Network devices for indoor networks

Abstract

This disclosure relates to network devices for indoor optical networks. A master access device of this disclosure is provided for an indoor optical network, which comprises one or more slave access devices optically coupled to the master access device. The master access device comprises one or more optical amplifiers, each being configured to amplify a downstream optical signal or amplify an upstream optical signal; and an optical splitter / combiner module, configured to split the amplified downstream optical signal into one or more split optical signals, and send the one or more split optical signals to the one or more slave access devices, and / or combine one or more upstream optical signals from the one or more slave access devices into a combined upstream optical signal, wherein the combined upstream optical signal is a to- be-amplified upstream optical signal. An optical communication system is further provided in this disclosure.

Description

[0001] NETWORK DEVICES FOR INDOOR NETWORKS

[0002] TECHNICAL FIELD

[0003] The present disclosure relates to network devices for indoor networks, especially for indoor optical networks. In particular, this disclosure proposes a master access devices, an optical communication system, and corresponding methods.

[0004] BACKGROUND

[0005] Fiber to the Room (FTTR), also known as Fibre In-premises networking, is an emerging and rapidly growing application as an in-home network to deliver higher quality networking experience, for example by distributing and coordinating WiFi routers.

[0006] The connection between the outside access network and the in-home FTTR network is known as the Main FTTR Unit (MFU) or also as the FTTR Gateway. The outside access network that serves FTTR systems in the vast majority of cases a fiber-to-the-home (FTTH) solution employing standardized Passive Optical Network (PON) systems such as Gigabit Passive Optical Network (G-PON) or 10 Gigabit Symmetrical Passive Optical Network (XGS-PON). The MFU is today an element where the XGS-PON or G-PON access network is terminated with an optical network terminal (ONT) and the FTTR in-home network starts. ONTs are sometimes referred to as optical networking units (ONUs) in PON terminology.

[0007] Differently from today’s in-home network that relies mostly on WiFi or copper-based network solutions, for FTTR there is a trend where the in-home network is managed by the same network operator as the access network. The network operator hence deploys and manages the MFU, which includes software control for remote management.

[0008] A conventional MFU consists of complex elements. The MFU consists of one ONT transceiver, one FTTR optical line termination (OLT) transceiver, and traffic routing functionality towards the sub-FTTR units (SFU). The OLT inside the MFU is sometimes referred to as the main FTTR transceiver. In the MFU, the optical signal of the PON is converted back to the electrical domain by the ONT, and the traffic meant for the FTTR network is separated from the traffic of other users. The selected traffic is then passed to the OLT of the FTTR system. This can be inefficient considering the power consumption since the traffic is mostly traversing the FTTR gateway, but still, it needs to be optical-electro-optical (OEO) converted and electrically processed. In addition, the OLT is a more expensive element in terms of cost compared to an ONT by a factor of 4 to 5. The OLT can be complex to manage as the data needs to be re-encapsulated, which requires remote provisioning from the network operator.

[0009] Therefore, a simple and efficient solution for the network operator to manage both the PON and FTTR, is desired.

[0010] SUMMARY

[0011] In view of the above-mentioned challenges and disadvantages, this disclosure aims to provide an improved master access devices, an improved indoor optical network, and corresponding methods for an indoor optical network. An objective is to simplify the management of the network and allow simpler WiFi AP coordination. Another objective is to simplify the traffic routing in the master access devices to reduce the power consumption and preferably also the cost. Another objective is to provide a solution that can support simultaneously different optical systems.

[0012] 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.

[0013] 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. The master access device comprises one or more optical amplifiers, each being configured to: amplify a downstream optical signal, or amplify an upstream optical signal. The master access device further comprises an optical splitter / combiner module, which is configured to split the amplified downstream optical signal into one or more split optical signals, and send the one or more split optical signals to the one or more slave access devices, and / or combine one or more upstream optical signals from the one or more slave access devices into a combined upstream optical signal, wherein the combined upstream optical signal is a to-be-amplified upstream optical signal. This disclosure proposes to use optical amplifier(s) (OAs) in the MFU to create a transparent optical path between the outside access network and the in-home FTTR network. As only OAs and passive optical components (e.g., optical splitter) are used in the MFU, this effectively creates a direct all-optical path from the network operator OLT in the Central Office to the WiFi Access Point in the Home network, where no OEO or active traffic routing is present. The network operators could then directly manage all the WiFi APs of the FTTR networks that are connected to the same access network.

[0014] In an implementation form of the first aspect, the one or more optical amplifiers comprise a first downstream optical amplifier, which is configured to amplify a first downstream optical signal from a first passive optical network.

[0015] Different OA technologies can be used to implement the OA used in the proposed MFU. For example, semiconductor optical amplifiers (SOAs) can be used to amplify the four bands required to transmit G-PON and XGS-PON: 1260-1280nm 1290-1330nm, 1480-1500nm, and 1575-1579nm. Doped Fiber or Doped Waveguide amplifiers can also be used to amplify in the C-band (with Erbium doping) or in the O-band (with Praseodymium doping).

