WO2024007210A1

WO2024007210A1 - Smart antenna for optical network terminals and indoor optical network

Info

Publication number: WO2024007210A1
Application number: PCT/CN2022/104202
Authority: WO
Inventors: Francis KESHMIRI; Hao XIONG; Zhixiong REN
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2022-07-06
Filing date: 2022-07-06
Publication date: 2024-01-11

Abstract

This disclosure relates to optical network terminals (ONTs) for indoor optical networks, particularly, optical network terminals that provide Wi-Fi services at indoor serving locations. A master access device of this disclosure is provided for an indoor optical network, whereby the indoor optical network comprises one or more slave access devices optically coupled to the master access device. Each slave access device comprises at least one transceiver and at least two antenna elements operably coupled to the at least one transceiver in a switchable manner. In this regard, the master access device is configured to assess one or more parameters of a radiated or received radio frequency (RF) signal from each slave access device and to switch the at least two antenna elements of the slave access device based on the one or more parameters.

Description

SMART ANTENNA FOR OPTICAL NETWORK TERMINALS AND INDOOR OPTICAL NETWORK

TECHNICAL FIELD

The present disclosure relates to optical network terminals (ONTs) for indoor optical networks, such as an on-premises passive optical network (PON) based on Fiber-to-the-room (FTTR) networking technologies, or to optical network terminals that provide Wi-Fi services at indoor serving locations.

BACKGROUND

Generally, FTTR networking technology is based on optical fiber communication, and therefore is capable of offering high-bandwidth and reliable transmission. The topology and functionality of FTTR technology depends on its implementation form, e.g., an implementation form based on the Fifth Generation Fixed Network (F5G) may include services to consumers and enterprises with assist of wireless technologies primarily by Wi-Fi, and focuses on optical fiber elements up to the connection serving locations such as individual users, homes, offices, and the like.

In an on-premises PON, Wi-Fi connectivity may be provided by home area architecture based on fiber point-to-multipoint and with backhaul from a central office and/or an optical line terminal (OLT) , thereby forming a FTTR to home (FTTR-2H) scenario. In a general scenario, especially to allow fiber connection and backhauling for access networking, FTTR may connect a Primary ONT to several secondary or Edge ONTs over fiber. Compared to a main access point (AP) of a legacy Wi-Fi scenario, the FTTR based solution particularly improves Wi-Fi coverage in the locations far from the main AP.

Typically, the desktop Edge ONTs are realized as wall mounted products that are to be installed on the wall or be used instead of power outlets, inside a room. As such, the localization, topology, as well as performance of such Edge ONTs may vary depending on indeterministic factors such as fiber routing, e.g. from the Primary ONT to the respective Edge ONTs, static objects and/or reflective surfaces, e.g. walls and furniture, non-ideal positioning, e.g. caused by installation diversity and imitations, and infrastructure of the installed locations, e.g. building status and local building regulations.

SUMMARY

In view of the above, this disclosure aims to provide an improved master access device, an improved indoor optical network and a method. An objective is to facilitate beam switching in slave access devices to make performant radiation in front hemisphere, especially for addressing the above-mentioned limitations.

These and other objectives are achieved by the embodiments of this disclosure as described in the independent claims. Advantageous implementations are further defined in the dependent claims.

According to a first aspect of this disclosure, a master access device for an indoor optical network is provided. The indoor optical network comprises one or more slave access devices optically coupled to the master access device. Each slave access device comprises at least one transceiver and at least two antenna elements operably coupled to the at least one transceiver in a switchable manner. The master access device is configured to assess one or more parameters of a radiated or received radio frequency (RF) signal from each slave access device and to switch the at least two antenna elements of the slave access device based on the one or more parameters.

The one or more parameters of the radiated or received radio frequency signal may comprise at least one of a radio transmit power, an effective isotropic radiated power (EIRP) , a received signal strength indicator (RSSI) , a signal to noise ratio (SNR) , and a front to back ratio (FBR) , e.g. a ratio of power or signal strength radiated in the front or main radiation lobe to that radiated in the opposite direction, e.g. 180 degrees from the main lobe.

Therefore, this disclosure presents a smart antenna solution to adapt the coverage directions and signal strengths of the slave access devices for a robust performance, e.g. a robust Wi-Fi performance, against environment, thereby facilitating accurate and stable service coverage less dependent on the installation locations of the slave access devices. Furthermore, due to the switching of the radiation directions of the antenna elements for a given RF stream, especially by switching the antenna elements of the slave access devices, the effective radiation coverage of the slave access devices at a serving location can be advantageously maximized.

In an implementation form of the first aspect, the master access device is configured to switch the at least two antenna elements sequentially at a regular interval.

Therefore, the coverage of each slave access device can be advantageously enhanced. For instance, if one or more parameters of the radiated or received signals corresponding to the antenna elements at respective radiation directions are within an acceptable limit, the slave access device can be configured to radiate or receive signals in all acceptable directions for a given RF stream by switching the antenna elements sequentially.

In an implementation form of the first aspect, each slave access device comprises at least one further transceiver and at least two further antenna elements operably coupled to the at least one further transceiver in a switchable manner.

In this regard, the master access device is configured to assess the one or more parameters of the radiated or received radio frequency signal from each slave access device, and to switch the at least two antenna elements and the at least two further antenna elements of the slave access device based on the one or more parameters.

Advantageously, the master access device may implement the beam switching in a Multiple-Input-Multiple-Output (MIMO) configuration, e.g. a 2x2 MIMO configuration.

In an implementation form of the first aspect, the master access device is configured to switch the at least two antenna elements and the at least two further antenna elements of each slave access device simultaneously.

