) video or images are now increasingly numerous and require even higher data bit rates and higher quality of service.

For instance, a mobile source node (or device or station), such as a video camera or a Head Mounted Display (HMD) may exchange uncompressed HD data with a sink node (or device or station), such as a video storage (or display) device providing a high resolution image capturing facility or a Computer Graphic capable of adding virtual images to a video received from the HMD as a function of the location and the positioning of the HMD. Generally, for comfort and design reasons, such device is intended to be worn by the user preferably without physical link to any fixed node.

Therefore, a wireless network system using the millimetre wave frequency band (e.g., 60GHz) which enables freedom of movement without being hindered by cables is particularly well-adapted to the transmission of such uncompressed HD data, for example using a short distance technology defined in the 802.11 ad standard. The authorized band around a carrier frequency of 60GHz offers a wide bandwidth thus enabling a large quantity of data to be transmitted with a high data rate (>3Gbps). A typical characteristic of millimeter waves is the sensitivity to masking phenomena. Some static or moving obstacles such as furniture, objects, and human beings, can interrupt or disturb the communication link and thus cause transmission errors.

In order to reduce the impact of physical obstacles, wireless network systems comprising several fixed receiving nodes are considered. These receiving nodes may act as relay nodes between the mobile source node and the sink node. The sink node may be one of the receiving nodes, i.e. it may receive directly data from the mobile source node. The receiving nodes are spaced apart to create space diversity so that when an obstacle arises on the path between the mobile node and one of the receiving nodes, said obstacle has less chance to be also on the path between the mobile node and another receiving node. In practice, the receiving nodes are interconnected through a robust network, either using a wired communication technology as Ethernet or another wireless communication technology (such as defined in the 808.11 ac or 802.11 an standards).

Since 60GHz wireless propagation is subject to path losses (inherent to high frequency bands), the mobile and receiving nodes preferably use communication modules with directional antennas to compensate for attenuation. Such antennas may use beam forming techniques. They are typically steerable and can each generate a beam in a required direction or sector. In a variant, several high gain antennas may be used for communicating in several directions/sectors provided that antenna changes (sector sweep) can be made.

Thanks to the good directivity of these antennas, several wireless point-to-point connections may exist between the communication modules of the mobile node and of a given receiving node, each corresponding to different directions/sectors of the beams generated by the respective antennas. In other words, a point-to-point connection is defined by a pair of antennas and their respective directions/sectors.

In the case of a high data rate application such as required for video transmission (e.g. between 400 Mbps and 1 Gbps), the number of repetitions has to be small to fit the available bandwidth. For these purposes, when the mobile node moves in the coverage area of the wireless system, the best receiving nodes and the best antenna sectors to use (i.e. the best point-to-point connections) for the communication with the mobile node are determined as described in the 802.11 ad. In practice, the best point-to-point connection changes in the course of the movement of the mobile node due to the angle and the distance between antennas and due to the physical obstacles that may be located/arise on the path between them.

For instance, document WO 2016/018168 describes a method and system for beam alignment on directional wireless links. In this document, the determination of the best directional links is based on measurements of the reception/transmission quality, for instance measurements of the received signal strength (RSS), the signal-to-noise ratio (SNR) or the signal loss over a given channel.

For the sake of convenience, it is assumed that the trajectory of the mobile node is straight or at least practically linear. It should be noticed that any trajectory may be seen as a set of small linear portions.

It has been observed that when the mobile node moves in a direction which is orthogonal to the main/mean direction of the antenna sector(s) of a receiving node, many changes of antenna sectors occur during the movement of the mobile node and thus the link is unstable as its quality. These numerous antenna sector switches take time and generate a lot of traffic on the wireless network, thereby creating throughput overhead and decreasing the available network bandwidth.

Therefore, there is a need for improving existing methods of managing a wireless communication link between a mobile node and receiving nodes equipped with directional antennas. There is also a need for improving stability of the communication link and use of bandwidth.

SUMMARY OF THE INVENTION

The present invention has been devised to address one or more of the foregoing concerns.