[0016] In an implementation form of the first aspect, the one or more optical amplifiers further comprise a second downstream optical amplifier, which is configured to amplify a second downstream optical signal from a second passive optical network, wherein the second passive optical network is different from the first passive optical network.

[0017] More than one downstream OA may be implemented in the MFU for amplifying more than one optical signal in the downstream direction.

[0018] In an implementation form of the first aspect, the master access device further comprises: a first multiplexer / demultiplexer (Mux / Demux) module, configured to separate a received optical stream into the first downstream optical signal and the second downstream optical signal; and a second Mux / Demux module, configured to combine the amplified first downstream optical signal and the amplified second downstream optical signal into an amplified optical stream. One optical multiplexer may be used to separate and combine the two downstream signals. Another optical multiplexer may be used to recombine the two downstream signals before entering the optical splitter.

[0019] In an implementation form of the first aspect, the one or more optical amplifiers further comprise a first upstream optical amplifier, which is configured to amplify a first upstream optical signal.

[0020] In an implementation form of the first aspect, the one or more optical amplifiers further comprise a second upstream optical amplifier, which is configured to amplify a second upstream optical signal. More than one upstream OA may be implemented in the MFU for amplifying more than one optical signal in the upstream direction.

[0021] In an implementation form of the first aspect, the first Mux / Demux module is further configured to combine the amplified first upstream optical signal and the amplified second upstream optical signal into an amplified upstream optical stream, and output the amplified upstream optical stream to the first passive optical network and / or the second passive optical network. The first Mux / Demux module may be used to separate and combine the two downstream signals and the two upstream signals.

[0022] In an implementation form of the first aspect, the master access device further comprises a first control module, which is configured to control whether to turn on or turn off the first upstream optical amplifier, and / or the second upstream optical amplifier.

[0023] In an implementation form of the first aspect, the first control module is further configured to turn on the first upstream optical amplifier and / or the second upstream optical amplifier only when any of the one or more slave access devices is transmitting to the master access device. A fast OA bias control can be used to turn on the OA(s) in the upstream direction only when one of the ONUs in the home network is transmitting to avoid noise accumulation.

[0024] In an implementation form of the first aspect, the second Mux / Demux module is further configured to separate the combined upstream optical signal into the first upstream optical signal and the second upstream optical signal. In an implementation form of the first aspect, the master access device further comprises a second control module, which is configured to control a gain for each of the one or more optical amplifiers. A management and control unit in the MFU may control the gains of the OAs.

[0025] In an implementation form of the first aspect, the second control module is further configured to control the gain for each of the one or more optical amplifiers based on a loss of the optical splitter / combiner module. The gain of the OA needs to be higher than the loss of the splitter in the FTTR network to compensate for the power and sensitivity loss, but not too high to avoid the Rx overload. Gain control of the SOA can be easily implemented by measuring the power before or after the FTTR splitter.

[0026] In an implementation form of the first aspect, the optical splitter / combiner module is further configured to provide a split optical signal to the second control module.

[0027] In an implementation form of the first aspect, the second control module is further configured to provide transmitting timing information of the one or more slave access devices to the first control module. The management and control unit in the MFU may also provide the timing information in the upstream direction to the fast OA bias control.

[0028] In an implementation form of the first aspect, the first control module is further configured to turn on or turn off the first upstream optical amplifier and / or the second upstream optical amplifier based on the transmitting timing information received from the second control module.

[0029] In some implementations, because the FTTR network is short (max 200m), the ONUs in the same home network are all at the same distance and the timing of the turn on / off is simplified. It is thus possible to know the exact timing required for turning on / off the SOAs by using an ONU in the MFU to listen to the transmission grants allowed to the AP-ONU and control accurately the turn on and off the SOAs.

[0030] In an implementation form of the first aspect, the master access device further comprises an optical detector, which is configured to detect whether there is an upstream optical signal from the one or more slave access devices. Alternatively, the fast SOA bias control may use a photodiode (PD) to detect the upstream signals coming from the ONUs of the home network. For instance, one of the unused splitter ports can be connected to a photodetector that is connected to the fast SO A bias control.

[0031] In an implementation form of the first aspect, the optical detector is further configured to provide a detection result to the first control module, and the first control module is further configured to turn on or turn off the first upstream optical amplifier and / or the second upstream optical amplifier based on the detection result.

[0032] According to a second aspect of this disclosure, an optical communication system is provided. The optical communication system comprises one or more PONs, and one or more indoor optical networks. Each indoor optical network comprises a master access device according to the first aspect or any one of the implementation forms of the first aspect, and comprises one or more slave access devices optically coupled to the master access device.

