Patent Publication Number: US-2023155860-A1

Title: Configuring fronthaul link

Description:
TECHNICAL FIELD 
     The present disclosure relates to a method of a first radio equipment device of configuring a fronthaul communication link established with a second radio equipment device, and a first radio equipment device performing the method. 
     BACKGROUND 
     Fronthaul networks connect various devices such as baseband units, switches, converters with radio units. A fronthaul link is a point-to-point connection between a baseband unit and a radio unit, between two radio units, between a converter and a radio unit or any other combination. This equipment may support a multitude of bitrates (1.22G, 2.45G, 9.8G. 10.1G, 10G, 24.3G, 25G etc.), protocols such as a Common Public Radio Interface (CPRI), Ethernet, etc., and different Forward Error Correction (FEC) methods, for instance no FEC, Reed Solomon (RS) and KR-FEC. Both ends of a link must use the same bitrate, protocol and FEC standard simultaneously to become operational. 
     The CPRI protocol specifies how bitrates are shifted with a i-second cycle on master ports and a 4-second cycle on slave ports. Master and Slave will eventually use the common bitrate and then connection can be established. However, there is not guarantee that a preferred bitrate is used in that initial connection. And the CPRI protocol standard does not provide a means to guarantee that the connection has a preferred bitrate. 
     SUMMARY 
     One objective is to solve, or at least mitigate, this problem in the art and thus to provide an improved method of a first radio equipment device of configuring a fronthaul communication link established with a second radio equipment device. 
     This objective is attained in a first aspect of the invention by a method of a first radio equipment device of configuring a fronthaul communication link established with a second radio equipment device. The method comprises configuring the first radio equipment device to receive data over the fronthaul communication link at a selected bitrate with a selected communication protocol type, detecting if bitrate of, and communication protocol type used for, data received over the fronthaul communication link match the selected bitrate and the selected communication protocol type for which the first radio equipment device is configured to receive data, wherein at least one of the selected bitrate and the selected communication protocol type for which the first radio equipment device is configured to receive data is adjusted until a match is detected, and selecting the bitrate and communication protocol type for which there is a match as the bitrate and communication protocol type with which data is communicated over the fronthaul communication link. 
     This objective is attained in a second aspect of the invention by a first radio equipment device configured to cause configuring of a fronthaul communication link established with a second radio equipment device. The first radio equipment device comprises a processing unit and a memory, which memory contains instructions executable by the processing unit, whereby the first radio equipment device is operative to configure the first radio equipment device to receive data over the fronthaul communication link at a selected bitrate with a selected communication protocol type, to detect if bitrate of, and communication protocol type used for, data received over the fronthaul communication link match the selected bitrate and the selected communication protocol type for which the first radio equipment device is configured to receive data, wherein at least one of the selected bitrate and the selected communication protocol type for which the first radio equipment device is configured to receive data is adjusted until a match is detected, and to select the bitrate and communication protocol type for which there is a match as the bitrate and communication protocol type with which data is communicated over the fronthaul communication link. 
     Hence in a first step, the first radio equipment (RE) is configured to be capable of receiving data over the fronthaul communication link at a selected bitrate, for instance 10 Gbps, and with a selected communication protocol type, such as Ethernet. 
     At the other end of the fronthaul communication link, the second RE will correspondingly be configured to receive data at a selected bitrate and with a selected communication protocol type. In this example, the second RE is configured to be capable of receiving the data at a bitrate of 25 Gbps over the fronthaul communication link using CPRI. 
     Now, it is not possible for the first RE and the second RE to exchange data over the link utilizing different data bitrates and/or different communication protocols. If so, it is not possible for one device to correctly interpret the data transmitted by the other. In other words, data received at other bitrates and/or with other communication protocols than what any one of the first RE and the second RE has been configured to receive will not be decoded correctly. 
     If at least one of the REs transmit data at the bitrate and with the protocol it is configured to received data over the link, it is possible to eventually find a match with the bitrate and protocol used by the other device, for instance by performing adjustments of the bitrate and/or protocol type at certain intervals until a matching combination of bitrate and protocol type is detected wherein the matching combination is selected for communication of data over the fronthaul link at both REs. 
     When a match is found, data can advantageously be exchanged over the fronthaul link using the matching combination of bitrate and protocol type and the fronthaul link has thus been successfully configured. 