In this context, according to a first aspect of the invention, there is provided a method for managing a wireless communication link established between a mobile node and a plurality of other nodes, the mobile node and each node of the plurality comprising a directional sector antenna, the method comprising: retrieving, for each node of the plurality, a number of antenna sector switches observed when transmitting data to the mobile node during a predetermined period of time; selecting a node from the plurality based on the retrieved number of switches; and setting a wireless point-to-point connection between the mobile node and the selected node.

Thanks to embodiments of the invention, the stability of the wireless communication link during the movement of the mobile node is improved over the prior art and the bandwidth usage is kept under control.

This is because the wireless point-to-point connection for exchanging data with the mobile node is selected by taking into account the antenna sector switches during the movement of the mobile node.

Optional features of the invention are further defined in the dependent appended claims.

According to embodiments, the selected node is the one having the smallest retrieved number of switches.

Thus, the number of switches is minimised and the quality of the wireless link is more stable.

According to embodiments, the method comprises a step of retrieving, for each node of the plurality, a value of at least one quality indicator representing the quality of the transmission of data during said predetermined period of time and the selecting of a node is also based on the retrieved quality indicator values.

According to embodiments, the quality indicator is a radio channel power indicator (RCPI), a signal-to-noise ratio (SNR), a bit error rate (BER) and/or a packet error rate (PER).

According to embodiments, the node may only be selected if its retrieved quality indicator value is above a first predetermined threshold.

According to embodiments, the node may only be selected if its retrieved quality indicator value is below a second predetermined threshold.

This allows the risk of instabilities to be decreased. This is because if the received power is very high, it means the mobile node is very close to the node and thus if the mobile node moves, there is a risk of a very high number of antenna sector changes in the next frame, thereby causing instabilities.

According to embodiments, the set wireless point-to-point connection operates at high data rate in the millimeter wave spectrum.

According to embodiments, the method comprises, for each node of the plurality, incrementing a counter by a first number when an antenna sector switch is observed during a time slot and decrementing the counter by a second number when no antenna sector switch is observed during a time slot, the second number being larger than the first number. A slow increase of the counter and a quick decrease of its value allow a good reactivity of the system.

Correspondingly, according to a second aspect of the present invention, there is provided a communication device for managing a wireless communication link established between a mobile node and a plurality of other nodes, the mobile node and each node of the plurality comprising a directional sector antenna, the communication device being configured for: retrieving, for each node of the plurality, a number of antenna sector switches observed when transmitting data to the mobile node during a predetermined period of time; selecting at least one node from the plurality based on the retrieved number of switches; and setting a wireless point-to-point connection between the mobile node and the at least one selected node.

According to a third aspect of the present invention, there is provided a communication system comprising a mobile node comprising a communication module equipped with at least one first directional antenna and a plurality of other nodes comprising communication modules equipped with second directional antennas adapted to communicate with said at least one first directional antenna through wireless point-to-point connections, wherein at least one of the nodes of the plurality is a communication device as aforementioned.

According to embodiments, some of the nodes of the plurality are fixed while others are mobile.

According to embodiments, the communication system implements a mixed-reality application, the mobile node is a head mounted display and the communication system comprises a sink node interconnected with the nodes of the plurality, the sink node being configured to generate virtual images based on real images received by the nodes of the plurality.

The communication device and system according to the second and third aspects have similar advantages and features as the method aforementioned.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be described, by way of example only, and with reference to the following drawings in which:

Figure 1 illustrates a communication system according to embodiments of the present invention;

Figure 2 illustrates steps of a method according to embodiments of the present invention;

Figure 3 illustrates steps for obtaining values of parameters according to embodiments of the present invention;

Figure 4 illustrates a use case of embodiments of the present invention; and

Figure 5 illustrates a possible architecture for a communication device according to embodiments of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

The invention is now described by means of specific non-limiting exemplary embodiments and by reference to the drawings.

Figure 1 illustrates a communication system according to embodiments of the present invention.

In the given example, a communication system 100 (e.g. a mixed reality system) comprises communication devices, in particular a mobile source node 101 and a sink node 102. The mobile source node 101 is for instance a mobile HMD (or a mobile camera), and the sink node 102 is for instance a server configured to merge “real” images coming from the mobile HMD 101 with computer-generated images to provide a mixed-reality application.

