Embodiments herein relate generally to a Radio Access Network (RAN) node and a method in the radio access network node. More particularly the embodiments herein relate to transmitting location information associated with a User Equipment (UE) to a first Core Network (CN) node in a communications network.
In a typical cellular network, also referred to as a wireless communication system, user equipment's, communicate via the radio access network to one or more core networks.
A user equipment is a device by which a subscriber may access services offered by an operator's core network and services outside the operator's network to which the operator's radio access network and core network provide access, e.g. access to the Internet. The user equipment may be any device, mobile or stationary, enabled to communicate over a radio channel in the communications network, for instance but not limited to e.g. mobile phone, smart phone, sensors, meters, vehicles, household appliances, medical appliances, media players, cameras, or any type of consumer electronic, for instance but not limited to television, radio, lighting arrangements, tablet computer, laptop, or PC. The user equipment may be portable, pocket-storable, hand-held, computer-comprised, or vehicle-mounted mobile devices, enabled to communicate voice and/or data, via the radio access network, with the core network.
The radio access network covers a geographical area which is divided into cell areas, with each cell area being served by a base station, e.g. a Radio Base Station (RBS), which in some radio access networks is also called eNodeB (eNB), NodeB, B node or base station. A cell is a geographical area where radio coverage is provided by the base station at a base station site. The base stations communicate over the air interface operating on radio frequencies with the user equipment's within range of the base stations.
The location based service becomes the top ranked service in these years, for example, mobile maps, emergency call positioning, local search, advertising, self-location, location based charging, etc. With those increasing market demanding, the user equipment's location information becomes more and more interesting and attractive to the operators. The accurate and timely location report from the radio access network, the core network to an Online Charging System (OCS) and a Policy and Charging Rules Function (PCRF), is highly wanted by the operators. The OCS is a system or a node allowing a communications service provider to charge their customers, in real time, based on service usage. The PCRF is a node, operating in the core network, that encompasses policy control decision and flow based charging control functionalities.
Currently in the Third Generation Partnership Project (3GPP), there are two kinds of location reporting procedures defined for the location service:
Preparation stage: From Steps 101˜106, the OCS/PCRF orders the location change reporting for a user equipment during this user equipment's mobility or session procedures, for example attach, Packet Data Protocol (PDP) context activation, etc. The OCS and the PCRF are two separate nodes.
Execution stage, from steps 100a˜100c, the radio access network node reports the changed location information to OCS/PCRF once this user equipment's location is changed. The location may be a Cell Global Identity (CGI) in a Global System for Mobile Communication (GSM) network, a Service Area Identifier (SAI) in a Wideband Code Division Multiple Access (WCDMA) network, or E-UTRAN Cell Global Identifier/Tracking Area Identity (ECGI/TAI) in a Long Term Evolution (LTE) network. E-UTRAN is the abbreviation for Evolved Universal Terrestrial Radio Access Network. The radio access network node is referred to as a RAN node in some of the drawings.
According to the 3GPP, the CGI is the concatenation of the Location Area Identification (LAI) and the Cell Identity (CI). The base station system and the cell within the base station system are identified within a location area or routing area by adding the cell identity to the location area identification or the routing area identification.
SAI is defined by the 3GPP to be used to identify an area comprising one or more cells belonging to the same Location Area. Such an area is called a Service Area and may be used for indicating the location of a user equipment to the core network.
In an LTE network, the ECGI is a concatenation of a PLMN Identifier (PLMN-ID) and the E-UTRAN Cell Identity (ECI). The TAI is used to identify a Tracking Area (TA). A tracking area is a Tracking a logical grouping of cells in a LTE network.
When the OCS/PCRF receives the user equipment location information, the OCS/PCRF starts the location based charging or policy control, for example, initiates the Quality of Service (QoS) modification.
The procedure in
The OCS/PCRF sends a Location Report Start Request to the GGSN/SGW/PGW. Which of the nodes GGSN, SGW or PGW the request is sent to is dependent on whether the communications network is a GSM network, a WCDMA network or a LTE network. In a GSM or a WCDMA network, the Location Report Start Request is sent to the GGSN. In a GSM or WCDMA or LTE, the Location Report Start Request is sent to the SGW/PGW. The Location Report Start Request comprises a user equipment ID. The user equipment ID may also be referred to as subscriber ID. The user equipment ID may be an International Mobile Subscriber Identity (IMSI), Mobile Station International Subscriber Directory Number (MSISDN), International Mobile Equipment Identity (IMEI), etc. In some embodiments, the GGSN, SGW and the PGW are three separate nodes or they may be co-located in one node. The location Report Start request may be for example a CCA Initial message or a CCA Update message. CCA is short for Credit Control Answer.