     In an embodiment, the configuring of the first RE further comprises selecting type of Forward Error Correction (FEC) applied when receiving data over the fronthaul communication link, wherein the type of FEC applied is adjusted until the adjusted FEC matches the FEC applied to the data being received over the fronthaul communication link. 
     In an embodiment, when a match is found and data successfully may be exchanged over the adequately configured fronthaul link, the first RE transmits information over the fronthaul communication link indicating one or more combinations of bitrate and communication protocol type (and possibly FEC type) at which the first RE is capable of receiving and transmitting data over the fronthaul communication link. 
     By having the second RE sending the corresponding information, it is advantageously possible to select a preferred matching combination in case there are multiple matching combinations. For instance, the first RE may evaluate the matching combinations and select a combination of matching bitrate and protocol type which results in the highest bitrate for data being communicated over the fronthaul link. 
     A number of criteria may be evaluated for a preferred selection, such as 1) a highest matching bitrate, 2) a highest matching bitrate for a particular protocol, 3) a highest bitrate for a particular matching FEC, or just 4) a preferred protocol type regardless of bitrate, etc. Any matching combination is possible, even though it is likely in practice that a highest possible bitrate is used for communication over the fronthaul link. 
     In an embodiment, information indicating the selected matching combination is exchanged over the fronthaul communication link. 
     In an embodiment, protocol stack is established for communication over the fronthaul communication link. 
     In an embodiment, in case the second RE is not an equipment supporting negotiation of a preferred matching combination of bitrate and protocol type as has been described hereinabove, the first RE may start a timer upon transmitting the information to the second RE indicating its capabilities in terms of bitrate and protocol type (and possibly FEC type). If the second RE does not reply before the timer expires, the first RE will maintain the (only) matching combination which already has been selected. 
     Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. 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 method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Aspects and embodiments are now described, by way of example, with reference to the accompanying drawings, in which: 
         FIG.  1    illustrates two radio equipment devices establishing communication over a fronthaul link according to an embodiment; 
         FIG.  2    shows a signalling diagram illustrating a method of configuring the fronthaul communication link connecting the two radio equipment devices of  FIG.  1    according to an embodiment; 
         FIG.  3    shows a signalling diagram illustrating a method of configuring the fronthaul communication link connecting the two radio equipment devices of  FIG.  1    according to a further embodiment; 
         FIG.  4    illustrates the two radio equipment devices establishing communication over a respective fronthaul link with an intermediate unit being connected to the links between the two radio equipment devices according to an embodiment; 
         FIG.  5    shows a signalling diagram illustrating a method of configuring the fronthaul communication links connecting the two radio equipment devices of  FIG.  4    according to an embodiment; and 
         FIG.  6    illustrates a radio equipment device according to an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     The aspects of the present disclosure will now be described more fully hereinafter with reference to the accompanying drawings, in which certain embodiments of the invention are shown. 
     These aspects may, however, be embodied in many different forms and should not be construed as limiting; rather, these embodiments are provided by way of example so that this disclosure will be thorough and complete, and to fully convey the scope of all aspects of invention to those skilled in the art. Like numbers refer to like elements throughout the description. 
       FIG.  1    illustrates two radio equipment devices establishing communication over a fronthaul link according to an embodiment. 
     A first radio equipment device is referred to as Radio Equipment Control (REC) A  10 , being for instance a baseband unit (BBU), while a second radio equipment device is referred to as Radio Equipment (RE) A  20 , being for instance a radio unit in the form of e.g. a remote radio head (RRH). REC and RE are terms used in the CPRI standard and are exemplifying only; embodiments herein are applicable to other standards as well. The REC A  10  and RE A  20  connects over the fronthaul link  30 , being for instance a fibre optical link or electric cable connecting the two devices. The REC A  10  is commonly referred to as a master, while the RE A  20  is referred to as a slave. 
       FIG.  2    shows a signalling diagram illustrating a method of configuring the fronthaul communication link  30  connecting the REC A  10  and the RE A  20  according to an embodiment. 
     In step S 101   a , the REC A  10  is configured to be capable of receiving data over the fronthaul communication link  30  at a selected bitrate, for instance 10 Gbps, and with a selected communication protocol type, such as Ethernet. 