The communication system 100 also comprises a plurality of fixed nodes (communication devices, also called extenders) 103, 104, 105 and 106 that are respectively interconnected with the mobile node 101 through first point-to-point connections 107, 108, 109 and 110 belonging to a first wireless network 111 and with the sink node 102 through second point-to-point connections 112, 113, 114 and 115 belonging to a second network 116 (e.g. Ethernet).

The fixed nodes 103, 104, 105 and 106 act as relay nodes between the mobile node 101 and the sink node 102. As shown in the figure, they are spaced apart to create space diversity so that when an obstacle arises on the path between the mobile node 101 and one of the fixed nodes 103, 104, 105 and 106, said obstacle has less chance to be also on the path between the mobile node 101 and another fixed node acting as a relay node with the sink node 102. For instance, the fixed nodes 103, 104, 105 and 106 may be installed at each corner of a room.

According to other embodiments (not shown), the system may comprise mobile relay nodes having the same mobile capability as the HMD. The mobile relay nodes can move and have communication means allowing communication with other mobile relay nodes and the fixed nodes.

In the following description, what is described for the fixed nodes can be easily applied to mobile relay nodes by the person skilled in the art. A communication link between the mobile node 101 and the sink node 102 can thus be established using a path (or route) consisting of a first point-to-point connection between the mobile node 101 and a relay node 103, 104, 105 or 106, and of at least one second point-to-point connection between the relay node 103, 104, 105 or 106 and the sink node 102.

In this example, the sink node does not directly communicate with the mobile node, but through the relay nodes. However, embodiments are not limited thereto. For instance, in some embodiments (not shown), the sink node may be equipped with an antenna as for the relay nodes and communicate directly with the mobile node 101 through this means as a receiving node. The sink node may also be connected to a peripheral having such communication means, through USB or PCI-e bus or Ethernet.

In practice, the sink node 102 has at least as many network interfaces as the number of fixed nodes 103, 104, 105 and 106 (here four). Alternatively, the fixed nodes 103, 104, 105 and/or 106 are linked to a switch (not shown) which is also linked to the sink node 102. In this case, the sink node 102 may possibly have fewer network interfaces than the number of fixed nodes.

In a variant (not shown), the second network 116 may be wireless. For instance, the second network 116 may be compliant with the 802.11ac standard or the 802.11η standard, with a Gigabit throughput.

The first network 111 is preferably operating at a high data rate in the millimeter wave spectrum. For example, the first network is a 60 GHz wireless network such as specified in the 802.11ad standard. In some contexts, the first point-to-point connections may be called radio paths or directional Multigigabit communications.

For these purposes, the mobile node 101 comprises a communication module (not shown) equipped with at least one first directional antenna having a plurality of sectors (not shown). The fixed nodes 103, 104, 105 and 106 also each comprise a communication module (not shown) equipped with at least one second directional antenna having a plurality of sectors, adapted to communicate with said at least one first directional antenna of the mobile node 101.

For illustration purposes only, the sets of three lobes attached to the fixed nodes 103 to 106 (one of which is referenced 103a) represent three sectors of these fixed nodes. Obviously, more than three sectors can be defined and the embodiments are not limited to this example. In practice, there is an overlap between two neighboring sectors of an antenna.

The mobile node 101 moves in a limited area, under the coverage of the fixed nodes 103, 104, 105 and 106. The first network allows data transmissions to be performed with different data rates as a function of the distance between the mobile node 101 and the fixed nodes 103, 104, 105 and 106, and as a function of the Modulation and Coding scheme (MCS) used between them.

In the context of the present invention, a multiple path communication link is established between the mobile source node 101 and the sink node 102. This multiple path comprises a plurality of individual paths. Each individual path comprises a first point-to-point connection (e.g. 107, 108, 109 or 110) in the first wireless network 111 and a second point-to-point connection (e.g. 112, 113, 114 or 115) in the second network 116. In this example, the sink node 102 is in charge of selecting the best individual paths. However, embodiments of the present invention are not limited thereto. For instance, one of the fixed nodes can be in charge of selecting the best individual paths.

