An adapter assembly

Abstract

An adapter assembly for a telecommunications unit (220). The adapter assembly comprises a connector (237) for coupling to the telecommunications unit; an optical-electrical arrangement (235, 335) coupled to the connector, the optical-electrical arrangement comprising an optical module (345-1) to convert between optical and electrical signals; a first optical fiber terminal (233-1) for engaging a first optical fiber termination (250B) and a second optical fiber terminal (233-2) for engaging a second optical fiber termination (250R), the first and the second optical fiber terminations coupled to the optical-electrical arrangement (235). The optical- electrical arrangement (235) is configured to separate a downlink signal received at the first optical fiber terminal (233-1) into respective downlink signals at the connector (237) and the second optical fiber terminal (233-2), and to combine the uplink signals received at the connector (237) and the second optical fiber terminal (233-2) into an uplink signal at the first optical fiber terminal (233-1).

Description

[0001] An adapter assembly

[0002] Technical Field

[0003] The present disclosure relates to an adapter assembly for coupling an optical module to an outdoor active unit, such as a radio unit.

[0004] Background

[0005] In Radio Access Networks (RAN), Radio Units (RU) are typically connected to local or remote Baseband Units (BBU) by means of transport links (e.g. optical fibers) carrying 10G, 25G, 50G and future higher rates - known as the Fronthaul. If the RU and the BBU are co-located, the architecture is considered as a Distributed RAN (D-RAN), if they are dislocated (typically at a distance up to 20km) the architecture is considered as a Centralized RAN (C-RAN).

[0006] RUs might have one or more Fronthaul interfaces based on their RAN capacity. These interfaces are typically CPRI (TDM-like) or eCPRI (Ethernet Packet based) interfaces which are carried via optical fibers. The optical fibers may be terminated in connectors having optical modules plugged into MSA (multi-source agreement) cages of the RU. The optical modules convert between optical and electrical signals and may be implemented as standardized small pluggable form (SFP) transceivers.

[0007] Due to fiber scarcity and fiber costs, multiple Fronthaul interfaces or ports may be multiplexed over a single fiber using WDM lambda multiplexing in the optical domain. In some cases, this allows a single fiber to support more than one RU, for example where two or more RU are co-located. Here, one RU coupled to the single fiber may interface with an allocated Fronthaul interface or port whilst acting to cascade other Fronthaul interfaces to downstream RU. To enable this, the RU coupled to the optical fiber from the BBU may be configured to convert optical signals corresponding to the Fronthaul ports into electrical signals which are internally processed to separate the Fronthaul port allocated to the Rll. The other Fronthaul ports may then be re-packaged for transmission to downstream Rll via other optical fibers using respective optical modules.

[0008] Optical modules are very sensitive to the temperature of the Rll’s which poses challenging constraints for a design aiming to provide enclosures as compact as possible. Rll are often deployed in outdoor scenarios, such as mounted on poles, or at the top of buildings or towers. In such scenarios, the Rll can be exposed to weather and outdoor environmental conditions. For this reason, the Rll are typically installed within enclosures designed to protect them against the weather and environmental conditions they may experience. For example, the enclosures may be designs to IP65 standards or greater. In some situations, such enclosures are camouflaged to respect the local rules for deployment in urban environments.

[0009] When Rll are installed within such an enclosure, the internal temperature of the Rll can reach high temperatures. For example, the Rll may reach a temperature above 85 degrees Celsius. In particular, such internal temperatures can be reached when the RRU is installed within an enclosure in an environment where the temperature can reach or exceed 50 degrees Celsius, even for short periods.

[0010] Normally, the Rll to be installed within such enclosures are designed to be fan-less. However, even when a fan is present, the optical modules, e.g. pluggable optical modules, installed in the radio unit may not benefit from any airflow. Furthermore, the optical modules are typically positioned close to other high temperature components of the radio units, such as the power supply and its dissipaters, which can further increase the temperature of the optical modules.

[0011] Pluggable optical modules and, in particular, pluggable WDM optical modules can be sensitive to circuitry temperature, because temperature can affect the modulation of wavelength by the module. For this reason, most commercially available optical modules are limited to operating in environmental conditions in which the temperature is between -40 and +85 degrees Celsius.