     At the other end of the fronthaul communication link  30 , the RE A  20  will correspondingly be configured to receive data in step S 102   a  at a selected bitrate and with a selected communication protocol type. In this example, the RE A  20  is configured to be capable of receiving the data at a bitrate of 25 Gbps over the fronthaul communication link  30  using CPRI. 
     Now, as is understood, it is not possible for the REC A  10  and the RE A  20  to exchange data over the link  30  utilizing different data bitrates and/or different communication protocols. If so, it is not possible for one device to correctly interpret the data transmitted by the other. In other words, data received at other bitrates and/or with other communication protocols than what any one of the REC A  10  and the RE A  20  has been configured to receive will not be decoded correctly. 
     Further, upon the configuration being performed in steps S 101   a -S 101   e  for the REC A  10  and in steps S 102   a -S 102   b  for the RE A  20 , at least one of the devices will transmit data over the fronthaul link  30  at the selected bitrate and protocol type. 
     In practice, both the REC A  10  and the RE A  20  will transmit data over the link  30  in case Ethernet is applied, while upon applying CRPI only the master device REC A  10  will transmit data initially until the slave device RE A  20  successfully has been able to decode the CPRI protocol at the selected bitrate, wherein the slave device RE A  20  also may start transmitting data over the link  30 . 
     The REC A  10  will thus transmit data in step S 101   a  over the fronthaul communication link  30  at the selected bitrate of 10 Gbps using Ethernet, while the RE A  20  is configured to be able to receive data in step S 102   a  over the fronthaul communication link  30  at the selected bitrate of 25 Gbps using CPRI. As mentioned, since the RE A  20  currently applies the CPRI protocol, the RE A  20  will yet not transmit data over the link  30 . 
     The REC A  10  will continuously detect whether or not the RE A  20  transmits data over the link at the same selected bitrate and with the same selected protocol for which the REC A has been configured to receive data over the link  30 , and vice versa, as illustrated with steps S 103  and S 104 . If so, the bitrate and the protocol will match, and the two devices  10 ,  20  may as a result successfully exchange data over the adequately configured link  30 . 
     However, in this particular exemplifying embodiment, after steps Sim and S 102   a  have been performed, there is no match, and the REC A  10  will adjust the bitrate and/or the protocol type for which it is configured to receive data. In this example, the REC A  10  is in step S 101   b  configured to receive Ethernet data at 25 Gbps, and as a result only the bitrate of the data transmitted over the fronthaul link  30  is adjusted to 25 Gbps in step S 101   b  while still transmitting the data over the link  30  in Ethernet format. 
     It should be noted that at this stage, it may be envisaged that the RE A  20  also adjusts the bitrate/protocol with which it is capable of receiving data, and thus also the bitrate of the data (and/or protocol type) transmitted over the link  30 , even though that is not performed in this particular example. 
     It is noted that adjustments of the bitrates may be undertaken every 0.9-1.1 s as specified in the CPRI specification 
     However, neither the REC A  10  nor the RE A  20  detects a match after the adjustment performed in step S 101   b , and the REC A  10  adjusts both the bitrate and the protocol type for the data it is configured to receive in step Slow to 10 Gbps and CPRI, while the RE A  20  adjusts the bitrate to 10 Gbps and the protocol to Ethernet in step S 102   b . In this example, the RE A  20  performs the adjustments every 3.9-4.1 s. Hence, the REC A  10  changes protocol to CPRI, and will send data over the link since the REC A  10  is the master device, and since the RE A  20  changes protocol to Ethernet, the RE A  20  will start transmitting data at 10 Gbps. 
     Again, it can be concluded that no match is detected, whereupon the REC A  10  adjusts the bitrate to 25 Gbps while maintaining the CPRI protocol in step S 101   d , but still no match is detected. 
     Finally in step S 101   e , the REC A 10  adjusts the bitrate to 10 Gbps and the protocol type to Ethernet, which indeed matches the bitrate and the protocol for the data transmitted by the RE A  10  over the fronthaul communication link  30  as adjusted by the RE A 10  in step S 102   b . As a result, a match is detected by the REC A  10  in step S 103  and by the RE A  20  in step S 104 , and it is now possible for the REC A  10  and the RE A  20  to exchange information over the fronthaul link  30 . 