GGSN is short for Gateway GPRS Support Node and is a core network node acting as a gateway between the GPRS network and an external Packet Data Network (PDN). The GGSN provides network access to external hosts wishing to communicate with the user equipment. GPRS is short for General Packet Radio Service.
SGW is short for Serving GateWay and is a gateway in the core network which routes and forwards user data packets. The SGW also acts as a mobility anchor during inter-eNB handovers and as a mobility anchor for mobility between LTE and other 3GPP technologies.
PGW is short for PDN GateWay and is a gateway that provides connectivity from the user equipment to an external PDN. The PGW is the point of exit and entry for data traffic for the user equipment. The user equipment may have simultaneous connectivity with more than one PGW for accessing multiple PDNs. Another function of the PGW is to act as the anchor for mobility between 3GPP and non-3GPP technologies.
Upon receipt of the Location Report Start Request, the GGSN/SGW/PGW sends a Location Report Start Response back to the OCS/PCRF confirming that it has received the Location Report Start Request.
The GGSN/SGW/PGW forwards the Location Report Start Request comprising the user equipment ID to the SGSN-MME. SGSN is short for Serving GPRS Support Node and is a main component of the GPRS core network. The SGSN handles all packet switched data within the network, e.g. the mobility management and authentication of the user equipment. The MME is short for Mobility Management Entity and is a core network node responsible for mobility in the core network. The SGSN and the MME is co-located in one node.
Upon receipt of the Location Report Start Request, the SGSN-MME sends a Location Report Start Response back to the GGSN/SGW/PGW.
The SGSN-MME forwards the Location Report Start Request comprising the user equipment ID to the radio access network node.
Upon receipt of the Location Report Start Request, the radio access network node sends a Location Report Start Response back to the SGSN-MME. With this step, the preparation stage where the OCS/PCRF asks for Location Reporting per user equipment is finished.
After the preparation stage in steps 101-106 has been completed, the execution stage starts which involves reporting of the user equipment location once the location has changed, i.e. the user equipment is moving. Step 100a may start directly after step 106 or it may start a time period after step 106.
The radio access network node is referred to as a RAN node in some of the drawings sends a Location User Equipment Report to the SGSN-MME when the location of the user equipment has changed. The Location User Equipment Report comprises a user equipment ID and the Location Information. The Location User Equipment Report may also be referred to as a Location Subscriber Report.
The SGSN-MME forwards the Location User Equipment Report comprising the user equipment ID and the Location Information to the GGSN/SGW/PGW.
The GGSN/SGW/PGW forwards the Location User Equipment Report comprising the user equipment ID and the Location Information to the OCS/PCRF. This completes the first part of the execution stage.
The second part of the execution stage takes place directly or a time after step 100c has been completed. In the second part, the OCS/PCRF triggers the GGSN/SGW/PGW to initiate the PDP Context/Evolved Packet System (EPS) bearer modification to update the QoS, for this user equipment.
There are mainly two problems in these existing solutions:
The first problem is that both of the above two solutions 1 and 2 are based on the signaling procedures. These signaling procedures for location reporting will overload the network more or less.
The second problem is that only a limited number of user equipment's may be served with the location based service. The OCS and the PCRF may only deploy the different charging or policy control for some pre-defined user equipment's based on their location information. The number of these pre-defined user equipment's will not be too high. If the number of pre-defined user equipment's is too high, the signaling for the location reporting for these user equipment's will overload the radio access network, the core network, the OCS and the PCRF.
The Pros and Cons of the existing solutions are listed in the below table 1:
A disadvantage of the existing solutions is that they require a large amount of signaling between the radio access network, the core network and the PCRF/OCS.
In order to achieve the location reporting from end to end, a large amount of control-plane signaling must be supported from end to end, for example, lu-C, S1-MME, GTPv1, GTPv2. lu-C is the interface that connects the Radio Network Controller (RNC) to the SGSN. MME is the interface between the MME and the eNB. GTP is short for GPRS Tunneling Protocol.