[0033] Implementation forms of the optical communication system of the second aspect may correspond to the implementation forms of the master access device of the first aspect described above. The method of the second aspect and its implementation forms achieve the same advantages and effects as described above for the master access device of the first aspect and its implementation forms.

[0034] According to a third aspect of this disclosure, a method is provided for operating a master access device for an indoor optical network. The indoor optical network comprises one or more slave access devices optically coupled to the master access device. The method comprises the steps of amplifying a downstream optical signal and / or amplifying an upstream optical signal; and splitting the amplified downstream optical signal into one or more split optical signals, and sending the one or more split optical signals to the one or more slave access devices; and / or combining one or more upstream optical signals from the one or more slave access devices into a combined upstream optical signal, wherein the combined upstream optical signal is a to-be- amplified upstream optical signal.

[0035] Implementation forms of the method of the third aspect may correspond to the implementation forms of the master access device of the first aspect described above. The method of the fourth aspect and its implementation forms achieve the same advantages and effects as described above for the master access device of the first aspect and its implementation forms. 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 a 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.

[0036] All devices, elements, units, and means described in the present application could be implemented in software or hardware elements or any kind of combination thereof. All steps that are performed by the various entities described in the present application as well as the functionalities described to be performed by the various entities are intended to mean that the respective entity is adapted to or configured to perform the respective steps and functionalities. Even if, in the following description of specific embodiments, a specific functionality or step to be performed by external entities is not reflected in the description of a specific detailed element of that entity that performs that specific step or functionality, it should be clear for a skilled person that these methods and functionalities can be implemented in respective software or hardware elements or any kind of combination thereof.

[0037] BRIEF DESCRIPTION OF THE DRAWINGS

[0038] 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:

[0039] FIG. 1 shows a master access device according to an embodiment of the disclosure;

[0040] FIG. 2 shows an optical communication system according to an embodiment of the disclosure;

[0041] FIG. 3 shows a master access device according to an embodiment of the disclosure;

[0042] FIG. 4 shows a master access device according to an embodiment of the disclosure;

[0043] FIG. 5 shows an optical communication system according to an embodiment of the disclosure;

[0044] FIG. 6 shows an optical communication system according to an embodiment of the disclosure; FIG. 7 shows an optical communication system according to an embodiment of the disclosure; and

[0045] FIG. 8 shows an exemplary flow diagram of the method according to an embodiment of this disclosure.

[0046] DETAILED DESCRIPTION OF EMBODIMENTS

[0047] Illustrative embodiments of a master access device, an optical communication system, and a corresponding method for operating a master access device for an indoor optical network are described with reference to the figures. Although this description provides a detailed example of possible implementations, the details are intended to be exemplary and in no way limit the scope of the application.

[0048] Moreover, an embodiment / example may refer to other embodiments / examples. For example, any description including but not limited to terminology, element, process, explanation, and / or technical advantage mentioned in one embodiment / example is applicative to the other embodiments / examples.

[0049] FIG. 1 shows a master access device 100 for an indoor optical network 10 according to an embodiment of the disclosure.

[0050] The master access device 100 may comprise processing circuitry (not shown) configured to perform, conduct, or initiate the various operations of the master access device 100 described herein. The processing circuitry may comprise hardware and software. The hardware may comprise analog circuitry, digital circuitry, or both analog and digital circuitry. The digital circuitry may comprise components such as application-specific integrated circuits (ASICs), field-programmable arrays (FPGAs), digital signal processors (DSPs), or multi-purpose processors. The master access device 100 may further comprise memory circuitry, which stores one or more instruction(s) that can be executed by the processor or by the processing circuitry, in particular under the control of the software. For instance, the memory circuitry may comprise a non-transitory storage medium storing executable software code which, when executed by the processor or the processing circuitry, causes the various operations of the master access device 100 to be performed. In one embodiment, the processing circuitry comprises one or more processors and a non-transitory memory connected to the one or more processors. The non- transitory memory may carry executable program code which, when executed by the one or more processors, causes the master access device 100 to perform, conduct, or initiate the operations or methods described herein.

[0051] The indoor optical network 10 comprises one or more slave access devices 200, 200’ optically coupled to the master access device 100. Although only two slave access devices 200, 200’ are shown in FIG. 1, the indoor optical network 10 proposed in this disclosure may comprise further slave access devices. In some implementations all slave access devices are identical or parallel.

[0052] The master access device 100 comprises one or more optical amplifiers 101, each being configured to amplify a downstream optical signal, or amplify an upstream optical signal. The one optical amplifier block 101 shown in this figure merely represents an example, it does not limit the actual number of the optical amplifiers in this embodiment. The master access device 100 further comprises an optical splitter / combiner module 102, which is configured to split the amplified downstream optical signal into one or more split optical signals, and / or combine one or more upstream optical signals from the one or more slave access devices 200, 200’ into a combined upstream optical signal. The combined upstream optical signal is a to-be-amplified upstream optical signal, e.g., the combined upstream optical signal is to be amplified by the one or more optical amplifiers 101.