     In step S 105  and S 106 , respectively, the REC A  10  and the RE A  20  both select the matching bitrate (10 Gbps) and protocol type (Ethernet) for the data transmitted over the fronthaul link  30 , and the link is thus adequately configured in that data successfully can be exchanged between the REC A  10  and the RE A  20  over the link  30  using the selected matching bitrate of 10 Gbps and the selected matching communication protocol type being Ethernet. 
     Thus, when the REC A 10  adjusts the bitrate of the data transferred over the link  30  to 10 Gbps and the protocol type to Ethernet in step S 101   e , there is match in that both the REC A  10  and the RE A  20  now is configured to be capable of receiving data over the link  30  at the same bitrate of 10 Gbps using Ethernet, while transmitting data over the link  30  at the same bitrate and with the same communication protocol. 
     Finally, from the detection performed by the REC A  10  in step S 103  (where a corresponding detection thus is performed at the other end of the link  30  by the RE A  20  in step S 104 ), the matching bitrate—i.e. the bitrate supported by both the REC A  10  and the RE A  20 —and the protocol type utilized by the two devices are selected as the bitrate and protocol type used for transmitting and receiving data over the established fronthaul communication link  30  in steps S 105  and S 106 . 
     Advantageously, with the embodiment of  FIG.  2   , a process is provided where the established fronthaul communication link  30  is adequately configured such that data may be exchanged by the RE A  10  and the REC A  20  over the fronthaul communication link  30 . 
     In the art, for instance when establishing an optical fronthaul link using Ethernet, the REC A  10  and the RE A  20  (and thus the link  30 ) must be configured before the two devices are connected to each other by the fronthaul communication link  30 —for instance during manufacturing. The bitrate and communication protocol is more or less hardcoded into the REC A  10  and the RE A  20  such that the two devices are capable of communicating with each other once being connected to by means of a fronthaul communication link. Such configuration process is highly inefficient, and further cannot be adjusted on-the-fly. 
     Further it may be envisaged that Forward Error Correction (FEC) methods used by the REC A  10  and RE A  20  must match for the fronthaul link  30  to be correctly configured. For instance, if the REC A  10  applies RS-FEC, then the RE A  20  must also apply RS-FEC. Thus, different FEC method may have to be applied by the two devices throughout steps S 101   a -S 101   e  and S 102   a - 102   b , respectively, until a match occurs. 
     In a further embodiment with reference to the signalling diagram of  FIG.  3   , a confirmation procedure may be undertaken where after having detected that the bitrate and communication protocol for which the REC A  10  is configured to receive data is equal to the bitrate and protocol of the data received from the RE A  20 , the REC A  10  informs the RE A  20  in step S 107  of the selected (matching) bitrate of 10 Gbps and that the selected protocol is Ethernet may be used when communicating over the fronthaul link  30 , and the RE A  20  informs the REC A  10  accordingly in step S 108 . Optionally, the type of FEC for which there is a match is included in the information exchanged in steps S 107  and S 108 . 
     The information message of step S 107  and the confirmation message of step S 108  are typically sent using a protocol that only enables sending of data across the link  30  and not routeing the message across other potential links in multiple hops. Such a protocol may be so-called Slow Protocol or Link Layer Discovery Protocol (LLDP) in the Ethernet case. 
     It may further be envisaged that the REC A  10  sends information to the RE A  20  in step S 107  regarding all its capabilities in terms of bitrate and protocol (and FEC type). In this example, the REC A  10  may send information indicating that it is (at least) capable of receiving and transmitting data at both 10 Gbps and 25 Gbps using Ethernet and at both 10 Gbps and 25 Gbps using CPRI. 
     Correspondingly, the RE A  20  will send information in step S 108  indicating that it is (at least) capable of receiving and transmitting data at both  10  Gbps and 25 Gbps using CPRI and at 10 Gbps using Ethernet. 
     In step S 109 , if it is envisaged that a number of matching bitrates and protocols are found from the information exchanged in steps S 107  and S 108  (but which were not tried in previous steps S 101   a -S 104 ), the REC A  10  determines in step S 109  which combination of the numerous matching bitrates and protocols to select for configuring the fronthaul link  30 . 
     For instance, it may be envisaged that 1) a highest matching bitrate is utilized, 2) a highest matching bitrate for a particular protocol, 3) a highest bitrate for a particular matching FEC, or just 4) a preferred protocol type regardless of bitrate, etc. Any matching combination is possible, even though it is likely in practice that a highest possible bitrate is used for communication over the fronthaul link  30 . 