According to embodiments, this selection takes into account the stability of the first point-to-point connection. This is achieved notably by considering the number of sector switches of the antennas of the different fixed nodes 103, 104, 105 and 106 that are observed during a same amount of time.

In the example of Figure 1, only two networks are represented. However, the present invention is not limited thereto and the communication system may comprise more than two networks.

Figure 2 represents steps of a method according to embodiments of the present invention. These steps may be performed by one of the nodes of the communication system shown in Figure 1, preferably at the sink node 102 or at one of the fixed nodes 103, 104, 105 and 106. In the following description, the algorithm is described as being performed at the sink node (server) 102, but the skilled person can easily adapt the following description to apply it to one of the fixed nodes 103, 104, 105 and 106. According to preferred embodiments, it is proposed to retrieve, for each receiving node, a number of antenna sector switches observed when transmitting data to the mobile node during a predetermined period of time. Then, one (or more) receiving node is selected based on the retrieved number of switches. Finally, a wireless point-to-point connection is set between the mobile node and the selected receiving node. An exemplary implementation is described below. At step 201, the server 102 retrieves, for each of the fixed nodes 103, 104, 105 and 106, the number of antenna sector changes during a predetermined time slot. For instance, this time slot is defined by a predetermined number of beacon intervals (or super-frames), for instance 3 beacon intervals.

It is recalled that a beacon interval is defined as a regular (periodical) transmission period set for all the nodes communicating though the first wireless network 111. It notably comprises a “scan” time interval corresponding to the duration of an evaluation phase called antenna sweep phase during which a switch of antenna sector may occur. For example, this is done using a low data rate transmission Modulation and Coding scheme. In the 802.11 ad standard, this phase is called Sector Level Sweep (SLS). Thus, during one beacon interval, there may be at most one switch (or zero if the sector does not finally change).

In a variant, the time slot is based on a time-out counter, starting at Tmax, for example at 300ms, decreasing until zero and restarting at 300ms.

Optionally, the server 102 may also retrieve the value of quality indicator(s). The quality indicator is preferably the RCPI (Received Channel Power Indicator). The SNR (Signal-to-Noise Ratio), the BER (Bit Error Ratio) and/or PER (Packet Error Rate) may also be retrieved.

Details on how these parameters (number of antenna sector changes, RCPI) can be obtained are provided in the description of Figure 3.

At step 202, the server 102 selects the fixed node having the smallest number of antenna sector changes.

Optionally, it may also take into consideration the quality indicators. For instance, the server 102 may set a minimum RCPI value under which the fixed nodes are discarded. In this case, a fixed node having a too low RCPI value cannot be selected, even if it has the smallest number of antenna changes. In practice, the minimum RCPI may be defined so as to have a PER < 1%.

In a variant, the server 102 may set both a minimum RCPI value and a maximum RCPI value. This is because if the received power is very high, it means that the mobile node 101 is very close to the fixed node and thus if the mobile node moves, there is a risk of a very high number of antenna sector changes in the next coming frame, thereby causing instabilities.

At step 203, the server 102 determines a preferred path (or route) comprising a first point-to-point connection between the mobile node 101 and the selected fixed node (and a second point-to-point connection between the selected fixed node and the server 102). This first point-to-point connection is the most stable wireless link in the first network 111, or at least the most stable among the links meeting the RCPI condition(s).

Figure 3 shows steps for obtaining values of parameters such as the number of antenna sector changes or RCPI that are retrieved at step 201 according to embodiments. These steps may be performed by one of the nodes of the communication system shown in Figure 1, preferably one of the fixed nodes 103, 104, 105 and 106 or each of them. The following steps are preferably performed sequentially for each received frame.

At step 301, the current identifier of the active antenna sector of each fixed node is retrieved. This identifier is indicated in a specific field of the frame, as defined in the 802.11 ad standard.

Optionally, the RCPI (and possibly other quality variables) is measured for each fixed node.

At step 302, this current identifier of each fixed node is compared to the identifier of the active antenna sector of the corresponding fixed node stored for the previous frame.