[0053] The master access device 100, or the optical splitter / combiner module 102 of the master access device 100 may be further configured to send the one or more split optical signals to the one or more slave access devices 200, 200’. In some implementations the master access device 100, or the optical splitter / combiner module 102 of the master access device 100 may comprise means (such as a transmitter, or a transmitting module) for sending optical signals. Similarly, the master access device 100, or the optical splitter / combiner module 102 of the master access device 100 may comprise means (such as a receiver, or a receiving module) for receiving the one or more upstream optical signals from the one or more slave access devices 200, 200’.

[0054] This disclosure proposes a master access device, e.g., an MFU or an optically transparent MFU, for passive networks. The disclosure proposes to use OA in the MFU to create a transparent optical path between the outside access network and the in-home FTTR network. This effectively creates a direct all-optical path from the OLT from the network operator (in the central office) to the WiFi Access Point (AP) in the home network, where no OEO conversion or active traffic routing is present (as shown in FIG. 2). The network operators could then directly manage all the WiFi access point of the FTTR networks that are connected to the same access network.

[0055] FIG. 2 shows an all-optical connection between PON(s) and the FTTR home network using the optically transparent MFU, according to an embodiment of this disclosure. The MFU of FIG. 2 may be the master access device 100 as shown in FIG. 1. It can be seen that only optical amplifiers (i.e., one or more optical amplifiers 101) and passive optical component (e.g., the splitter / combiner module 102) are used in the MFU. There is no OEO conversion in the MFU, which also means no OLT is used. Therefore, a simple ONU (not shown) may be used to manage and control the functionalities of the MFU.

[0056] In this disclosure, different OA technologies can be used in the proposed MFU. For example, SOAs can be used to amplify the four bands required to transmit G-PON and XGS-PON: 1260- 1280nm 1290-1330nm, 1480-1500nm, and 1575-1579nm. Doped Fiber or Doped Waveguide amplifiers can also be used to amplify in the C-band (with Erbium doping) or in the O-band (with Praseodymium doping).

[0057] This disclosure is directly applicable to the PON network and to the FTTR home network that would be connected to it. In some implementations a direct extension of the PON network in the home network is created, as shown in FIG. 2. The PON OLT would be in the network operator's central office. The PON network can be based on G-PON or XGS-PON or a coexistence of both. The ODN fiber plant would connect the OLTs to the optically transparent MFU, e.g., the master access device 100. The MFU would then distribute over fiber the PON signal to the SFUs, e.g., the one or more slave access devices 200, 200’ that can contain an ONU and WiFi AP. The ONUs of the SFUs can be either G-PON or XGS-PON ONUs.

[0058] FIG. 3 shows an example schematic of a master access device 100 according to this disclosure. This optically transparent MFU may be for G-PON or XGS-PON. In one implementation, when the PON is a G-PON, only G-PON signals are amplified and transmitted through the MFU using SOAs as optical amplifiers. In another implementation, when the PON is an XGS-PON, only XGS-PON signals are amplified and transmitted through the MFU using SOAs as optical amplifiers. Optionally, the one or more optical amplifiers 101 comprise a first downstream optical amplifier 1011 configured to amplify a first downstream optical signal from a first PON. Optionally, the first PON may be either G-PON or XGS-PON.

[0059] Optionally, the one or more optical amplifiers 101 further comprise a first upstream optical amplifier 1013 configured to amplify a first upstream optical signal.

[0060] The first downstream optical amplifier 1011 and / or the first upstream optical amplifier 1013 may be SOAs. The SOAs have different amplification bands optimized for each of the upstream optical signal and downstream optical signal. The first downstream optical amplifier 1011 and / or the first upstream optical amplifier 1013 may also be implemented using another type of optical amplifier.

[0061] The optical splitter provides the fiber connections that are routed to the SFUs, e.g., the one or more slave access devices 200, 200’. One of the outputs of the optical splitter / combiner module 102 is connected to an ONU, which could be a G-PON or an XGS-PON ONU. In one implementation, if the ONU of the master access device 100 is a G-PON ONU, the first downstream optical signal may be at 1490nm, and the first upstream optical signal may be at 1310nm. In another implementation, if the ONU of the master access device 100 is an XGS- PON ONU, the first downstream optical signal may be at 1577nm, and the first upstream optical signal may be at 1270nm. The first downstream optical amplifier 1011 and the first upstream optical amplifier 1013 are configured to work at the corresponding amplification bands optimized for each of the optical signals, respectively.

[0062] The ONU inside the MFU can be used to provide the data connectivity for an AP inside the MFU and also to provide the connection to a management and control unit of the MFU and the AP. The management and control unit also receives information from the management system of the PON.