Alternatively, the master access device may be configured to switch the at least two antenna elements and the at least two further antenna elements of each slave access device sequentially at a regular interval.

Advantageously, the coverage of each slave access device can be further enhanced by configuring the slave access device to radiate or receive signals in all acceptable directions for the respective RF streams by switching the respective antenna elements for each respective RF stream simultaneously or sequentially.

According to a second aspect of this disclosure, an indoor optical network is provided. The indoor optical network comprises the master access device according to the first aspect of this disclosure, and the one or more slave access devices, whereby the one or more slave access devices are optically coupled to the master access device.

Therefore, an improved indoor optical network is provided that can be implemented to enhance the FTTR-2H technology by deploying the smart antenna solution for the slave access devices to achieve a location free installation solution for the slave access devices.

In an implementation form of the second aspect, each slave access device further comprises a phase shifter coupled between one of the at least two antenna elements and the at least one transceiver.

In this regard, the phase shifter can be a passive or active phase shifter. In addition, the phase shifter is configured to apply a phase shift by a predefined amount. Therefore, the at least two antenna elements can be configured to have phase shift of a predefined amount in order to tilt the beam by a predefined amount in front hemisphere, e.g. for an implementation with two beams per RF stream, the predefined tilted radiation beams can be toward thetas equal +30 degrees and -30 degrees respectively or similar angles.

Advantageously, the selection of tilted beams for a given RF stream of the slave access devices results in the reduction of interferences that may be caused between two neighboring slave access devices and/or from another source of electromagnetic interference.

In an implementation form of the second aspect, the at least two antenna elements of each slave access device are Microstrip antennas or patch antennas.

Advantageously, the slave access devices can be realized in a compact and a cost-effective manner.

In an implementation form of the second aspect, each slave access device comprises at least one further transceiver and at least two further antenna elements operably coupled to the at least one further transceiver in a switchable manner.

In this regard, the at least two further antenna elements of each slave access device may be Microstrip antennas or patch antennas. Furthermore, each slave access device comprises a further phase shifter coupled between one of the at least two further antenna elements and the at least one further transceiver.

In this regard, the further phase shifter is a passive phase shifter. In addition, the further phase shifter is configured to apply a phase shift by a predefined amount, for example, equal to the phase shift applied by the phase shifter.

Advantageously, the antenna elements can be configured to have a passive phase shift to tilt the beam in front hemisphere, thereby facilitating the selection of tilted beams for the respective RF streams of the slave access devices.

In an implementation form of the second aspect, the at least two antenna elements and the at least two further antenna elements of each slave access device are configured to radiate signal with polarizations orthogonal to each other.

In addition, each of the at least two antenna elements and of the at least two further antenna elements of each slave access device may be configured to radiate signal to cover a respective portion of front-hemisphere. For example, in an implementation with four antenna elements, each beam corresponding to an antenna element may cover one-fourth or a quarter of front hemisphere, i.e. a quarter-hemisphere beam.

Advantageously, a high isolation between the respective RF streams, as well as a high radiation diversity, can be achieved. Furthermore, a spatial distribution of the main beams corresponding to the RF streams can be achieved with a minimum of overlap, which may result in minimizing the combined gain as well as in maximizing the gain of individual antenna elements to limit the EIRP, e.g. according to band-specific EIRP regulations.

In an implementation form of the second aspect, each slave access device comprises a first printed circuit board layer comprising the at least two antenna elements and/or the at least two further antenna elements, and a second printed circuit board layer comprising the at least one transceiver and the phase shifter, and/or the at least one further transceiver and the further phase shifter.

In this regard, the first printed circuit board layer may be assembled on top of the second printed circuit board layer via one or more connectors, e.g. one or more RF spring contacts such as antenna clips.

Advantageously, for instance, the slave access devices can be realized in a simplified manner.

In an implementation form of the second aspect, at least one of the slave access devices has a package dimension of around 86 mm × 86 mm.

Advantageously, for instance, the slave access devices can be installed on or instead of conventional power outlets.

In an implementation form of the second aspect, the indoor optical network comprises two or more slave access devices.

In this regard, at least two of the slave access devices may be optically coupled to the master access device via an optical splitter. For instance, the optical splitter may comprise or be a fused biconical taper (FBT) splitter, a planar lightwave circuit (PLC) splitter, an arrayed waveguide grating (AWG) , or the like.

According to a third aspect of this disclosure, a method is provided for operating one or more slave access devices of an indoor optical network, each comprising at least one transceiver and at least two antenna elements operably coupled to the at least one transceiver in a switchable manner. The method comprises the steps of assessing one or more parameters of a radiated or received radio frequency signal from each slave access device by a master access device, and switching the at least two antenna elements of the slave access device based on the one or more parameters by the master access device.

According to a fourth aspect of this disclosure, a computer program is provided that comprises instructions which, when the program is executed by a processor of the master access device according to the first aspect of this disclosure, cause the processor to perform the method according to the third aspect of this disclosure or any implementation form thereof.

It is to be noted that the method according to the third aspect corresponds to the master access device according to the first aspect and the indoor optical network according to the second aspect, and their implementation forms. Accordingly, the method of the third aspect may have corresponding implementation forms. Further, the method of the third aspect achieves the same advantages and effects as the master access device of the first aspect and the indoor optical network of the second aspect, and their respective implementation forms.