With the existing location reporting procedures, another disadvantage is that only a limited amount of user equipment's may enjoy the service of location reporting.
Another disadvantage is that the location reporting is inefficient and the implementation costs for the radio access network and the core network is high. Another disadvantage is that the location reporting stops cannot be decreased.
An objective of embodiments herein is therefore to obviate at least one of the above disadvantages and to provide improved location reporting in the communications network.
According to a first aspect, the object is achieved by a method in a radio access network node for transmitting location information associated with a user equipment to a first core network node in a communications network. The radio access network node transmits the location information to the first core network node using a General packet radio service Tunneling Protocol-User plane, GTP-U, protocol. The location information is enclosed in a GTP-U header of payload data traffic.
According to a second aspect, the object is achieved by a radio access network node for transmitting location information associated with a user equipment to a first core network node in a communications network. The radio access network node comprises a transmitter which is configured to transmit the location information to the first core network node using the GTP-U protocol. The location information is enclosed in a GTP-U header of payload data traffic.
Since the location information is enclosed in the payload data traffic and sent from the radio access network node to the first core network node using the GTP-U protocol, the location reporting in the communications network is improved.
Embodiments herein afford many advantages, of which a non-exhaustive list of examples follows:
An advantage of the embodiments herein is that they will decrease the signaling for the location reporting from end to end, i.e. between the radio access network node, the first core network node and the PCRF/OCS. It will help the operators to have more and more attractive location based services put into use.
Another advantage is that a larger number of user equipment's may enjoy the service.
With the embodiments herein, an advantage is that the location reporting is efficient and in real-time.
Another advantage is that only the GTP-U based payload data traffic is impacted by the embodiments herein and that is only necessary to add some new octets into the GTP-U header of each payload data packet.
Another advantage of the embodiments herein is that their implementation cost for the radio access network and the, core network is low.
Another advantage is that the location reporting stops can be decreased (in case of 3GDT and LTE access network.)
The embodiments herein are not limited to the features and advantages mentioned above. A person skilled in the art will recognize additional features and advantages upon reading the following detailed description.
The embodiments herein will now be further described in more detail in the following detailed description by reference to the appended drawings illustrating the embodiments and in which:
The drawings are not necessarily to scale and the dimensions of certain features may have been exaggerated for the sake of clarity. Emphasis is instead placed upon illustrating the principle of the embodiments herein.
The embodiments herein relate to transfer the user equipment's location information between the radio access network and the core network by using the payload data traffic, through the extension header in each GTP-U packets.
The wireless communications network 200 comprises a user equipment 201 present within a cell and served by a radio access network node 202, and is in this case capable of communicating with the radio access network node 202 over a radio carrier. The radio access network node 202 may be a Base Station Controller (BSC), a Radio Network Controller (RNC), a base station such as an eNB, or any other network unit capable to communicate over a radio carrier with the user equipment 201. The radio access network node 202 is comprised in the radio access network 200a. The radio access network node will be referred to as a RAN node in some of the figures.
The user equipment 201 may be any device, mobile or stationary, enabled to communicate over the radio channel in the communications network, for instance but not limited to e.g. mobile phone, smart phone, sensors, meters, vehicles, household appliances, medical appliances, media players, cameras, or any type of consumer electronic, for instance but not limited to television, radio, lighting arrangements, tablet computer, laptop, or PC. The user equipment 201 is referred to as UE in some of the figures.
The radio access network 200a and the radio access network node 202 are connected to the core network 200b. In some embodiments, the radio access network node 202 is connected to a first core network node 203 in the core network 200b. The first core network node 203 may be a GGSN, a SGW or a PGW.
In some embodiments, the radio access network node 202 is connected to the first core network node 203 via a second core network node 204. The second core network node 204 may be a SGSN.
The first core network node 203 is connected to an OCS/PCRF 205, i.e. the first core network node 203 is connected to an OCS or a PCRF. The OCS/PCRF 205 is also comprised in the core network 200b. When the first core network node 203 is a GGSN, the GGSN is connected to the OCS via the Gy interface. At the same time, the GGSN may be connected to the PCRF via the Gx interface.
When the communications network 200 is a GSM network, the radio access network node 202 is a GERAN node such as the BSC, the first core network node 203 is a GGSN or a SGW/PGW and the second core network node 204 is a SGSN-MME. MME is for LTE access, and SGSN is for GSM and WCDMA.