[0063] The management and control unit in the MFU may control the gains of the OAs, and optionally in the upstream direction also provide the timing information to a fast OA bias control. The fast OA bias control can be used to turn on the OA(s) in the upstream direction only when one of the ONUs in the home network is transmitting to avoid noise accumulation. That is, according to an embodiment of this disclosure, the master access device 100 further comprises a first control module 105, e.g., the fast OA bias control, which is configured to control whether to turn on or turn off the first upstream optical amplifier 1013.

[0064] The master access device 100 further comprises a second control module 106, e.g., the management and control unit of the MFU, which is configured to control a gain for each of the one or more optical amplifiers 101. The second control module 106 may be considered as also comprising the ONU of the MFU.

[0065] In particular, the optical splitter / combiner module 102 is further configured to provide a split optical signal to the second control module 106, e.g., to the ONU.

[0066] Optionally, the second control module 106 may be further configured to control the gain for each of the one or more optical amplifiers 101 based on a loss of the optical splitter / combiner module 102.

[0067] Optionally, the second control module 106 may be further configured to provide transmitting timing information of the one or more slave access devices 200, 200’ to the first control module 105.

[0068] Accordingly, the first control module 105 is further configured to turn on or turn off the first upstream optical amplifier 1013 based on the transmitting timing information received from the second control module 106.

[0069] Optionally, the master access device 100 may further comprise an optical detector 107. The optical detector 107 is configured to detect whether there is an upstream optical signal from the one or more slave access devices 200, 200’.

[0070] According to an embodiment of this disclosure, the optical detector 107 is further configured to provide a detection result to the first control module 105. Optionally, the first control module 105 is further configured to turn on or turn off the first upstream optical amplifier 1013 based on the detection result. Further OAs may be implemented in the MFU for amplifying more than one optical signal in two directions (i.e., upstream direction and downstream direction).

[0071] FIG. 4 shows another example schematic of a master access device 100, according to this disclosure. In this example, there are two downstream signals and two upstream signals, which are at four different wavelengths. The master access device 100 of FIG. 4 may be based on the master access device 100 of FIG. 3.

[0072] This schematic implements the optically transparent MFU for both G-PON and XGS-PON. Four separate SOAs are used here to amplify the optical signals in the two directions. The SOAs have different amplification bands optimized for each of the four signals.

[0073] In this embodiment, the one or more optical amplifiers 101 further comprise a second downstream optical amplifier 1012, configured to amplify a second downstream optical signal from a second PON, wherein the second PON is different from the first PON, from which the first downstream optical signal comes.

[0074] In addition, the one or more optical amplifiers 101 further comprise a second upstream optical amplifier 1014, configured to amplify a second upstream optical signal.

[0075] One optical multiplexer may be used to separate and combine the two downstream signals and the two upstream signals. Another optical multiplexer may be used to recombine the four signals before entering the optical splitter, e.g., the optical splitter / combiner module 102, which provides the fiber connections that are routed to the SFUs, the one or more slave access devices 200, 200’.

[0076] According to an embodiment of this disclosure, the master access device further comprises a first Mux / Demux module 103 configured to separate a received optical stream into the first downstream optical signal and the second downstream optical signal, and a second Mux / Demux module 104 configured to combine the amplified first downstream optical signal and the amplified second downstream optical signal into an amplified optical stream.

[0077] Possibly, the first Mux / Demux module 103 is further configured to combine the amplified first upstream optical signal and the amplified second upstream optical signal into an amplified upstream optical stream, and output the amplified upstream optical stream to the first PON and / or the second PON.

[0078] Optical amplifiers (e.g., 1011, 1012, 1013, and 1014) shown in FIG. 4 may be implemented using SOAs. However, other types of optical amplifiers may also be used in the proposed MFU. For example, the XGS-PON downstream at 1577nm can utilize an Erbium Doped Fiber Amplifier (EDFA) or an Erbium Doped Waveguide Amplifier (EDWA). In the upstream bands around 1270nm and 1300nm Praseodymium Doped Fiber Amplifier (PDF A) could be used. In this example, the first downstream optical amplifier 1011 can be implemented using an EDFA or EDWA, and the first upstream optical amplifier 1013 and the second upstream optical amplifier 1014 can be implemented using PDF As. The rest of the MFU has the same structure as shown in FIG. 4.

[0079] One of the outputs of the optical splitter / combiner module 102 is connected to an ONU, which could be a G-PON or an XGS-PON ONU. The ONU inside the MFU can be used to provide the data connectivity for an AP inside the MFU and also to provide the connection to a management and control unit of the MFU.

[0080] According to an embodiment of this disclosure, the first control module 105 is further configured to control whether to turn on or turn off the second upstream optical amplifier 1014.

[0081] Optionally, the first control module 105 is further configured to turn on the first upstream optical amplifier 1013 and / or the second upstream optical amplifier 1014 only when any of the one or more slave access devices 200, 200’ is transmitting to the master access device 100.

[0082] In particular, the first control module 105 may be configured to turn on or turn off the first upstream optical amplifier 1013 and / or the second upstream optical amplifier 1014 based on the transmitting timing information received from the second control module 106.