[0012] The sensitivity of pluggable optical modules to temperature can limit the possibility of providing WDM pluggable optical modules in radio units in some countries where the ambient temperature can reach or exceed desirable operating temperatures of the radio units, and / or where the regulatory camouflage prevents sufficient passive air circulation around the radio unit.

[0013] Summary

[0014] According to an aspect of the present disclosure, there is provided an adapter assembly for a telecommunications unit. The adapter assembly comprises a connector for coupling to the telecommunications unit; an optical-electrical arrangement coupled to the connector, the optical-electrical arrangement comprising an optical module to convert between optical and electrical signals; a first optical fiber terminal for engaging a first optical fiber termination and a second optical fiber terminal for engaging a second optical fiber termination, the first and the second optical fiber terminations coupled to the optical- electrical arrangement. The optical-electrical arrangement is configured to separate a downlink signal received at the first optical fiber terminal into respective downlink signals at the connector and the second optical fiber terminal, and to combine the uplink signals received at the connector and the second optical fiber terminal into an uplink signal at the first optical fiber terminal.

[0015] In some examples, the optical-electrical arrangement comprises a second optical module and a separation circuit, wherein the first optical module is coupled between the first optical fiber terminal and the separation circuit, and the second optical module is coupled between the second optical fiber terminal and the separation circuit, and the separation circuit is coupled to the connector. Example adapter assemblies provide a number of potential advantages, depending on implementation. Examples may simplify installation of a Fronthaul network in a RAN, enable port splitting of RF ports for co-located or the same Rll, and readily enabling rate conversion, all whilst interfacing with standard RF ports and optical cables. The installation can be managed without external tools for re-configuring an Rll and without the associated security risks. Some examples enable installation of two optical modules in the space normally reserved for a single optical module, whilst managing heating and EMI. The use of the two optical modules in a single adapter assembly allows for cascading of higher traffic rates over different transceivers, increasing the capacity of the transport link.

[0016] According to another aspect, there is provided a system comprising a telecommunications unit and an adapter assembly as previously defined and coupled to the telecommunications unit.

[0017] To avoid unnecessary duplication of effort and repetition of text in the specification, certain features are described in relation to only one or several aspects or embodiments of the invention. However, it is to be understood that, where it is technically possible, features described in relation to any aspect or embodiment of the invention may also be used with any other aspect or embodiment of the invention.

[0018] Brief Description of the Drawings

[0019] For a better understanding of the present invention, and to show more clearly how it may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which:

[0020] Figure 1 is a schematic view of a radio access network (RAN) according to an example;

[0021] Figure 2 is a schematic view of a radio unit (Rll) and adapter assembly according to an example; Figure 3 is a schematic view of an adapter assembly according of an example;

[0022] Figure 4 illustrates fronthaul interface processing using an adapter assembly according to an example;

[0023] Figure 5 illustrates the arrangement of the internal parts of an adapter assembly according to an example; and

[0024] Figure 6 illustrates the external parts of the adapter assembly of Figure 5.

[0025] Detailed Description

[0026] Examples of the present disclosure propose adapter assemblies for facilitating cascading of Radio Units (RU) in a Radio Access Network (RAN) using optical fibers to couple the RU to a Baseband Unit (BBU). Example adapter assemblies may additionally or alternatively be used to couple multiple ports of one RU to a BBU, which may be used when individual RU ports have lower capacity than that available via the optical fiber. These adapter assemblies simplify the physical connection of the optical fibers with the RU whilst minimizing heating of critical components such as optical modules.

[0027] Figure 1 is a schematic view of a RAN according to an example. The RAN 100 comprises a core node 105 coupled to a number of BBU 110, some or which may be co-located in a pool 112 of BBU. The core node 105 may be provided in a central office and enable interconnection with other networks, such as the Internet. The BBU 110 are coupled to RU 120a-1 , 120b via optical fiber 150. The RRU 120a-1 , 120b may be mounted on a pole 115a, 115b having an antenna and other equipment. In some cases, more than one RRU 120a-1 , 120a-2 may be co-located as shown. An adapter assembly according to an example may be employed to facilitate physical connection of optical fibers between RU and BBU and in some cases between Rll and other Rll.