BRIEF DESCRIPTION OF THE DRAWINGS

The above described aspects and implementation forms will be explained in the following description of specific embodiments in relation to the enclosed drawings, in which:

Fig. 1 shows a first exemplary embodiment of an indoor optical network, an exemplary embodiment of a master access device, and a first exemplary embodiment of a slave access device;

Fig. 2 shows a second exemplary embodiment of the slave access device;

Fig. 3 shows a third exemplary embodiment of the slave access device;

Fig. 4 shows a fourth exemplary embodiment of the slave access device;

Fig. 5 shows simulation results for normalized far-field directivities of the slave access device in polar form;

Figs. 6A-6D show four exemplary beam directions of the slave access device;

Fig. 7 shows exemplary return loss and port isolations of the slave access device;

Fig. 8 shows a second exemplary embodiment of the indoor optical network;

Fig. 9 shows an exemplary implementation of the indoor optical network for different indoor serving locations; and

Fig. 10 shows an exemplary flow diagram of the method according to an embodiment of this disclosure.

DETAILED DESCRIPTION OF EMBODIMENTS

Reference will now be made in detail to exemplary embodiments of the present disclosure, which are illustrated in the accompanying drawings. However, the following embodiments of the present disclosure may be variously modified and the range of the disclosure is not limited by the following embodiments. Reference signs for similar entities in different embodiments are partially omitted.

In Fig. 1, a first exemplary embodiment of an indoor optical network 100, especially comprising an exemplary embodiment of a master access device or a Primary optical network terminal (ONT) 110, and a first exemplary embodiment of a slave access device or a slave or Edge optical network terminal (ONT) 130, is illustrated. The slave access device 130 is optically coupled to the master access device 110 via a hybrid fiber with electrical and optical links 120.

The master access device 110 may comprise a processing and control unit (CPU) 111, a transceiver 112, and a switch control signal generation circuit (SWC) 113. The SWC 113 can be realized as a separate entity or can be realized within the CPU 111 integrally. The transceiver 112 is primarily configured to transmit one or more radio frequency streams RF to the slave access device 130 via the hybrid fiber link 120.

The transceiver 112 is further configured to receive a signal from the slave access device 130, e.g. corresponding to a received radio frequency signal, and to convey the received signal to the CPU 111 for further processing. The CPU 111 may process the received signal, especially to analyze or assess one or more parameters, including but not limited to transmit or received power, EIRP, RSSI, SNR, and FBR. Based on the assessment, the CPU 111, especially by means of the SWC 113, is configured to generate a switch control signal SC.

The slave access device 130 may comprise a transceiver 131, especially an optical transceiver, which is configured to receive at least one radio frequency stream RF from the transceiver 112 of the master access device 110 via the fiber optic link 120. The transceiver 131 is further configured to receive the switch control signal SC from the master access device 110 via the fiber optic link 120. The slave access device 130 may further comprise a switch (SW) 132 followed by two antenna feeding paths or feeds 133, 134.

The two antenna feeds 133, 134 may be respectively coupled to an antenna array (ANT) 136 having two antenna elements AE ₁, AE ₂, especially to the respective antenna elements AE ₁, AE ₂. In this regard, the antenna elements AE ₁, AE ₂ are configured to radiate or receive signals with polarizations orthogonal to each other, e.g. by means of orthogonal current flows. In this illustration, the antenna feed 133 is coupled to the antenna element AE ₁, and the antenna feed 134 is coupled to the antenna element AE ₂, however, via a passive phase shifter (PS) 135. The passive phase shifter 135 may be configured to apply a defined amount of phase shift so that the antenna feeds 133, 134, respectively the antenna elements AE ₁, AE ₂, have a defined amount of passive phase shift.

The switch 132 can be realized as a single-pole-double-through (SPDT) switch and is configured to receive the radio frequency stream RF from the transceiver 131 and to switch between the two antenna feeds 133, 134, e.g. to switch the transmission of the radio frequency stream RF between the two antenna feeds 133, 134. In this regard, the state of the switch 132 may be controlled or toggled by means of the switch control signal SC. The switch 132 can be realized as a cascaded entity between TRX 131 and antennas, or can be alternatively realized as a parallel entity which control TRX 131 without conveying RF signal to the antennas.

For instance, the master access device 110 may initiate a calibration scheme in order to calibrate the indoor optical network 100. In this regard, the master access device 110 may receive a signal or stream corresponding to a radio frequency signal received through the antenna element AE ₁ and the antenna feed 133, and a further signal or stream corresponding to a further radio frequency signal received through the antenna element AE ₂ and the antenna feed 134, e.g. by switching the antenna feeds 133, 134 alternatively via the switch 132.

The master access device 110, especially the CPU 111 of the master access device 110, may assess one or more signal parameters of the signal or stream and of the further signal or stream, especially to identify which of the two polarizations corresponding to the antenna elements AE ₁, AE ₂ is advantageous, and may accordingly toggle the switch 132 to maintain communication only via the antenna element with the advantageous polarization. In addition, if both antenna elements AE ₁, AE ₂ result in advantageous polarizations, the master access device 110 may switch the antenna elements AE ₁, AE ₂ at a regular interval, e.g. by toggling the switch 132 at a regular interval, to maintain communication via both antenna elements AE ₁, AE ₂.

In Fig. 2, a second exemplary embodiment of the slave access device 230 is illustrated. The slave access device 230 differs from the slave access device 130 in that the slave access device 230 may comprise a single-pole-multiple-through (SPNT) switch 232 followed by a number of N antenna feeds, and an antenna array 236 comprising a number of N antenna elements AE ₁-AE _N. The number of N antenna feeds may comprise a respective passive phase shifter PS ₁-PS _N, whereby each passive phase shifter PS ₁-PS _N may be configured to apply a defined amount of phase shift so that the number of N antenna feeds, respectively the number of N antenna elements AE ₁-AE _N have a defined amount of passive phase shift. Furthermore, the number of N antenna elements AE ₁-AE _N may be configured to radiate signals or beams at a respective part of the front hemisphere of the antenna array 236, for example, with a minimum overlap. The spatial division of front hemisphere of the antenna array 236 may be an arbitrary spatial division or an equal spatial division of the front hemisphere.