If these identifiers are the same, at step 303, a variable called “ANTCONFIG number” is decreased by one, unless it is equal to zero (in this case it remains zero). This indicator represents the number of antenna sectors changes due to the mobile node displacements.

In a variant, at step 303, the variable may be decreased by two if its current value is equal to a predetermined maximum number. For instance, this maximum number may correspond to the number of beacon intervals in the time slot (or an arbitrary number of frames) which is set at the set-up of the system.

In another variant, at step 303, the variable may be set to zero.

If these identifiers are different, at step 304, the variable ANT-CONFIG number is increased by one, unless it is equal to the predetermined maximum number.

In this case, i.e. if the variable ANT-CONFIG has reached the predetermined maximum number, the value of this variable is not changed, i.e. it is let to the maximum number.

It should be noted that without fixing a maximum, after a lot of antenna sector changes, the value of the ANT-CONFIG number will be very high. As a consequence, it will take a while (i.e. numerous time slots) to reach the moment when the corresponding fixed node is the one having the smallest ANT-CONFIG number and is thus selected.

This is why a slow increase of the ANT-CONFIG number (one by one) and a rapid decrease of this number (by more than one) is advantageous and allow a good reactivity of the system.

Then, at step 305, the current value of the ANT-CONFIG number is saved. If measured, the value of the RCPI is also saved.

The value of these parameters may be centralized in the memory of the server 102 or in one of the fixed nodes 103, 104, 105 or 106, or in a variant they can be stored in each fixed node 103, 104, 105 and 106. They can be exchanged on the first wireless network 111 and/or second network 116 and are refreshed at least at each new time slot, as mentioned before.

In some embodiments, the values of these parameters may be stored in a table, as follows:

In a preferred embodiment, the table is stored in a fixed node (“master”) or in the server 102.

In practice, the exemplary algorithm described with reference to Figure 3 is performed for each frame (or super-frame, or time slot).

Figure 4 illustrates a use case of embodiments of the present invention. Embodiments of the present invention are not limited to this use case which is only provided for illustrative purposes.

For instance, automobile manufacturers have introduced Augmented Reality technologies into their showrooms, to provide customers with a more hands-on approach when purchasing a vehicle. A Mixed Reality (or hybrid reality) application allows real and virtual images to be merged for producing new environments and visualizations wherein physical and digital objects coexist and interact in real-time.

In this use case, a car manufacturer showroom 400 is considered. In this showroom, there is a full-size vehicle mock-up 401.

A customer (not shown) wearing a wireless HMD (mobile node, not shown) walks along a path 402 (in dash line) around the vehicle mock-up 401. By moving around the mock-up 410, the customer sees the car displayed on the HMD from all angles as if it were a real car. Such an application is useful for instance for design considerations, technical checking, or demonstration to customers before any manufacturing of the product.

The path 402 goes from the room entrance 403 to the seat 404 of the vehicle mock-up 401. Several fixed nodes 405, 406, 407, 408 and 409 are set-up in the showroom 400 to relay the data from and to the Mixed Reality server (sink node, not shown).

According to embodiments of the present invention, the Mixed Reality server (sink node) selects in real time the fixed nodes and their antenna sectors to use for data exchanges with the HMD (mobile node) so that they follow the displacement direction of the HMD. Thus, in this example, on a first segment 410 of the path 402, the fixed node 409 and its antenna sector 409a in line with the segment are selected because fewer sector changes occur and thus the communication link is more stable. On a second segment 411 of the path 402, the fixed node 406 and its antenna sector 406a are selected because fewer sector changes occur and thus the communication link is more stable. And finally, on the third segment 412 of the path 402, the fixed node 405 and its antenna sector 405a are selected because fewer sector changes occur and thus the communication link is more stable.

Thanks to the invention, the link stability is improved compared to the prior art. Indeed, in the prior art, the closest fixed node (with the highest RCPI) would be selected (here, fixed node 405) for the whole path, and numerous sector changes would be observed due to the angle between the direction of the path, notably on the segment 411, and the main/mean direction of its antenna sectors.