     For instance, in the example of  FIG.  2  and  3   , one matching combination is illustrated to be detected at a bitrate of 10 Gbps utilizing Ethernet. However, if further matching combinations were found in the information exchanged in steps S 107  and S 108 , e.g. 25 Gbps while using CPRI, then that combination is typically more preferred for configuration of the fronthaul link  30  than using Ethernet at 10 Gbps. 
     The selected matching combination of data bitrate-protocol type is communicated to the RE A  20  in step S 110 , which responds with a confirmation in step S 111 . 
     It should be noted that steps S 105 -S 111  may be performed in a different order where the RE A  20  controls the selection of a matching bitrate-protocol combination instead of the REC A  10 , and the REC A  10  is hence the more passive of the two. 
     In step S 112 , the fronthaul link  30  is configured by REC A using the determined bitrate and communication protocol (and possibly FEC type) for the data communicated over the link  30 . If this is the same bitrate as configured in steps Sins and step S 106 , the fronthaul link  30  remains unchanged. 
     However, as mentioned, if one or more further matching combinations have been found from the information exchanged in step S 107  and S 108 , where a higher matching bitrate of e.g. 25 Gbps using CPRI has been found, then 25 Gbps will be selected by the REC A  10  in step S 112  as the bitrate utilized when communicating data over the link  30  (using CPRI), and the same procedure is performed by the RE A  20  in step S 113 . 
     Advantageously, the fronthaul communication link  30  is now configured and operational using the best possible settings given the capabilities of both REC A and RE A  20  as determined by the REC A  10  in step S 109 . 
     In steps S 114  and S 115 , the REC A  10  and the RE A  20 , respectively, proceeds with communication using the standard protocol stack with transport, network and session protocols, for example transmission control protocol (TCP) and High-Level Data Link Control (HDLC). 
     If the protocol stack would have been established on the REC A  10  and the RE A  20 , respectively, in steps S 105  and Sio 6  and any capability information would have been exchanged using the standard protocol stack, the change of bitrate and protocol type—in this example from 10 Gbps Ethernet to 25 Gbps CPRI—would have to be performed with the protocol stack operational. This interruption in traffic may be discovered by many software stacks in the system and be falsely reported as a fault. It would also take more time to establish and then re-establish the protocol stack than to establish it only once. Typically, higher layer protocol stacks are established end-to-end from NMS (Network Management System) to each RE. 
     Advantageously, with the fronthaul link configuration method according to the described embodiments, it is ensured that preferred link configuration—such as highest possible bitrate for a given protocol such as for instance CPRI or Ethernet—is selected without requiring that each link is explicitly configured by a network operator. This advantageously makes the system easier to configure and upgrade, and may save the operator site visits. 
       FIG.  4    shows the REC A  10  and the RE A  20  being connected to an intermediate unit  40 , being for instance a CPRI switch, an Ethernet Switch, or a combined CPRI/Ethernet Switch via a first fronthaul link  30   a  and a second fronthaul link  30   b , respectively. 
       FIG.  5    shows a signalling diagram illustrating a method of configuring the respective fronthaul communication link  30   a  and  30   b  connecting the REC A  10  and the RE A  20  to the intermediate unit  40  according to an embodiment. 
     The intermediate unit  40  is in this embodiment a radio equipment device which is only capable of transmitting and receiving data at a specific bitrate using a specific communication protocol, in this example the intermediate unit  40  communicates at 25 Gbps using Ethernet. 
     As in the embodiments of  FIGS.  2  and  3   , in step Sioia, the REC A  10  is configured to be capable of receiving data over the first fronthaul communication link  30   a  at a selected bitrate, for instance 10 Gbps, and with a selected communication protocol type, such as Ethernet. The REC A  10  will also transmit data over the first link  30   a  using the selected bitrate and protocol. 
     For the second fronthaul communication link  30   b , the RE A  20  will correspondingly be configured to be capable to receive data in step S 102   a  at a selected bitrate and with a selected communication protocol type and transmit data using the selected parameters. In this example, the RE A  20  transmits the data at a bitrate of 10 Gbps over the second fronthaul communication link  30   b  using Ethernet. 