The master access device 110 may initiate a calibration scheme in order to calibrate the indoor optical network 100. In this regard, the master access device 110 may receive a number of N signals or streams corresponding to a number of N radio frequency signals received through the respective antenna elements AE ₁-AE _N, e.g. by switching the number of N antenna feeds alternatively via the switch 232. The master access device 110, especially the CPU 111 of the master access device 110, may assess one or more signal parameters of the number of N signals or streams, especially to identify which part of the front hemisphere of the antenna array 236 corresponding to the antenna elements AE ₁-AE _N is advantageous, and may accordingly toggle the switch 232 to maintain communication only via the advantageous antenna element.

In Fig. 3, a third exemplary embodiment of the slave access device 330 is illustrated. The slave access device 330 may comprise a first transceiver (TRX ₁) 131, corresponding to the transceiver of the slave access device 130, which is configured to receive a first radio frequency stream RF ₁ from the transceiver 112 of the master access device 110 via the fiber optic link 120. The first transceiver 131 is further configured to receive a first switch control signal SC ₁ from the master access device 110 via the fiber optic link 120.

In addition, the slave access device 330 may comprise a second transceiver (TRX ₂) 331, especially an optical transceiver, which is configured to receive a second radio frequency stream RF ₂ from the transceiver 112 of the master access device 110 via the fiber optic link 120. The second transceiver 331 is further configured to receive a second switch control signal SC ₂ from the master access device 110 via the fiber optic link 120.

The slave access device 330 may further comprise a first switch (SW ₁) 132, corresponding to the switch of the slave access device 130, that is configured to switch between a first antenna feed 133 and a second antenna feed 134. The first antenna feed 133 and the second antenna feed 134 may be respectively coupled to a first antenna array (ANT ₁) 136 comprising a first antenna element AE ₁ and a second antenna element AE ₂, especially to the first antenna element AE ₁ and the second antenna element AE ₂, respectively.

For instance, the first antenna feed 133 is coupled to the first antenna element AE ₁, and the second antenna feed 134 is coupled to the second antenna element AE ₂, however, via a first passive phase shifter (PS ₁) 135. The first passive phase shifter 135 may be configured to apply a defined amount of phase shift so that the first antenna element AE ₁ and the second antenna element AE ₂ have a defined amount of passive phase shift.

In addition, the slave access device 330 may further comprise a second switch (SW ₂) 332, that is configured to switch between a third antenna feed 333 and a fourth antenna feed 334. The third antenna feed 333 and the fourth antenna feed 334 may be respectively coupled to a second antenna array (ANT ₂) 336 comprising a third antenna element AE ₃ and a fourth antenna element AE ₄, especially to the third antenna element AE ₃ and the fourth antenna element AE ₄, respectively.

For instance, the third antenna feed 333 is coupled to the third antenna element AE ₃, and the fourth antenna feed 334 is coupled to the fourth antenna element AE ₄, however, via a second passive phase shifter (PS ₂) 335. The second passive phase shifter 135 may be configured to apply a defined amount of phase shift so that the third antenna element AE ₃ and the fourth antenna element AE ₄ have a defined amount of passive phase shift.

In this regard, the first antenna element AE ₁ and the second antenna element AE ₂ are configured to radiate or receive signals with polarizations orthogonal to each other, e.g. by means of orthogonal current flow. In addition, the third antenna element AE ₃ and the fourth antenna element AE ₄ are configured to radiate or receive signals with polarizations orthogonal to each other, e.g. by means of orthogonal current flow.

Additionally or alternatively, the first antenna element AE ₁, the second antenna element AE ₂, the third antenna element AE ₃, and the fourth antenna element AE ₄ are configured so that the first antenna array 136 and the second antenna array 336 radiate or receive signals with polarizations orthogonal to each other.

The first switch 132 may be realized as a single-pole-double-through (SPDT) switch and is configured to receive the first radio frequency stream RF ₁ from the first transceiver 131 and to switch between the first antenna feed 133 and the second antenna feed 134, e.g. to switch the transmission of the first radio frequency stream RF ₁ between the first antenna feed 133 and the second antenna feed 134. In this regard, the state of the first switch 132 may be controlled or toggled by means of the first switch control signal SC ₁.

Additionally, the second switch 332 may also be realized as a single-pole-double-through (SPDT) switch and is configured to receive the second radio frequency stream RF ₂ from the second transceiver 331 and to switch between the third antenna feed 333 and the fourth antenna feed 334, e.g. to switch the transmission of the second radio frequency stream RF ₂ between the third antenna feed 333 and the fourth antenna feed 334. In this regard, the state of the second switch 332 may be controlled or toggled by means of the second switch control signal SC ₂.

For instance, the first passive phase shifter 135 may provide a phase difference of 100 degrees between the first antenna element AE ₁ and the second antenna element AE ₂, which may cause the first antenna element AE ₁ and the second antenna element AE ₂ to tilt the respective beams to theta +30 degrees and -30 degrees in the front hemisphere. In addition, the second passive phase shifter 335 may provide a phase difference of 100 degrees between the third antenna element AE ₃ and the fourth antenna element AE ₄, which may cause the third antenna element AE ₃ and the fourth antenna element AE ₄ to tilt the respective beams to theta +30 degrees and -30 degrees in the front hemisphere.