[0083] As discussed in the previous embodiment, the master access device 100 may further comprise an optical detector 107, which detects whether there is an upstream optical signal from the one or more slave access devices 200, 200’ and provides a detection result to the first control module 105. Optionally, the first control module 105 is further configured to turn on or turn off the first upstream optical amplifier 1013 and / or the second upstream optical amplifier 1014 based on the detection result.

[0084] In this embodiment, the second Mux / Demux module 104 is further configured to separate the combined upstream optical signal, e.g., the one from the optical splitter / combiner module 102, into the first upstream optical signal and the second upstream optical signal.

[0085] FIG. 5 shows an optical communication system 1 comprising one or more PONs, and one or more indoor optical networks 10, wherein each indoor optical network 10 comprises a master access device 100 as shown in one of the FIG. 1 to FIG. 4, and comprises one or more slave access devices 200, 200’ optically coupled to the master access device 100.

[0086] According to embodiments of this disclosure, the use of OAs in the MFU can increase the link budget for G-PON and XGS-PON systems to support an extra optical splitter in the MFU which is today maximum a x8 factor. OAs have been shown to provide advantages in the trunk part of the ODN before the splitters, but never as mid-point extenders as proposed in this disclosure.

[0087] FIG. 6 shows an example of the split ratio enabled by the proposed MFU in the PON ODN and the FTTR. In some implementations an MFU with OAs can support the maximum link budget of class E2 of the XGS-PON standard, which usually corresponds to a split ratio of 1x64 in the ODN. The overall split of the new PON+FTTR network is increased to 64x8=512 endpoints, which can be either populated with G-PON or XGS-PON ONUs.

[0088] For instance, in one implemention example for downstream XGS-PON for E2 class, data rate is lOGb / s NRZ (9.95328Gb / s), Extinction Ratio (ER) of the transmitter is 8.2dB, the minimum receiver sensitivity -28dBm (using an APD). On the FTTR network side, the maximum insertion loss (IL) of 18dB and length of 200 m is considered. Inside the optically transparent MFU, an OA with gain of 20dB and noise figure of 8dB (worst case for an SOA) and a Rx optical filter of 20nm, are used. It may be undersood that the Bit error rate (BER) at the SFU receiver as a function of the power at the input of the MFU improves when the transparent MFU is used. This means that extension of the PON to the FTTR network can be achieved using standard PON ONUs. Following the present disclosure, the standardized ONUs can still be used in the WiFi APs. In downstream, the ONU Rx contains a 20nm optical filter which limits the OA amplified spontaneous emission noise (ASE). The gain of the OA needs to be between OdB and 2dB higher than the loss of the splitter and of the fiber connection in the FTTR network to compensate for the power and sensitivity loss, but less than 4dB to avoid the Rx overload. As discussed in the previous embodiment, gain control of the OAs can be easily implemented by measuring the power before or after the FTTR splitter, e.g., the optical splitter / combiner module 102.

[0089] Another important point to be addressed is the noise addition (or funneling) generated by OAs in upstream. The ASE from the OAs adds at the optical splitters and for this reason, they are mid-stage ODN amplification or amplified splitters are not commonly used. The solution proposed in this disclosure uses SOAs that can be turned on / off quickly to avoid noise when the FTTR ONUs are not transmitting.

[0090] In some implementations the ASE noise created by the OAs of the MFUs, even when they are not transmitting, would add at the ODN optical splitter in upstream and reduce the Optical Signal to Noise Ratio (OSNR) at the OLT. For example, for 32 split the OSNR degradation is 15 dB, and for 64 split the OSNR degradation is 18 dB. To avoid the OSNR penalty at the OLT Rx the OAs can be gated only when the MFU is transmitting a signal in upstream.

[0091] FIG. 7 shows a gating of the OA gain when the SFUs connected to it are not transmitting to suppress the noise accumulation. In this way, the OSNR penalty from a single OA is minimal considering the power and loss values in the standards for PON and FTTR.

[0092] Because the FTTR network is short (e.g., max 200m), the ONUs in the same home network are all at the same distance and the timing of the turn on / off is simplified. It is possible to know the exact timing required for turning on / off the OAs by using an ONU in the MFU to listen to the transmission grants allowed to the AP-ONU and control accurately the turn on and off the OAs. Alternatively, one of the unused splitter ports can be connected to an optical detector (e.g., the optical detector 107 as shown in FIG. 3 or FIG. 4), such as a photodetector, which is connected to a fast feed-forward bias control of the OA (e.g., the first control module 105 as shown in FIG. 3 or FIG. 4). FIG. 8 shows a method 800 according to the third aspect of this disclosure, particularly operating a master access device 100 for an indoor optical network 10. In particular, the indoor optical network 100 comprises one or more slave access devices 200, 200’ optically coupled to the master access device 100. In a particular embodiment, the method 800 is performed by a master access device 100 shown in one of FIG. 1 to FIG. 5. The method 800 comprises a step 801 of amplifying a downstream optical signal and / or amplifying an upstream optical signal. The method 800 further comprises a step 802 of splitting the amplified downstream optical signal into one or more split optical signals, and a step 803 of sending the one or more split optical signals to the one or more slave access devices 200, 200’. The method 800 may further comprise a step 804 of combining one or more upstream optical signals from the one or more slave access devices 200, 200’ into a combined upstream optical signal, wherein the combined upstream optical signal is a to-be-amplified upstream optical signal.