[0028] Figure 2 is a schematic view of a Rll and adapter assembly according to an example. The illustrated arrangement 200 comprises a Rll 220 connected to an adapter assembly 230 which terminates an optical fiber 250B from a BBU and an optical fiber 250R from another RU port. The other RU port may be another port on the same RU or an RU port on another RU, such as the second co-located RU 120a-2 of Figure 1 .

[0029] The RU 220 comprises radio and digital signal processing circuitry 224, radio frequency amplifying and receiving circuitry 226, and power circuitry 228. The power circuitry provides power for the other circuitry 224, 226, as well as the adapter assembly 230 via a standard connection, such as an MSA connector. The RF amplifying and receiving circuitry 226 is coupled to an antenna and is configured to amplify radio frequency (RF) signals to be transmitted from the antenna and to amplify RF signals received by the antenna. The radio and digital signal processing circuitry 224 is configured to convert between baseband and RF signals and to process baseband and control signals. The radio and digital processing circuitry 224 is coupled to the adapter assembly 230 via an electrical signal connection such as an MSA plug and socket / cage.

[0030] The adapter assembly 230 converts between the optical and electrical domains to enable communication between the RU and the BBU or other RU ports via optical fiber 250B, 250R. The adapter assembly 230 comprises a connector 237, an optical-electrical arrangement 235, a first optical fiber terminal 233-1 and a second optical fiber terminal 233-2. The connector 237 may be an MSA plug to physically interface with an MSA socket in the RU 220. The MSA connector may be configured as an SFP (small form-factor pluggable) transceiver plug for physically engaging with an SFP cage in the RU 220. The first optical fiber terminal 233-1 is configured for engaging the termination of a first optical fiber 250B and the second optical fiber terminal 233-1 is configured for engaging the termination of a second optical fiber 250R. The first and second optical fiber terminals 233-1 , 233-2 may be configured according to implementation specific requirements, for example as FullAXS™ connectors.

[0031] The optical-electrical arrangement 235 is configured to separate a downlink signal received at the first (or second) optical fiber terminal 233-1 (233-2) into respective downlink signals at the connector 237 and the second (first) optical fiber terminal 233-2 (233-1), and to combine the uplink signals received at the connector 237 and the second (first) optical fiber terminal 233-2 (233-1 ) into an uplink signal at the first (second) optical fiber terminal 233-1 (233-2). The optical-electrical arrangement 235 comprises one or more optical modules or transceivers to convert between optical and electrical signals. The optical modules may be implemented as standardized small form-factor pluggable transceivers (SFP) and the adapter assembly 230 may comprise internal SFP cages for installing SFP optical modules. In some examples, quad small form-factor pluggable transceivers (QSFP) may be employed. SFP, QSFP or other types of optical modules may be implemented for handling WDM (wave division multiplex) optical signals or Grey (single wavelength) optical signals. Optical modules may be used for converting between WDM and Grey optical signals within the adapter assembly in some examples.

[0032] In some examples, the optical-electrical arrangement 235 may comprise an optical module coupled to the connector 237 in order to convert between optical signals at both the first and second optical fiber terminals 233-1 , 233- 2 and electrical signals at the connector 237. This allows optical signals transmitted on an optical fiber 250B connected between the BBU and the adapter assembly 230 to be received by the radio unit 220, as well as to be passed on to a downstream Rll port using another optical fiber 250R connected between the adapter assembly 230 and the downstream Rll port. In some examples, an optical multiplexer (MUX) may be used to separate optical signals on different wavelengths, with one wavelength being used for the RU port to which the adapter assembly is connected and another wavelength for the downstream RU port. In another example, the signals for the different Rll ports may be separated in other ways such as using time division multiplexing or a packet routing. This could be implemented by converting a Grey optical signal into electrical signals which are processed by electrical processing circuitry in the adapter assembly to separate signals for the Rll port to which the adapter assembly is connected. The Grey optical signal may also be passed to the downstream Rll port where similar electrical processing may be performed to separate the signals for the downstream Rll port. The downstream Rll port may be another MSA SFP socket on the same Rll 220 or on a different Rll.