When the communications network 200 is a WCDMA network, the radio access network node 202 is a UTRAN node such as the RNC, the first core network node 203 is a GGSN or a SGW/PGW and the second core network node 204 is a SGSN.
When the communications network 200 is a LTE network, the radio access network node 202 is an E-UTRAN node such as the eNB, the first core network node 203 is a SGW/PGW.
The payload based location reporting procedure for transmitting location information associated with the user equipment 201 to the first core network node 203 in the communications network 200 according to some embodiments will now be described with reference to the combined signaling diagram and flowchart depicted in
Step 301 initiates the preparation stage by the OCS/PCRF 205 sending a Location Report Start Request to the first core network node 203, e.g. GGSN/SGW/PGW. Which of the nodes GGSN, SGW or PGW the request is sent to is dependent on whether the communications network is a GSM network, a WCDMA network or a LTE network. The Location Report Start Request comprises a user equipment ID.
Upon receipt of the Location Report Start Request, the first core network node 203, e.g. GGSN/SGW/PGW, sends a Location Report Start Response back to the OCS/PCRF 205 confirming that it has received the Location Report Start Request.
The first core network node 203, e.g. GGSN/SGW/PGW, forwards the Location Report Start Request comprising the user equipment ID to the second core network node 204, e.g. SGSN-MME.
Upon receipt of the Location Report Start Request, the second core network node 204, e.g. SGSN-MME, sends a Location Report Start Response back to the first core network node 203, e.g. GGSN/SGW/PGW.
The second core network node 204, e.g. SGSN-MME forwards the Location Report Start Request comprising the user equipment ID to the radio access network node 202.
Upon receipt of the Location Report Start Request, the radio access network node 202 sends a Location Report Start Response back to the second core network node 204, e.g. SGSN-MME. With this step 306, the preparation stage where the OCS/PCRF 205 asks for Location Reporting per user equipment is finished.
After the preparation stage in steps 301-306 has been completed, the execution stage starts which involves reporting of the user equipment location once the location has changed, i.e. the user equipment 201 is moving. Step 300a may start directly after step 306 or it may start a time period after step 306.
The radio access network node 202 reports the changed location information to the second core network node 204, e.g. SGSN, by the payload data traffic using the GTP-U protocol or using UL-UNIDATA. The location information may be a CGI (GSM), SAI (WCDMA), or ECGI/TAI (LTE). The changed location information is enclosed in GTP-U header of the payload data traffic.
Payload data traffic, also referred to as the actual or body data, is the cargo of a data transmission. It is the part of the transmitted data which is the fundamental purpose of the transmission. The payload does not include the “overhead” data required to get the packet to its destination such as e.g. headers. The payload data traffic comprises, in addition to the location information, for example voice data, video data etc.
GTP is a group of IP-based communications protocols used to carry GPRS within GSM, UMTS and LTE networks. GTP may be decomposed into separate protocols: GTP-C, GTP-U and GTP′. GTP-C is used within the GPRS core network for signaling between the GGSN and the SGSN. GTP-U is used for carrying encapsulated payload data traffic and signaling messages within the GPRS core network and between the radio access network and the core network. For GTP-U protocol, it is GTPv1-U. Different GTP variants are implemented by RNCs, SGSNs, GGSNs, SGWs, PGWs within 3GPP networks.
The location information indicated by User Location Information (ULI) is to be included into GTP-U header. The ULI is a variable length Information Element (IE) and it is coded as shown in
In octet 1, bit 4 comprises a spare bit. It shall be set to “0”, and the receiver shall not evaluate this bit. In octet 1, bit 5 comprises information about the Protocol Type (PT) and is a bit used to differentiate between GTP (when PT is “1”) and GTP′ (when PT is “0”). Octet 1, bits 6-8, comprises a version field which is used to determine the version of the GTP-U protocol. The version number shall be set to ‘1’.
Octet 2 comprises the message type, i.e. it indicates the type of GTP-U message.
Octet 3 and octet 4 comprise information about the length in octets of the payload data traffic, i.e. the rest of the packet following the mandatory part of the GTP-U header (that is the first 8 octets). Octet 3 is represents the length of the first octet and octet 4 represents the length of the second octet.