[0093] Optionally, the master access device 100 may determine the loss of the splitter and of the fiber connection. Possibly, the method 800 may further comprise a step 805 of controlling the gain of the downstream optical signal such that it is between OdB and 2dB higher than the loss of the splitter and of the fiber connection. The method 800 may further comprise a step 806 of turning on quickly the gain in the upstream direction when an optical signal from a slave access device is present, or turning it off otherwise to avoid noise accumulation.

[0094] To summarize, embodiments of this disclosure propose an MFU or optically transparent MFU at the edge boundary between the PON access network and the FTTR home network. The optical signals are linked directly to the OLT in the central office and the ONUs of the SFUs, thereby simplifying the management of the network and allowing simpler WiFi AP coordination.

[0095] Embodiments of this disclosure propose to use OAs for providing amplification of the optical links in the MFU and an optical splitter is used to route the signals to the SFUs. In this way, the MFU is not performing OEO conversion and also is not performing traffic routing in the electrical domain, which reduces the power consumption. This also simplifies the MFU removing the need for an expensive OLT transceiver.

[0096] Further, the OAs in the MFU can be based on different technologies that cover different transmission bands with different advantages and disadvantages, for example, SOAs, Erbium or Praseodymium based Doped Fiber, or Doped Waveguide. All the different generations of PON systems can be supported by this idea by using the most appropriate OA for the specific wavelength. For example, the MFU can amplify and support simultaneously G-PON and XGS- PON systems.

[0097] OAs in upstream can be gated (SOAs can be easily gated in upstream) so that they are turned on only when the upstream signals from the home network are transmitted. This limits the noise accumulation that would otherwise not allow the network to function. An ONU in the MFU is used to detect the grant transmission signals for the ONUs in the home network.

[0098] The present disclosure has been described in conjunction with various embodiments as examples as well as implementations. However, other variations can be understood and effected by those persons skilled in the art and practicing the claimed embodiments of the disclosure, from the studies of the drawings, this disclosure, and the independent claims. In the claims as well as in the description 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. The mere fact that certain measures are recited in the mutually different dependent claims does not indicate that a combination of these measures cannot be used in an advantageous implementation. 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.

[0099] 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.

[0100] Furthermore, any method according to embodiments of the disclosure may be implemented in a computer program, having code means, which when run by processing means causes the processing means to execute the steps of the method. The computer program is included in a computer-readable medium of a computer program product. The computer-readable medium may comprise essentially any memory, such as a ROM (Read-Only Memory), a PROM (Programmable Read-Only Memory), an EPROM (Erasable PROM), a Flash memory, an EEPROM (Electrically Erasable PROM), or a hard disk drive.

[0101] Moreover, it is realized by the skilled person that embodiments of the master access device 100, or the optical communication system 1, comprises the necessary communication capabilities in the form of e.g., functions, means, units, elements, etc., for performing the solution. Examples of other such means, units, elements, and functions are processors, memory, buffers, control logic, encoders, decoders, rate matchers, de-rate matchers, mapping units, multipliers, decision units, selecting units, switches, interleavers, de-interleavers, modulators, demodulators, inputs, outputs, antennas, amplifiers, receiver units, transmitter units, DSPs, trellis-coded modulation (TCM) encoder, TCM decoder, power supply units, power feeders, communication interfaces, communication protocols, etc. which are suitably arranged together for performing the solution.

[0102] Especially, the processor(s) of the master access device 100 may comprise, e.g., one or more instances of a Central Processing Unit (CPU), a processing unit, a processing circuit, a processor, an Application Specific Integrated Circuit (ASIC), a microprocessor, or other processing logic that may interpret and execute instructions. The expression “processor” may thus represent a processing circuitry comprising a plurality of processing circuits, such as, e.g., any, some, or all of the ones mentioned above. The processing circuitry may further perform data processing functions for inputting, outputting, and processing of data comprising data buffering and device control functions, such as call processing control, user interface control, or the like.