According to other embodiments (not shown), the system may comprise mobile relay nodes having the same mobile capability as the HMD. The mobile relay nodes can move and have communication means allowing communication with other mobile relay nodes and the fixed nodes.

Figure 5 illustrates a possible architecture for a communication device or node 500 according to embodiments of the present invention, such as nodes 101, 103, 104, 105 and 106 shown in Figure 1.

In this exemplary architecture, the communication device 500 comprises a communication bus 510 to which there are connected: a micro-controller or Control Process Unit (denoted CPU) 501; a Read-Only Memory (denoted ROM) 502 in which instructions for implementing steps of a method according to embodiments may be stored; a Random Access Memory (denoted RAM) 503, working as a main memory, in which instructions and temporary variables and parameters for implementing steps of a method according to some embodiments may be loaded from a non-volatile memory, and whose capacity may be extended by an additional Random Access Memory connected to an expansion port (not shown); a first communication interface 508, preferably wireless, enabling first point-to-point connections with the other wireless communication devices through the first network 111; and a second communication interface 518, wired (Ethernet for example) or wireless, enabling second point-to-point connections with at least some of the communication devices (here nodes 102, 103, 104, 105 and 106) through the second network 116. It should be noted that this second communication interface 518 is optional for the mobile node 101.

The communication bus 510 provides communication and interoperability between the various elements included in the communication device 500 or connected to it. For instance, the CPU 501, the RAM 503, the ROM 502 and the communication interface(s) 508, 518 exchange data and control information via the communication bus 510. The representation of the bus is not limiting and in particular the CPU 501 is operable to communicate instructions to any element of the communication device 500 directly or by means of another element of the communication device 500.

After the communication device 500 has been powered on, the CPU 501 is capable of executing, from the RAM 503, instructions pertaining to a computer program, once these instructions have been loaded from the ROM 502 or from an external memory (not shown in Figure 5). A computer program of this kind causes the CPU 501 to perform some or all of the steps of the algorithms described with reference to Figures 2 and 3.

In embodiments, the CPU 501 controls the overall operation of the communication device 500. It acts as a data analyser unit, which analyses useful data payload (also referred as MAC payload) of a packet received from another communication device, either received through 60 GHz wireless network (first network 111) and processed by the first wireless communication interface 508, or received through the second network 116 and processed by the second communication interface 518.

The first communication interface 508 comprises: a Wireless Physical Layer Module (denoted WPHY) 507; a Medium Access Controller (denoted MAC) 506; at least one antenna 530 (here, only one antenna is represented but the present invention is not limited thereto), for instance a directional antenna or several high gain antennas configured to communicate in several different directions.

The WPHY 507 is configured for processing a signal output by the MAC 506 before it is sent out through the antenna 530. For example, the processing comprises modulation, frequency transposition and power amplification processes. In embodiments, the WPHY 507 may also be configured for processing a signal received by the antenna 530 before it is provided to the MAC 506.

The MAC 506 manages access to the wireless medium (first network 111). It is also configured as a synchronization control unit, which controls the synchronization of data for scheduling the transmissions through the first network 111, based on a beacon interval. More specifically, the MAC 506 schedules the beginning and the end of an emission of data by the antenna 530, through the first network 111, as well as the beginning and the end of a reception of data from the first network 111, by the antenna 530.

The antenna 530 supports Directional Multi Gigabit (DMG) data transfers. It is adapted to select a sector for transmitting and receiving signals. In a variant where there are several antennas 530, the antennas are configured to communicate in several different directions, i.e. to transmit and receive signals in different sectors.

The second communication interface 518 comprises: a Physical Layer Module (denoted PHY) 517; a Medium Access Controller (denoted MAC) 516; an interface connection 540, for example comprising a physical cable (if the second network 116 is wired) or an antenna (if the second network 116 is wireless).

The PHY 517 is configured for processing a signal output by the MAC 516 before it is sent out through the interface connection 540. For example, the processing aims at adapting the signal to the electrical specification and to the access mode of the interface connection 540. In embodiments, the PHY 517 may also be configured for processing a signal received by the interface connection 540 before it is provided to the MAC 516, for instance according to the IEEE 802.3 (Gigabit Ethernet)

The communication device 500 may be connected to an external source or device through the interface 520, and may exchange data with it. The external source or device may execute an application generating application data, such as a compressed video stream, a file storage output, a video camera output, or data to be displayed.