Furthermore, the first antenna element AE ₁, the second antenna element AE ₂, the third antenna element AE ₃, and the fourth antenna element AE ₄ may be arranged to have orthogonal radiation polarization of 45 degrees, i.e. each antenna element may emit a quarter-hemisphere beam, which may result in a high isolation between the first radio frequency stream RF ₁ and the second radio frequency stream RF ₂, as well as a high radiation diversity with +45 degrees and -45 degrees polarization. Consequently, the front hemisphere can be spatially divided into four high-directive parts or sectors, and accordingly can be used, e.g. simultaneously at least two or more sectors, to perform localization in four spatial sectors in the front hemisphere.

For instance, from the slave access device 330, the master access device 110 may receive a first signal or stream corresponding to a first radio frequency signal received through the first antenna element AE ₁ followed by the first antenna feed 133, and a second signal or stream corresponding to a second radio frequency signal received through the second antenna element AE ₂ followed by the second antenna feed 134, e.g. by switching the first antenna element AE ₁ and the second antenna element AE ₂ alternatively via the first switch 132.

In addition, from the slave access device 330, the master access device 110 may receive a third signal or stream corresponding to a third radio frequency signal received through the third antenna element AE ₃ followed by the third antenna feed 333, and a fourth signal or stream corresponding to a fourth radio frequency signal received through the fourth antenna element AE ₄ followed by the fourth antenna feed 334, e.g. by switching the third antenna element AE ₃ and the fourth antenna element AE ₄ alternatively via the second switch 332.

The master access device 110, especially the CPU 111 of the master access device 110, may assess one or more signal parameters of the first signal or stream and/or of the second signal or stream, especially to identify which of the two polarizations corresponding to the first antenna element AE ₁ and the second antenna element AE ₂ is advantageous, and may accordingly toggle the first switch 132 to maintain communication only via the antenna element with the advantageous polarization.

Additionally or alternatively, if the first antenna element AE ₁ and the second antenna element AE ₂ both result in advantageous polarizations, the master access device 110 may switch the first antenna element AE ₁ and the second antenna element AE ₂ at a regular interval, e.g. by toggling the first switch 132 at a regular interval, to maintain communication via both the first antenna element AE ₁ and the second antenna element AE ₂.

Additionally, the master access device 110, especially the CPU 111 of the master access device 110, may assess one or more signal parameters of the third signal or stream and/or of the fourth signal or stream, especially to identify which of the two polarizations corresponding to the third antenna element AE ₃ and the fourth antenna element AE ₄ is advantageous, and may accordingly toggle the second switch 332 to maintain communication only via the antenna element with the advantageous polarization.

Additionally or alternatively, if the third antenna element AE ₃ and the fourth antenna element AE ₄ both result in advantageous polarizations, the master access device 110 may switch the third antenna element AE ₃ and the fourth antenna element AE ₄ at a regular interval, e.g. by toggling the second switch 332 at a regular interval, to maintain communication via both the third antenna element AE ₃ and the fourth antenna element AE ₄.

It is to be noted that the slave access device 330 may comprise more than two transceivers, i.e. may operate on more than two radio frequency streams, and their respective antenna feeding schemes to further antenna arrays, which can be analogously implemented in the exemplified manner.

In Fig. 4, a fourth exemplary embodiment of the slave access device 330 is illustrated. Particularly, at the top of Fig. 4, an exemplary PCB implementation of the slave access device 330 is shown along the xy-axis. The PCB implementation can be realized by stacking a first PCB 401 on top of a second PCB 402. The first PCB 401 may comprise the first antenna array 136 and the second antenna array 336, especially the first antenna element AE ₁, the second antenna element AE ₂, the third antenna element AE ₃, and the fourth antenna element AE ₄, each may be arranged to have orthogonal radiation polarization of 45 degrees.

The second PCB 402 may comprise the first switch 132, the first antenna feed 133, the second antenna feed 134 along with the first phase shifter 135, as well as the second switch 332, the third antenna feed 333, and the fourth antenna feed 334 along with the second phase shifter 335. For example, the first switch 132 and the second switch 332 may be realized as RF MEMS or stripline switches. The first antenna feed 133, the second antenna feed 134, the third antenna feed 333, and the fourth antenna feed 334 may be realized as stripline transmission lines.

In this regard, the first phase shifter 135 can be realized as a stripline phase shifter along with the stripline transmission line according to the second antenna feed 134, e.g. by having an additional transmission line section with a defined amount of phase length. Analogously, the second phase shifter 335 can be realized as a stripline phase shifter along with the stripline transmission line according to the fourth antenna feed 334, e.g. by having an additional transmission line section with a defined amount of phase length, equal to or different from the first phase shifter 135.

In this regard, the first antenna feed 133 may be coupled to the first antenna element AE ₁ of the first antenna array 136 via a first connector 403. Additionally, the second antenna feed 134 may be coupled to the second antenna element AE ₂ of the first antenna array 136 via a second connector 404. Furthermore, the third antenna feed 333 may be coupled to the third antenna element AE ₃ of the second antenna array 336 via a third connector 405. Moreover, the fourth antenna feed 334 may be coupled to the fourth antenna element AE ₄ of the second antenna array 336 via a fourth connector 406. The first connector 403, the second connector 404, the third connector 405, and the fourth connector 406 may be RF connectors, e.g. spring contacts.

Although not shown, the second PCB 402 may comprise the first transceiver 131 and the second transceiver 331, and further circuitry and/or elements, e.g. power harvesting circuitry, that may be required for proper operation of the slave access device 330.

It is to be noted that, some of the components of the second PCB 402, e.g. the first switch 132, the first antenna feed 133, the second antenna feed 134, the first phase shifter 135, the second switch 332, the third antenna feed 333, the fourth antenna feed 334, and/or the second phase shifter 335, may be arranged in the first PCB 401 along with the first antenna array 136 and the second antenna array 336.