     Now, in line with previous discussions, it is not possible for the REC A  10  and the RE A  20  to exchange data over the first link  30   a  and the second link  30   b , respectively, via the intermediate unit  40  utilizing different data bitrates and/or different communication protocols. If so, it is not possible for one device to correctly interpret the data transmitted by the other, since the bitrate and the protocol type of both REC A  10  and the RE A must be adjusted to match the bitrate and the protocol type used for communication by the intermediate unit  40 . 
     In this particular exemplifying embodiment, after steps S 101   a  and S 102   a  have been performed, there is no match, and the REC A  10  will adjust the bitrate and/or the protocol type for the data it is configured to receive. In this example, only the bitrate of the data communicated over the first fronthaul link  30   a  is adjusted (to 25 Gbps) in step S 101   b  while still communicating the data over the first link  30   a  in Ethernet format. 
     As can be concluded, this is a match for the data communication over the first fronthaul link  30   a  between the REC A  10  and the intermediate unit  40 . Similarly, the RE A  20  finds a match with the intermediate unit  40  correspondingly in step S 102   b  over the second link  30   b.    
     In step S 105  and S 106 , respectively, the REC A  10  and the RE A  20  both select the matching bitrate (25 Gbps) and protocol type (Ethernet) for the data communicated with the intermediate unit  40  over the respective fronthaul link  30   a  and  30   b , and the links are thus adequately configured in that data successfully can be exchanged between the REC A  10  and the RE A  20  via the intermediate unit  40  over the links  30   a  and  30   b  using the selected matching bitrate of 25 Gbps and the selected matching communication protocol type being Ethernet. 
     In line with previous discussions, the REC A  10  informs the intermediate unit  40  in step S 107  of the selected (matching) bitrate of 25 Gbps and that the selected protocol is Ethernet when communicating over the fronthaul link  30  using e.g. Slow Protocol or LLDP, and the REC A  10  possibly also informs the intermediate unit  40  about its capabilities in terms of bitrates and protocol types. 
     However, since the intermediate unit  40  is not capable of communicating according to embodiments described herein, the intermediate unit  40  cannot respond with informing the REC A  10  (as was previously performed by the RE A  20  in step S 108 ). 
     The REC A  10  will conclude in step S 112   a  that a set response timer performs a time-out and that the configuration performed in step S 105  for the first fronthaul link  30   a  is to be maintained. Correspondingly, the RE A  20  will conclude in step S 113   a  that a capabilities message was not received in reply to the information sent in step S 108  and that a set request timer accordingly performs a time-out, and that the configuration performed in step S 106  for the second fronthaul link  30   b  is to be maintained. 
     Finally, the REC A  10  and the RE A  20  proceed with establishing their protocol stacks in step S 114  and S 115 , respectively, as previously described. 
     Advantageously, with this embodiment, the fronthaul communication links  30   a  and  30   b  are configured even though an intermediate unit  40  not supporting the configuration process of adjusting bitrate and/or protocol type is connected to the first link  30   a  and the second link  30   b.    
       FIG.  6    illustrates a radio equipment device, in this exemplifying embodiment the REC A  10 , arranged to configure a fronthaul communication link established with another radio equipment device according to an embodiment. The steps of the method performed by the REC A  10  are in practice performed by a processing unit  11  embodied in the form of one or more microprocessors arranged to execute a computer program  12  downloaded to a suitable storage volatile medium  13  associated with the microprocessor, such as a Random Access Memory (RAM), or a non-volatile storage medium such as a Flash memory or a hard disk drive. The processing unit  11  is arranged to cause the REC A  10  to carry out the method according to embodiments when the appropriate computer program  12  comprising computer-executable instructions is downloaded to the storage medium  13  and executed by the processing unit ii. The storage medium  13  may also be a computer program product comprising the computer program  12 . Alternatively, the computer program  12  may be transferred to the storage medium  13  by means of a suitable computer program product, such as a Digital Versatile Disc (DVD) or a memory stick. As a further alternative, the computer program  12  may be downloaded to the storage medium  13  over a network. The processing unit  11  may alternatively be embodied in the form of a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field-programmable gate array (FPGA), a complex programmable logic device (CPLD), etc 
     The aspects of the present disclosure have mainly been described above with reference to a few embodiments and examples thereof. However, as is readily appreciated by a person skilled in the art, other embodiments than the ones disclosed above are equally possible within the scope of the invention, as defined by the appended patent claims. 
     Thus, while various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.