[0033] The use of an adapter assembly 230 which terminates two optical fibers 250B, 250R and connects to a single socket or cage of an Rll 220, simplifies the cabling and installation required for configuring cascading Rll at remote RAN locations. In some examples using optical signals on different wavelengths, the receiving / transmitting capacity of an Rll may be increased by directing optical signals on different wavelengths to different ports on the same Rll by using the adapter assembly. Further advantages associated with this example and other examples will become apparent from the discussion below.

[0034] In other examples, the optical-electrical arrangement 235 may comprise an optical module coupled to the first optical fiber terminal 233-1 and a second optical module coupled to the second optical fiber terminal 233-2, in order to separately convert between optical signals at the first and second optical fiber terminals 233-1 , 233-2 and respective electrical signals. Further processing of the electrical signals within the optical-electrical arrangement 235 may provide additional functionality such as rate conversion as described in more detail below. An example of an adapter assembly of this type is described with respect to Figure 3.

[0035] Figure 3 is a schematic view of an adapter assembly according of an example. The adapter assembly 330 comprises a connector 337, an optical- electrical arrangement 335 and first and second optical fiber terminals 333-1 , 333-2. The connector 337 may be any suitable connector configured for coupling to a radio unit, such as the connectors described with respect to Figure 2. The optical fiber terminals 333-1 , 333-2 may be configured to terminate respective optical fibers 350B, 350R and may be any suitable components such as those described with respect to Figure 2. The optical fibers 350B, 350R may be enclosed within a common optical cable 355 for coupling to the adapter assembly 330, the optical cable 355 then separating to carry the respective optical fibers 350B, 350R to different destinations.

[0036] The optical-electrical arrangement 335 is coupled to the first and second fiber terminals 333-1 , 333-2 and to the connector 337. The optical-electrical arrangement 335 comprises a first optical module 345-1 coupled to the first optical fiber terminal 333-1 and a second optical module 345-1 coupled to the second optical fiber terminal 333-2. The optical modules 345-1 , 345-2 may be any suitable components such as those described with respect to Figure 2. The optical-electrical arrangement also comprises a separation circuit 340 coupled to the first and second optical modules 345-1 , 345-2 and to the connector 337. The separation circuit 340 which may be implemented as an ASIC or any other suitable electrical processing circuit, and may be configured in different ways to separate optical downlink signals received on a first optical fiber terminal 333-1 into respective electrical downlink signals for the connector 337 and respective optical downlink signals for the second optical fiber terminal 333-2. Similarly, the separation circuit 340 may be configured in different ways to combine electrical uplink signals from the connector 337 and optical uplink signals from the second optical fiber terminal 333-2 into an optical uplink signal for the first optical fiber terminal 333-1 .

[0037] In some examples, the separation circuit 340 may be implemented as a Layer 2 switch (e.g. Ethernet), a Layer 3 router (e.g. IP), a time division multiplexer / demultiplexer (TDM) circuit. The separation circuit 340 may also implement rate conversion, for example converting a 50G downlink signal received by the first optical module 345-1 into two 25G downlink signals for the converter 337 and the second optical module 345-2. This may be implemented for example using buffering and queuing of received packets at a high rate and transmitting these over the two downlink channels at a lower rate.

[0038] Figure 4 illustrates an example of a separation circuit 340 configured as an Ethernet switch and for rate conversion. The Ethernet switch 440 is connected to respective optical modules 445-1 , 445-2 and a connector 437 for connecting to an RU. A first optical module 445-1 is coupled between a BBU and the Ethernet switch 440 and is implemented using an SFP56 which is capable of converting between electrical and optical signals at 50G. A second optical module 445-2 is coupled between the Ethernet switch 440 and another Rll port of the same Rll or to another Rll. The second optical module is implemented using an SFP28 which is capable of converting between electrical and optical signals at 25G.