At the bottom of Fig. 4, the PCB implementation of the slave access device 330 is shown along the xz-axis. The first antenna array 136 and the second antenna array 336 may be realized in the first PCB 401, which may have a thickness t ₄₀₁ of 2 mm, i.e. a base material thickness. The overall thickness t may therefore be limited to about 4.5 mm, especially depending on the type of the RF connectors employed in-between the first PCB 401 and the second PCB 402.

In Fig. 5, simulation results for normalized far-field directivities of the

slave access device

130, 230, 330 are shown in polar form. For instance, the plot 501 may correspond to the first antenna element AE ₁ and the plot 502 may correspond to the second antenna element AE ₂.

It can be seen that the predefined amount of passive phase shift, especially a phase shift of 100 degrees, between the first antenna element AE ₁ and the second antenna element AE ₂ may accordingly tilt the respective beams approximately to theta +30 degrees and -30 degrees. For instance, the plot 502 shows a main lobe magnitude of 8.27 dBi with a main lobe direction of 32 degrees, a side lobe level of -4.8 dB, and an angular width of 58.6 degrees at an operating frequency of 5.5 GHz.

Along Figs 6A-6D, four exemplary beam directions of the slave access device 330 are illustrated. Particularly, Figs. 6A-6D show four high-directive beams, i.e. four quarter-hemisphere beams, in four different and/or orthogonal directions, especially resulting from four switching combinations of the first switch 132 and the second switch 332.

For example, Fig. 6A shows a first high-directive beam or a first quarter-hemisphere beam corresponding to the first radio frequency stream RF ₁ radiated from the first antenna element AE ₁, especially by toggling the first switch 132 to connect the first radio frequency stream RF ₁ to the first antenna element AE ₁ through the first antenna feed 133. The directivity of the radiated beam is exemplarily illustrated with a white arrow along the top-left direction with a gain rating of 6.34 dBi.

In addition, Fig. 6B shows a second high-directive beam or a second quarter-hemisphere beam corresponding to the second radio frequency stream RF ₂ radiated from the third antenna element AE ₃, especially by toggling the second switch 332 to connect the second radio frequency stream RF ₂ to the third antenna element AE ₃ through the third antenna feed 333. The directivity of the radiated beam is exemplarily illustrated with a white arrow along the top-right direction with a gain rating of 6.27 dBi.

Furthermore, Fig. 6C shows a third high-directive beam or a third quarter-hemisphere beam corresponding to the second radio frequency stream RF ₂ radiated from the fourth antenna element AE ₄, especially by toggling the second switch 332 to connect the second radio frequency stream RF ₂ to the fourth antenna element AE ₄ through the fourth antenna feed 334. The directivity of the radiated beam is exemplarily illustrated with a white arrow along the bottom-left direction with a gain rating of 6.49 dBi.

Moreover, Fig. 6D shows a fourth high-directive beam or a fourth quarter-hemisphere beam corresponding to the first radio frequency stream RF ₁ radiated from the second antenna element AE ₂, especially by toggling the first switch 132 to connect the first radio frequency stream RF ₁ to the second antenna element AE ₂ through the second antenna feed 134. The directivity of the radiated beam is exemplarily illustrated with a white arrow along the bottom-right direction with a gain rating of 6.45 dBi.

In Fig. 7, simulation results of return loss and port isolations for the slave access device 330 are illustrated. In the plot, the x axis denotes the frequency in GHz and the y axis denotes the magnitude of scattering parameters in dB. Herein, the curve 701 represents the return loss corresponding to a radio frequency stream, e.g. corresponding to the second radio frequency stream RF ₂. It can be seen that, in the frequency band 5.2 GHz –5.8 GHz (especially suitable for wireless local area network standard IEEE 802.11. a/n/ac/ax) , more than -10 dB of return loss can be achieved, which may reassure a high antenna total efficiency.

Furthermore, the curve 702 represents port isolations between two radio frequency streams, e.g. port isolations between the first radio frequency stream RF ₁ and the second radio frequency stream RF ₂. It can be seen that, in the frequency band 5.2 GHz –5.8 GHz, more than 30 dB of port isolation can be achieved, which may reassure a high MIMO diversity.

In Fig. 8, a second exemplary embodiment of the indoor optical network 800 is illustrated. The indoor optical network may comprise a master access device or a Primary optical network terminal P-ONT and a number of N slave access devices or Edge optical network terminals E-ONT ₁-E-ONT _N. The master access device P-ONT may correspond to the master access device 110 of the indoor optical network 100, and each of the number of N slave access devices E-ONT ₁-E-ONT _N may correspond to the slave access devices 130 or the slave access device 230 or the slave access device 330. In this regard, the number of N slave access devices E-ONT ₁-E-ONT _N are optically coupled to the master access device P-ONT through an optical splitter (SPL) 801.

In this regard, the master access device P-ONT may be coupled to the optical splitter 801 via an input fiber optic link 120 of the optical splitter, and the optical splitter 801 may split the input over a number of N parallel fiber optic links 802 ₁-802 _N. Each of the number of N slave access devices E-ONT ₁-E-ONT _N may be coupled to the optical splitter 801 via the number of N parallel fiber optic links 802 ₁-802 _N, respectively.

The optical splitter 801 may be a passive optical splitter. For instance, the optical splitter 801 may be a PLC splitter, e.g. a 1xN PLC splitter, which may split an input, i.e. an incoming light signal, into a number of N parallel outputs. Alternatively, the optical splitter 801 may be a FBT splitter, e.g. a 1xN FBT splitter that may comprise a number of N welded or fused optical fibers.