Octets 5-8 in
Returning to
The second core network node 204, e.g. the SGSN, reports the changed location information to the first core network node 203, e.g. SGW/PGW, by the GTP-U header of payload data traffic using the GTP-U protocol. The GTP-U protocol may be the GTPv1-U protocol. The changed location information is enclosed in GTP-U header of the payload data traffic.
Step 300ab is performed instead of steps 300a and 300b. If 3GDT is used in a WCDMA network, the radio access network node 202 reports the changed location information to the first core network node 203, e.g. the GGSN/SGW, directly using the GTP-U protocol. 3GDT is a 3G Direct Tunnel allows data traffic to bypass the second core network node 204, i.e. the SGSN-MME, which significantly increases the throughput capacity in the core network. The changed location information is enclosed in GTP-U header of the payload data traffic.
The first core network node 203, e.g. the GGSN or the SGW/PGW reports the changed location information to the OCS/PCRF 205 once this user equipment's location is changed. The changed location information is enclosed in GTP-U header of the payload data traffic. This completes the first part of the execution stage.
The second part of the execution stage takes place directly or a time after step 300c has been completed. The OCS/PCRF 205 receives the user equipment location information from the first core network node 203 and the OCS/PCRF 205 starts the location based charging or policy control, for example, initiates the QoS modification.
The method will now be described for when the communications network 200 is a GSM network, a WCDMA network and a LTE network.
The physical layer is illustrated by the GSM Radio Frequency (GSM RF) for the user equipment 201, the GSM RF and L1bis for the GERAN 202, L1bis and L1 for the SGSN 204 and L1 for the GGSN 203 in
In
The network layer is illustrated by the SNDCP for the user equipment 201, the SNDCP and the GTP-U for the SGSN 204 and the GTP-U for the GGSN 203. The SNDCP is short for Sub Network Dependent Convergence Protocol and it is used to transfer data packets between the SGSN 204 and the user equipment 201. As seen in
On top of the protocol stack is the IP and the application layer. The relay represents the payload data traffic between the different nodes.
In
The physical layer is illustrated by the GSM RF for the user equipment 201, the GSM RF and L1bis for the GERAN 202, L1bis and L1 for the SGSN 204 and L1 for the SGW/PGW 203 in
In
The network layer is illustrated by the SNDCP for the user equipment 201, the SNDCP and the GTP-U for the SGSN 204 and the GTP-U for the SGW/PGW 203. The SNDCP is used to transfer data packets between the SGSN 204 and the user equipment 201. As seen in
On top of the protocol stack is the IP and the application layer. The relay represents the payload data traffic between the different nodes.
In
The physical layer is illustrated by the L1 for the user equipment 201, the UTRAN 202, the SGSN 204 and for the GGSN 203 in
In
The network layer is illustrated by the PDCP for the user equipment 201, the PDCP and the GTP-U for the UTRAN, GTP-U for the SGSN 204 and for the GGSN 203. As seen in
On top of the protocol stack is the IP, PPP and the application layer. The relay represents the payload data traffic between the different nodes.
In
The physical layer is illustrated by the L1 for the user equipment 201, the UTRAN 202 and for the GGSN 203 in
In
The network layer is illustrated by the PDCP for the user equipment 201, the PDCP and the GTP-U for the UTRAN and GTP-U for the GGSN 203. As seen in
On top of the protocol stack is the IP, PPP and the application layer. The relay represents the payload data traffic between the different nodes.
In
The physical layer is illustrated by the L1 for the user equipment 201, the UTRAN 202, the SGSN 204 and for the SGW/PGW 203 in
In
The network layer is illustrated by the PDCP for the user equipment 201, the PDCP and the GTP-U for the UTRAN and GTP-U for the SGSN 204 and the SGW/PGW 203. As seen in
On top of the protocol stack is the IP, PPP and the application layer. The relay represents the payload data traffic between the different nodes.
In
The physical layer is illustrated by the L1 for the user equipment 201, the UTRAN 202, the and for the SGW/PGW 203 in
In
The network layer is illustrated by the PDCP for the user equipment 201, the PDCP and the GTP-U for the UTRAN and GTP-U for the SGW/PGW 203. As seen in
On top of the protocol stack is the IP, PPP and the application layer. The relay represents the payload data traffic between the different nodes.