[0039] The connector 437 may be configured physically as an SFP28 transceiver plug for mechanical and electrical coupling to the Rll, but without conversion between electrical and optical signals - this is illustrated using SFP28’. Reference SRP28’ also indicates that the electrical Rll port to which the connector 437 interface has a rate of 25G. In other examples, an optical port may be required for connection to the Rll, and in this situation the connector may be configured to include an optical module, converting electrical signals from the separation circuit 440 into optical signals for the Rll.

[0040] Downlink packets 460 are illustrated, however for simplicity uplink packets are omitted. These downlink packets 460 are simplified and are distinguished using P1 and P2, with their destination address denoted as RU_X for the Rll to which the adapted assembly is connected and RU_Y for a downstream Rll port which could be on the same Rll or a cascaded Rll. The downlink packets 460 are transmitted as 50G optical signals over an optical fiber coupled between a first optical module SFP56 445-1 and a BBU. The SFP56 445-1 converts the packets into electrical signals for forwarding to the Ethernet switch 440. The Ethernet switch separates the packets into respective downlink directions, with the “P1 , RU_X” packet being forwarded to the connector 437 and the “P2, RU_Y” packet being forwarded to second optical module SFP28445-2. The second optical module 445-2 is coupled to a downstream RU port and converts the “P2, RU_Y” packet into optical signals at 25G for transmission to that downstream Rll port. Similar processing but in reverse occurs for uplink signals and packets.

[0041] This example allows for port splitting by splitting a single 50G optical signal into 2x25G signals. One of these 25G signals is for coupling to the Rll port to which the adapter assembly is connected, and the other 25G signal is an optical signal for a downstream Rll port. The 25G optical signal may be carried by an optical fiber which is also terminated in an adapter assembly for coupling to the downstream Rll port. It is possible that this downstream 25G signal may be further split for additional cascading for additional downstream Rll ports. The downstream Rll port(s) may be on the same Rll or a different RU or RUs.

[0042] Although not illustrated for simplicity, a corresponding arrangement may exist for uplink packets from RU sources towards the BBU. In some examples the uplink packets may be queued in a separation circuit 340, 440 for forwarding to more than one BBU, using TDM or another suitable multiplexing mechanism over the optical fiber 350B.

[0043] In some examples, there may be no rate conversion and the two optical and the electrical signals may be at the same rate, for example 50G. Different rates or combinations of rates may be used, for example, 1 G, 10G, 25G, 50G, 100G and so on. In some examples, the adapter assembly may interface with non-RU telecommunications units. In some examples, the separation circuit may be implemented using an ASIC or another type of processing circuit. Such processing circuitry may be used to implement additional functions such as operations and maintenance (O&M), signal monitoring such as FEC (forward error correction), PRBS (pseudo random binary sequence) generation and loopbacks or other observability features.

[0044] The examples allow considerable flexibility and simplicity in the installation and configuration of a Fronthaul network for a RAN. For example, the full 50G rate of a BBU may be utilized by a RU where each port is limited to 25G. By using an adapter assembly with a 50G first optical module 445-1 and a 25G second optical module 445-2, the 50G signal may be split into 2x25G signals, one of these 25G signals provided to an Rll port via the connector 437 to which the adapter assembly is connected, and the other 25G signal may be provided to another 25G port on the same Rll via the second optical module 445-2. The optical fiber coupled to the second optical module 445-2 may terminate in a similar or different adapter assembly, or a standard connector. Without the use of the adapter assembly, the Rll would only be able to receive / transmit at 25G, thereby limiting its capacity.

[0045] In another example, the 50G signal may be used to communicate with two co-located Rll using port splitting in which each Rll receives / transmits a 25G signal. The optical fiber coupled between the first and second Rll may terminate in a similar or different adapter assembly, or a standard connector. Without the adapter assembly, if the first Rll is 50G capable, it may be possible to re-configure the Rll to receive 50G signal, separate this internally, and output a 25G signal for a downstream Rll. However, this is complicated and time consuming and may be prone to error and security risks. Using an adapter assembly according to an example, the RUs do not need to be internally re-configured and the architecture may be simply implemented using the adapter assembly and fiber installation.