In Fig. 9, an exemplary implementation of the indoor optical network 800 is illustrated for different indoor serving locations. In this example, a first slave access device 901, a second slave access device 902, and a third slave access device 903 are mounted at their respective locations, e.g. wall-mounted, and are coupled to the master access device 110 through the optical splitter 801. The first slave access device 901, the second slave access device 902, and the third slave access device 903 may correspond to any of the

slave access devices

130, 230, 330. For example, the first slave access device 901, the second slave access device 902, and the third slave access device 903 may correspond to the slave access device 330.

The first slave access device 901 is illustrated with its four exemplary quarter-hemisphere beams 901 ₁-901 ₄, the second slave access device 902 is illustrated with its four exemplary quarter-hemisphere beams 902 ₁-902 ₄, and the third slave access device 903 is illustrated with its four exemplary quarter-hemisphere beams 903 ₁-903 ₄. In this regard, the first quarter-

hemisphere beams

901 ₁, 902 ₁, and 903 ₁ may correspond to the quarter-hemisphere beam illustrated in Fig. 6A, the second quarter-

hemisphere beams

901 ₂, 902 ₂, and 903 ₂ may correspond to the quarter-hemisphere beam illustrated in Fig. 6B, the third quarter-

hemisphere beams

901 ₃, 902 ₃, and 903 ₃ may correspond to the quarter-hemisphere beam illustrated in Fig. 6C, and the fourth quarter-

hemisphere beams

901 ₄, 902 ₄, and 903 ₄ may correspond to the quarter-hemisphere beam illustrated in Fig. 6D.

In this example, it can be seen that the first quarter-hemisphere beam 901 ₁, the third quarter-hemisphere beam 901 ₃, and the fourth quarter-hemisphere beam 901 ₄, of the first slave access device 901 may not be advantageous due to the blockage caused by the wall and the furniture and the floor. As such, the master access device 110 may configure the first slave access device 901 to maintain its main communication in the direction of the second quarter-hemisphere beam 901 ₂, e.g. via antenna switching technique described before.

It can also be seen that, due to the positioning of the second slave access device 902, first quarter-hemisphere beam 902 ₁, the second quarter-hemisphere beam 902 ₂, the third quarter-hemisphere beam 902 ₃, and the fourth quarter-hemisphere beam 902 ₄ of the second slave access device 902 may be considered advantageous, i.e. no line-of-sight blockage. As such, the master access device 110 may configure the second slave access device 902 to maintain its communication in all directions according to its four quarter-hemisphere beams 902 ₁-902 ₄.

It can moreover be seen that the second quarter-hemisphere beam 903 ₂, and the fourth quarter-hemisphere beam 903 ₄, of the third slave access device 903 may not be advantageous due to its positioning in the vicinity of the window, e.g. noise source and/or EMI. As such, the master access device 110 may configure the third slave access device 903 to maintain its communication only in the directions of the first quarter-hemisphere beam 903 ₁, and the third quarter-hemisphere beam 903 ₃.

In Fig. 10, an exemplary embodiment of the method 1000 according to the third aspect of this disclosure is illustrated. In a first step 1001, one or more slave access devices are provided, whereby each slave access device comprises at least one transceiver and at least two antenna elements operably coupled to the at least one transceiver in a switchable manner. In a second step 1002, one or more parameters of a radiated or received radio frequency signal from each slave access device are assessed by a master access device. In a third step 1003, the at least two antenna elements of the slave access device are switched by the master access device based on the one or more parameters.

The conventional antenna systems of Edge ONTs deployed in a FTTR-2H network may consist of fixed-beam low and/or high gain antennas in order to allow high quality Wi-Fi services. For example, a conventional Edge ONT with 5 GHz Wi-Fi band may comprise compact antennas with omni-directional radiation patterns or a mix of onmi-directional and high-gain antennas. A high-gain antenna may generate a focused beam toward the center of each serving location without sufficient radiations to tangential angles. By contrast, a low-gain antenna with a quasi-omni-directional radiation pattern may reassure radiations to any possible angles, however with the disadvantage of high interferences between neighboring Edge ONTs. As an example, bulky EMI may be experienced by two Edge ONTs located on two sides of a thin wall while having strong backward radiations, e.g. from back-up omni-directional antennas.

The more complicated antenna systems, such as the phased array antennas, metasurface, or metavolume antennas may not be a feasible solution for an Edge ONT, especially in terms of cost and complexity, as it requires complex phase array feeding system and a large number of antenna elements.

This disclosure presents a smart antenna solution for the Edge ONTs to make performant radiation toward users in front hemisphere while maintaining a minimal-dependency on the installation locations of the Edge ONTs, especially by dividing the front hemisphere to few regions and to select some or all regions based on their usefulness, and to establish the channel only on such regions for each of the RF streams. This advantageously solves the limited coverage of fixed-beam antennas, as well as the dependency of their performance on installation locations.

It is important to note that, in the description as well as in the claims, the word “comprising” does not exclude other elements or steps and the indefinite article “a” or “an” does not exclude a plurality. A single element or other unit may fulfill the functions of several entities or items recited in the claims. Furthermore, the word “coupled” implies that the elements may be directly connected together or may be coupled through one or more intervening elements. Moreover, the disclosure with regard to any of the aspects is also relevant with regard to the other aspects of the disclosure.

Although the disclosure has been illustrated and described with respect to one or more implementations, equivalent alterations and modifications will occur to others skilled in the art upon the reading and understanding of this specification and the annexed drawings. In addition, while a particular feature of this disclosure may have been disclosed with respect to only one of several implementations, such feature may be combined with one or more other features of the other implementations as may be desired and advantageous for any given or particular application.