The communication device 500 comprises a video application module 505 configured to convert these application data in packets suitable for being transmitted over a network (e.g. first wireless network 111). The module 505 is thus configured to packetize the application data and transmits the packets to a Link Layer Controller (LLC) 504. In embodiments, the module 505 is also configured to convert the received packets from the LLC 504 into application data to be transmitted through the interface 520.

In preferred embodiments, the data packets managed by the module 505 are TCP/IP or UDP/IP video lossless compressed data with a data rate around 100 to 400 Mbps.

The LLC 504 is configured to establish the link between the mobile node 101 and the fixed nodes 103, 104, 105 and 106, in order to transmit and receive the packets between the video application module 505 and the communication interfaces 508 and/or 518.

Although the present invention has been described hereinabove with reference to specific embodiments, the present invention is not limited to the specific embodiments, and modifications which lie within the scope of the present invention will be apparent to a person skilled in the art. Many further modifications and variations will suggest themselves to those versed in the art upon making reference to the foregoing illustrative embodiments, which are given by way of example only and which are not intended to limit the scope of the invention as determined by the appended claims. In particular different features from different embodiments may be interchanged, where appropriate.

Claims (12)

1. A method for managing a wireless communication link established between a mobile node and a plurality of other nodes, the mobile node and each node of the plurality comprising a directional sector antenna, the method comprising: retrieving, for each node of the plurality, a number of antenna sector switches observed when transmitting data to the mobile node during a predetermined period of time; selecting a node from the plurality based on the retrieved number of switches; and setting a wireless point-to-point connection between the mobile node and the selected node.

2. A method according to claim 1, wherein the selected node is the one having the smallest retrieved number of switches.

3. A method according to claim 1 or 2, comprising a step of retrieving, for each node of the plurality, a value of at least one quality indicator representing the quality of the transmission of data during said predetermined period of time and wherein the selecting of a node is also based on the retrieved quality indicator values.

4. A method according to claim 3, wherein the quality indicator is a radio channel power indicator (RCPI), a signal-to-noise ratio (SNR), a bit error rate (BER) and/or a packet error rate (PER).

5. A method according to claim 3 or 4, wherein the node may only be selected if its retrieved quality indicator value is above a first predetermined threshold.

6. A method according to claim 5, wherein the node may only be selected if its retrieved quality indicator value is below a second predetermined threshold.

7. A method according to any one of the preceding claims, wherein the set wireless point-to-point connection operates at high data rate in the millimeter wave spectrum.

8. A method according to any one of the preceding claims, comprising, for each node of the plurality, incrementing a counter by a first number when an antenna sector switch is observed during a time slot and decrementing the counter by a second number when no antenna sector switch is observed during a time slot, the second number being larger than the first number.

9. A communication device for managing a wireless communication link established between a mobile node and a plurality of other nodes, the mobile node and each node of the plurality comprising a directional sector antenna, the communication device being configured for: retrieving, for each node of the plurality, a number of antenna sector switches observed when transmitting data to the mobile node during a predetermined period of time; selecting at least one node from the plurality based on the retrieved number of switches; and setting a wireless point-to-point connection between the mobile node and the at least one selected node.

10. A communication system comprising a mobile node comprising a communication module equipped with at least one first directional antenna and a plurality of other nodes comprising communication modules equipped with second directional antennas adapted to communicate with said at least one first directional antenna through wireless point-to-point connections, wherein at least one of the nodes of the plurality is a communication device according to claim 9.

11. A communication system according to claim 10, wherein some of the nodes of the plurality are fixed while others are mobile.

12. A communication system according to claim 11 or 12, implementing a mixed-reality application, wherein the mobile node is a head mounted display and the communication system comprises a sink node interconnected with the nodes of the plurality, the sink node being configured to generate virtual images based on real images received by the nodes of the plurality.