[0046] The use of optical modules and in particular two optical modules may render the adapter assembly susceptible to adverse heat effects. Figures 5-6 illustrate an example mechanical configuration of an adapter assembly to mitigate the effects of heat generated by the optical modules, the nearby RU circuitry and environmental conditions such as high ambient temperature and / or humidity. The mechanical configuration also facilitates simple installation of optical cables.

[0047] Figure 5 illustrates the arrangement of the internal parts of an adapter assembly according to an example. Reference is also made to Figure 6 which illustrates the arrangement of external parts of the adapter assembly of Figure 5. Common parts have the same reference numerals.

[0048] Referring first to Figure 5, the internal parts 500 of the adapter assembly comprise a circuit board 560 onto which are mounted two optical modules 545-1 , 545-2, and an ASIC or other processing device 540 to implement a separation circuit. The optical modules 545-1 , 545-2 are arranged “belly-to- belly” on either side of the circuit board 560 as shown, and may share circuit board connections and a common power supply lane. This configuration facilitates a compact adapter assembly that is similar to existing plug connections and also minimizes the length of the circuit board 560, thereby reducing the need for regeneration of signals whilst also providing enough space to host shared electronic circuitry 540.

[0049] The optical modules 545-1 , 545-2 may be SFP transceivers, such as SFP56 and SFP28 for example. The adapter assembly may comprise SFP cages for receiving the optical modules to increase the adaptability of the adapter assembly, for example to swap different rate SFP transceivers depending on installation requirements.

[0050] Optical fiber terminals 533-1 , 533-2 are connected to and arranged at an end of respective optical modules 545-1 , 545-2. In some examples, the optical fiber terminals 533-1 , 533-2 may be configured as FullAXS™ sockets or cages which are arranged in a common plane perpendicular to the longitudinal direction of the adapter assembly, in order to facilitate a compact adapter assembly and to simplify connection of optical fibers.

[0051] A connector 537 is formed about one end of the circuit board and is configured to present an external shape and dimensions corresponding to an SFP transceiver for engaging within an SFP cage or socket forming the Rll port.

[0052] Referring now to Figure 6, the external parts 600 of the adapter assembly of Figure 5 are illustrated in four details A, B, C, D. Detail A illustrates a side view of the adapter assembly; detail B illustrates an end view of the left end of the adapter assembly of detail A; detail C illustrates a section view of a heat dissipator body of the adapter assembly of detail A; and detail D illustrates an optical fiber termination connector to be added in use to the adapter assembly of detail A.

[0053] The adapter assembly comprise a heat dissipator body 665 having a recess for receiving the two optical modules 545-1 , 545-2. When installed, the optical modules are in thermal communication with the heat dissipator body 665. This may be implemented by arranging the metallic parts of the optical modules to be in physical and thermal contact with the heat dissipator body. Where used, SFP cages holding SFP optical modules may alternatively or additionally be in contact with the heat dissipator body.

[0054] The heat dissipator body may be formed of any suitable thermally conducting and corrosion resistant material such as aluminum. The heat dissipator body 665 comprises one or more heat dissipation structures 666 configured to dissipate heat from the optical modules into an environment around the heat dissipator body 665. The heat dissipation structures 666 may be fins or similar metallic parts arranged around part or all of the surface of the heat dissipator body 665. For simplicity, only a small number of such fins are illustrated, however it will be appreciated that these may extend around a greater part of (including fully around) the circumference of the heat dissipation body.

[0055] The adapter assembly comprises a mechanical coupler 667 coupled in use to the heat dissipator body 665. Removal of the mechanical coupler 667 may allow access to the recess of the heat dissipator body. The mechanical coupler 667 comprises the first and second optical fiber terminals 633-1 , 633- 2 which are mechanically arranged to allow optical fibers 653-1 , 653-2 to be easily engaged. The mechanical coupler 667 may be formed of any suitable material, such as a plastics material. An EMI (electromagnetic interference) ring 678 may be fitted between the mechanical coupler 667 and the heat dissipator body 665, or within one end of the heat dissipator body 665. The EMI ring surrounds both optical modules and reduces EMI from the optical modules, which may otherwise affect other nearby electronics components. The EMI ring may be fully metallic which assists with heat conduction from the optical modules to the heat dissipator body.