Claims

A master access device (110) for an indoor optical network (100, 800) ,

wherein the indoor optical network comprises one or more slave access devices (130, 230, 330) optically coupled to the master access device (110) ,

wherein each slave access device (130, 230, 330) comprises at least one transceiver (131) and at least two antenna elements (AE ₁, AE ₂) operably coupled to the at least one transceiver (131) in a switchable manner, and

wherein the master access device (110) is configured to assess one or more parameters of a radiated or received radio frequency, RF, signal from each slave access device (130, 230, 330) and to switch the at least two antenna elements (AE ₁, AE ₂) of the slave access device (130, 230, 330) based on the one or more parameters.
The master access device according to claim 1, wherein the one or more parameters of the radiated or received radio frequency, RF, signal comprise at least one of a radio transmit power, an effective isotropic radiated power, a received signal strength indicator, a signal to noise ratio, and a front to back ratio.
The master access device according to claim 1 or 2, wherein the master access device (110) is further configured to switch the at least two antenna elements (AE ₁, AE ₂) sequentially at a regular interval.
The master access device according to any of claims 1 to 3,

wherein each slave access device (130, 230, 330) comprises at least one further transceiver (331) and at least two further antenna elements (AE ₃, AE ₄) operably coupled to the at least one further transceiver (331) in a switchable manner, and

wherein the master access device (110) is configured to assess the one or more parameters of the radiated or received radio frequency, RF, signal from each slave access device (130, 230, 330) , and to switch the at least two antenna elements (AE ₁, AE ₂) and the at least two further antenna elements (AE ₃, AE ₄) of the slave access device (130, 230, 330) based on the one or more parameters.
The master access device according to claim 4, wherein:

the master access device (110) is configured to switch the at least two antenna elements (AE ₁, AE ₂) and the at least two further antenna elements (AE ₃, AE ₄) of each slave access device (130, 230, 330) simultaneously, or

the master access device (110) is configured to switch the at least two antenna elements (AE ₁, AE ₂) and the at least two further antenna elements (AE ₃, AE ₄) of each slave access device (130, 230, 330) sequentially at a regular interval.
An indoor optical network (100, 800) comprising:

the master access device (110) according to any of claims 1 to 5, and

the one or more slave access devices (130, 230, 330) optically coupled to the master access device (110) .
The indoor optical network according to claim 6,

wherein each slave access device (130, 230, 330) further comprises a phase shifter (135) coupled between one of the at least two antenna elements (AE ₁, AE ₂) and the at least one transceiver (131) .
The indoor optical network according to claim 7, wherein:

the phase shifter (135) is a passive phase shifter, and

the phase shifter (135) is configured to apply a phase shift by a predefined amount.
The indoor optical network according to one of the claims 6 to 8, wherein the at least two antenna elements (AE ₁, AE ₂) of each slave access device (130, 230, 330) are Microstrip antennas or patch antennas.
The indoor optical network according to any of claims 7 to 9, wherein:

each slave access device (130, 230, 330) comprises at least one further transceiver (331) and at least two further antenna elements (AE ₃, AE ₄) operably coupled to the at least one further transceiver (331) in a switchable manner, and

each slave access device (130, 230, 330) comprises a further phase shifter (335) coupled between one of the at least two further antenna elements (AE ₃, AE ₄) and the at least one further transceiver (331) .
The indoor optical network according to claim 10, wherein:

the at least two antenna elements (AE ₁, AE ₂) and the at least two further antenna elements (AE ₃, AE ₄) of each slave access device (130, 230, 330) are configured to radiate signal with polarizations orthogonal to each other,

each of the at least two antenna elements (AE ₁, AE ₂) and of the at least two further antenna elements (AE ₃, AE ₄) of each slave access device (130, 230, 330) are configured to radiate signal to cover a respective portion of front-hemisphere.
The indoor optical network according to claim 10 or 11, wherein:

the further phase shifter (335) is a passive phase shifter, and

the further phase shifter (335) is configured to apply a phase shift by a predefined amount, preferably equal to the phase shift applied by the phase shifter (135) .
The indoor optical network according to any of claims 7 to 12, wherein:

each slave access device (130, 230, 330) comprises a first printed circuit board layer (401) comprising the at least two antenna elements (AE ₁, AE ₂) and/or the at least two further antenna elements (AE ₃, AE ₄) , and a second printed circuit board layer (402) comprising the at least one transceiver (131) and the phase shifter (135) , and/or the at least one further transceiver (331) and the further phase shifter (335) , and

the first printed circuit board layer (401) is assembled on top of the second printed circuit board layer (402) via one or more connectors (403, 404, 405, 406) .
The indoor optical network according to any of claims 6 to 12, wherein the at least one of the slave access devices (130, 230, 330) has a package dimension of around 86 mm x 86 mm.
The indoor optical network according to any of claims 6 to 14, wherein:

the indoor optical network (100, 800) comprises two or more slave access devices (130, 230, 330) , and

at least two of the slave access devices (130, 230, 330) are optically coupled to the master access device (110) via an optical splitter (801) .
A method (1000) for operating one or more slave access devices (130, 230, 330) of an indoor optical network (100, 800) , each slave access device comprising at least one transceiver (131) and at least two antenna elements (AE ₁, AE ₂) operably coupled to the at least one transceiver (131) in a switchable manner, wherein the method comprises:

assessing (1002) one or more parameters of a radiated or received radio frequency, RF, signal from each slave access device (130, 230, 330) by a master access device (110) , and

switching (1003) the at least two antenna elements (AE ₁, AE ₂) of the slave access device (130, 230, 330) based on the one or more parameters by the master access device (110) .
A computer program comprising instructions which, when the program is executed by a processor of the master access device (110) , cause the processor to perform the method (1000) according to claim 16.