Claims

CLAIMS1. A master access device (100) for an indoor optical network, wherein the indoor optical network comprises one or more slave access devices (200, 200’) optically coupled to the master access device (100), and wherein the master access device (100) comprises: one or more optical amplifiers (101), each being configured to: amplify a downstream optical signal, or amplify an upstream optical signal; and an optical splitter / combiner module (102), configured to: split the amplified downstream optical signal into one or more split optical signals, and send the one or more split optical signals to the one or more slave access devices (200, 200’), and / or combine one or more upstream optical signals from the one or more slave access devices (200, 200’) into a combined upstream optical signal, wherein the combined upstream optical signal is a to-be-amplified upstream optical signal.

2. The master access device (100) according to claim 1, wherein the one or more optical amplifiers (101) comprise a first downstream optical amplifier (1011), configured to: amplify a first downstream optical signal from a first passive optical network.

3. The master access device (100) according to claim 2, wherein the one or more optical amplifiers further (101) comprise a second downstream optical amplifier (1012), configured to: amplify a second downstream optical signal from a second passive optical network, wherein the second passive optical network is different from the first passive optical network.

4. The master access device (100) according to claim 3, further comprising: a first multiplexer / demultiplexer, Mux / Demux, module (103), configured to separate a received optical stream into the first downstream optical signal and the second downstream optical signal; and a second Mux / Demux module (104), configured to combine the amplified first downstream optical signal and the amplified second downstream optical signal into an amplified optical stream.

5. The master access device (100) according to one of the claims 2 to 4, wherein the one or more optical amplifiers (101) further comprise a first upstream optical amplifier (1013), configured to: amplify a first upstream optical signal.

6. The master access device (100) according to claim 5, wherein the one or more optical amplifiers (101) further comprise a second upstream optical amplifier (1014), configured to: amplify a second upstream optical signal.

7. The master access device (100) according to claim 6, wherein the first Mux / Demux module (103) is further configured to: combine the amplified first upstream optical signal and the amplified second upstream optical signal into an amplified upstream optical stream, and output the amplified upstream optical stream to the first passive optical network and / or the second passive optical network.

8. The master access device (100) according to one of the claims 5 to 7, further comprising a first control module (105), configured to: control whether to turn on or turn off the first upstream optical amplifier (1013), and / or the second upstream optical amplifier (1014).

9. The master access device (100) according to claim 8, wherein the first control module (105) is further configured to: turn on the first upstream optical amplifier (1013) and / or the second upstream optical amplifier (1014) only when any of the one or more slave access devices (200, 200’) is transmitting to the master access device (100).

10. The master access device (100) according to one of the claims 68 to 9, wherein the second Mux / Demux module (104) is further configured to: separate the combined upstream optical signal into the first upstream optical signal and the second upstream optical signal.

11. The master access device (100) according to one of the claims 1 to 10, further comprising a second control module (106), configured to: control a gain for each of the one or more optical amplifiers (101).

12. The master access device (100) according to claim 11, wherein the second control module (106) is further configured to: control the gain for each of the one or more optical amplifiers (101) based on a loss of the optical splitter / combiner module (102).

13. The master access device (100) according to claim 11 or 12, wherein the optical splitter / combiner module (102) is further configured to: provide a split optical signal to the second control module (106).

14. The master access device (100) according to one of the claims 11 to 13 and claim 8 or 9, wherein the second control module (106) is further configured to: provide transmitting timing information of the one or more slave access devices (200, 200’) to the first control module (105).

15. The master access device (100) according to claim 14, wherein the first control module (105) is further configured to: turn on or turn off the first upstream optical amplifier (1013) and / or the second upstream optical amplifier (1014) based on the transmitting timing information received from the second control module (106).

16. The master access device (100) according to one of the claims 1 to 13, further comprising an optical detector (107), configured to: detect whether there is an upstream optical signal from the one or more slave access devices (200, 200’).

17. The master access device (100) according to claim 16 and claim 8 or 9, wherein the optical detector (107) is further configured to: provide a detection result to the first control module (105), and the first control module (105) is further configured to:turn on or turn off the first upstream optical amplifier (1013) and / or the second upstream optical amplifier (1014) based on the detection result.

18. An optical communication system (1) comprising one or more passive optical networks, and one or more indoor optical networks (10), wherein each indoor optical network (10) comprises a master access device (100) according to one of the claims 1 to 17 and comprises one or more slave access devices (200, 200’) optically coupled to the master access device (100).

19. A method for operating a master access device (100) for an indoor optical network (10), wherein the indoor optical network (10) comprises one or more slave access devices (200, 200’) optically coupled to the master access device (100), and wherein the method comprises: amplifying a downstream optical signal and / or amplifying an upstream optical signal; splitting the amplified downstream optical signal into one or more split optical signals, and sending the one or more split optical signals to the one or more slave access devices (200, 200’); and / or combining one or more upstream optical signals from the one or more slave access devices (200, 200’) into a combined upstream optical signal, wherein the combined upstream optical signal is a to-be-amplified upstream optical signal.

20. A computer program comprising instructions which, when the program is executed by a computer, for example a processor of a master access device (100) according to one of the claims 1 to 18, cause the computer to perform the method according to claim 19.

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