[0056] The optical fibers 653-1 , 653-2 are normally terminated in an optical fiber termination connector 669, having been enclosed within an optical cable 655 towards a destination node such as a BBU or another Rll. The mechanical coupler 667 is also configured to allow a simple and fast coupling with the optical fiber termination connector 669 in order to couple the optical fibers 653-1 , 653-2 with corresponding optical fiber terminals 533-1 , 533-2.

[0057] The circuit board 560 extends out of the recess of the heat dissipator body 665 away from the direction of the mechanical coupler 667. The circuit board includes the separation circuit such as an ASIC 540, and is protected by a connector coupling 668. The connector coupling 668 may be formed of any suitable material such as plastics material and is coupled at one end to the heat dissipator body 665. At the other end of the connector coupling 668, the connector 537 protrudes distal to the optical fiber terminals 533-1 , 533-2, providing an elongate shape for the adapter arrangement which avoids interfering with separate connections to other nearby sockets of the Rll.

[0058] In some examples, the connector 537 comprises one or more recesses 674 on the surface to reduce the mechanical contact area 672 between the connector 537 and the socket or cage of the Rll into which the connector is plugged or engaged. This reduces heat conduction from the Rll into the adapter assembly. External parts of the connector may also be made of plastics material to further limit the transfer of heat from the Rll into the adapter assembly. The adapter assemblies of the examples provide a number of advantages including simplifying installation of a Fronthaul network in a RAN, enabling port splitting of RF ports for co-located or the same Rll, and readily enabling rate conversion, all whilst interfacing with standard RF ports and optical cables. The adapter assembly enables the installation of two optical modules in the space normally reserved for a single optical module. The installation can be managed without external tools for re-configuring an Rll and without the associated security risks. The use of the two optical modules in a single adapter assembly allows for cascading of higher traffic rates over different transceivers, increasing the capacity of the transport link. The additional circuitry within the adapter assembly may also be employed to provide additional functionality such as performing monitoring and O&M. Additional advantages include a small footprint compatible with standard cable connector areas of Rll, efficient heat management, reduced EMI and power consumption.

[0059] Whilst the examples have been described in the context of the adapter assemblies connecting to Rll ports, they may also be used with other types of telecommunications equipment. Examples include Outdoor Cell Site Routers, Radio Processor Units, FWA (fixed wireless access) systems.

[0060] Generally, all terms used herein are to be interpreted according to their ordinary meaning in the relevant technical field, unless a different meaning is clearly given and / or is implied from the context in which it is used. All references to a / an / the element, apparatus, component, means, step, etc. are to be interpreted openly as referring to at least one instance of the element, apparatus, component, means, step, etc., unless explicitly stated otherwise. The steps of any methods disclosed herein do not have to be performed in the exact order disclosed, unless a step is explicitly described as following or preceding another step and / or where it is implicit that a step must follow or precede another step. Any feature of any of the embodiments disclosed herein may be applied to any other embodiment, wherever appropriate. Likewise, any advantage of any of the embodiments may apply to any other embodiments, and vice versa. Other objectives, features and advantages of the enclosed embodiments will be apparent from the following description.

Claims

CLAIMS1. An adapter assembly for a telecommunications unit, the adapter assembly comprising: a connector for coupling to the telecommunications unit; an optical-electrical arrangement coupled to the connector, the optical- electrical arrangement comprising an optical module to convert between optical and electrical signals; a first optical fiber terminal for engaging a first optical fiber termination and a second optical fiber terminal for engaging a second optical fiber termination, the first and the second optical fiber terminations coupled to the optical-electrical arrangement; wherein the optical-electrical arrangement is configured to separate a downlink signal received at the first optical fiber terminal into respective downlink signals at the connector and the second optical fiber terminal, and to combine the uplink signals received at the connector and the second optical fiber terminal into an uplink signal at the first optical fiber terminal.

2. The adapter assembly of claim 1 , wherein the optical-electrical arrangement comprises a second optical module and a separation circuit, wherein the first optical module is coupled between the first optical fiber terminal and the separation circuit, and the second optical module is coupled between the second optical fiber terminal and the separation circuit, and the separation circuit is coupled to the connector.