In
The physical layer is illustrated by the L1 for the user equipment 201, the E-UTRAN 202 and for the SGW/PGW 203 in
In
The network layer is illustrated by the PDCP for the user equipment 201, the PDCP and the GTP-U for the E-UTRAN 202 and GTP-U for the SGW/PGW 203. As seen in
On top of the protocol stack is the IP and the application layer. The relay represents the payload data traffic between the different nodes.
In
The method described above will now be described seen from the perspective of the radio access network node 202.
This step corresponds to steps 300a, 300b, and 300ab in
The radio access network node 202 transmits the location information to the first core network node 203 using the GTP-U protocol. The location information is enclosed in the GTP-U header of payload data traffic. The GTP-U protocol may be the GTPv1-U protocol. The location information is real-time information about the location of the user equipment 201. The location information may be a first location or a changed location. Real-time information is associated with something that occurs immediately, i.e. when the user equipment 201 changes location the location information about the changed location is transmitted immediately from the radio network node 202 to the first core network node 203.
In some embodiments, the location information is transmitted directly to the first core network node 203 or the location information is transmitted to the first core network node 203 via the second core network node 204.
In some embodiments, the payload data traffic is transmitted using the GTP-U protocol and using the UL-UNIDATA. The GTP-U protocol may be the GTPv1-U protocol. The changed location information is enclosed in GTP-U header of the payload data traffic.
In some embodiments, the location information is a CGI, a SAI, a, ECGI or a TAI.
In some embodiments, the location information is transmitted directly to the first core network node 203 using a Third Generation Direct Tunnel, 3GDT.
In some embodiments, the radio access network node 202 is represented by a BSC, a RNC or an eNB.
In some embodiments, the first core network node 203 is represented by a GGSN, a SGW or a PGW.
In some embodiments, the second core network node 204 is represented by a SGSN.
In some embodiments, the communications network 200 is based on GSM, WCDMA or LTE.
To perform the method steps shown in
The radio access network node 202 comprises a transmitter 1401 configured to transmit the location information to the first core network node 203 using the GTP-U protocol. The location information is enclosed in payload data traffic. The location information is enclosed in GTP-U header of the payload data traffic. The transmitter 1401 may be further configured to transmit the location information directly to the first core network node or to transmit the location information to the first core network node via a second core network node. In some embodiments, the transmitter 1401 is further configured to transmit the payload data traffic using the GTP-U protocol or using the GTP-U protocol and the UL-UNIDATA. The GTP-U protocol may be the GTPv1-U protocol. In some embodiments, the location information is a CGI, a SAI, an ECGI or a TAI. In some embodiments, the transmitter 1401 is further configured to transmit the location information directly to the first core network node 203 using a 3GDT. In some embodiments, the second core network node 204 is represented by a SGSN.
The radio access network node 202 may further comprise a receiver 1403 configured to receive a Location Report Start Request from the first core network node 203 and/or from the second core network node 204. The receiver 1403 may also be configured to receive information from the user equipment 201 about a changed location.
The radio access network node 202 may further comprise a memory 1405 comprising one or more memory units. The memory 1405 is arranged to be used to store data, received data streams, threshold values, time periods, configurations, scheduling's, and applications to perform the methods herein when being executed in the radio access network node 202.
The present mechanism for transmitting location information associated with a user equipment 201 to a first core network node 203 in a communications network 200 may be implemented through one or more processors, such as a processor 1407 in the user equipment arrangement depicted in
Those skilled in the art will also appreciate that the transmitter 1401 and the receiver 1403 described above may refer to a combination of analog and digital circuits, and/or one or more processors configured with software and/or firmware, e.g. stored in a memory, that when executed by the one or more processors such as the processor 1407 perform as described above. One or more of these processors, as well as the other digital hardware, may be included in a single application-specific integrated circuit (ASIC), or several processors and various digital hardware may be distributed among several separate components, whether individually packaged or assembled into a system-on-a-chip (SoC).
The embodiments herein are not limited to the above described embodiments. Various alternatives, modifications and equivalents may be used. Therefore, the above embodiments should not be taken as limiting the scope of the embodiments, which is defined by the appending claims.
It should be emphasized that the term “comprises/comprising” when used in this specification is taken to specify the presence of stated features, integers, steps or components, but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof. It should also be noted that the words “a” or “an” preceding an element do not exclude the presence of a plurality of such elements.
It should also be emphasized that the steps of the methods defined in the appended claims may, without departing from the embodiments herein, be performed in another order than the order in which they appear in the claims.