3. The adapter assembly of claim 2, wherein the first and second optical modules are respective small form factor pluggable transceivers, SFP, or quad small form factor pluggable transceivers, QSFP, and the connector is adapted to interface with an SFP port or a QSFP port in the telecommunications unit.

4. The adapter assembly of any one of claims 1 to 3, wherein the optical- electrical arrangement comprises one or more of the following: a Layer 2 switch; a L3 router, a time division multiplexing, TDM, circuit or an alternative combiner and selection function5. The adapter assembly of any one of claims 1 to 4, wherein the optical- electrical arrangement comprises an Application Specific Integrated Circuit, ASIC, configured to implement an Ethernet switch.

6. The adapter assembly of claim 1 , wherein the optical module is coupled between the connector and a separation circuit, the separation circuit being coupled to the first optical fiber terminal and the second optical fiber terminal.

7. The adapter assembly of any one of claims 1 to 6, comprising one or more WDM to Grey optical modules coupled to the first optical fiber terminal.

8. The adaptor assembly of any one of claims 1 to 7, wherein the optical- electrical arrangement comprises a rate converter to convert between a first rate of a signal at the first optical fiber terminal to a second rate of a signal at the second optical fiber terminal or the connector.

9. The adaptor assembly of any one of claims 1 to 8, wherein the optical electrical arrangement is configured to separate an eCPRI or CPRI signal at the first optical fiber terminal into a eCPRI or CPRI signal at the connector and a eCPRI or CPRI signal at the second optical fiber terminal, and to combine a eCPRI or CPRI signal received at the connector and an eCPRI or CPRI signal at the second optical fiber terminal into a eCPRI or CPRI signal at the first optical fiber terminal.

10. The adapter assembly of claim 9, wherein the eCPRI or CPRI signal at the first optical fiber terminal is a 50G eCPRI or CPRI signal and the eCPRI or CPRI signals at the connector and the second optical fiber terminal are 25G eCPRI or CPRI signals11. The adapter assembly of any one of claims 1 to 10, wherein the connector is mechanically configured to interface with a SFP port in the telecommunications unit.

12. The adapter assembly of claim 11 , wherein the connector comprises a non-metal housing arranged about an electrical contact interface, the electrical contact interface adapted to electrically connect with the SFP port and having a recess.

13. The adaptor assembly of any one preceding claim when dependent on claim 2, comprising a heat dissipater body having a recess for receiving two optical modules, such that the optical modules are in thermal communication with the heat dissipator body, and one or more heat dissipation structures configured to dissipate heat from the optical modules into an environment around the heat dissipater body.

14. The adaptor assembly of claim 13, comprising a mechanical coupler coupled to the heat dissipator body and configured to couple to an optical connector having optical terminations terminating a plurality of optical fibers, the mechanical coupler having the first and second optical fiber terminals arranged distal to the connector and configured to receive the optical terminations.

15. The adapter assembly of claim 13 or 14 when dependent on claim 2, wherein the first and the second optical modules are physically arranged belly- to-belly within the recess of the heat dissipater body.

16. The adapter assembly of any one of claims 1 to 13, wherein the telecommunications unit is a Radio Access Network, RAN, node.

17. A system comprising: a telecommunications unit; the adapter assembly of any one of claims 1 to 16 and coupled to the telecommunications unit.

18. The system of claim 17, comprising: a second telecommunications unit; a first optical fiber engaged with the adapter assembly, the first optical fiber coupled to a base band unit; a second optical fiber engaged with the adapter assembly, the second optical fiber coupled to the second telecommunications unit.

19. The system of claim 17, wherein the adapter assembly is coupled to a first port of the telecommunications unit, and the system comprising: a first optical fiber engaged with the adapter assembly, the first optical fiber coupled to a base band unit; a second optical fiber engaged with the adapter assembly, the second optical fiber coupled to a second port of the telecommunications unit.

20. The system of claim 17, comprising:a first optical fiber engaged with the adapter assembly, the first optical fiber coupled to a base band unit; a second optical fiber engaged with the adapter assembly, the second optical fiber coupled to a second adapter assembly according to any one of claims 1 to 16.

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