Abstract:
The amount of data that is transmitted over a cellular network is reduced thereby providing an improvement in the quality of service. The data reduction is obtained by intercepting data units transferred over a bearer between two nodes, such as a BTS and BSC. The current load for a bearer is determined and based on the current load, the source of the data is requested to change the bit rate of subsequent data units. Thus, the bit rate of data that is transmitted toward two intermediate nodes is changed in order to control the load over a bearer that connects the two intermediate nodes.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a non-provisional patent application filed under 35 U.S.C. 371 and claiming priority to and the benefit of U.S. Provisional Application for Patent 60/890,496 filed on Feb. 18, 2007, through International Application PCT/IL2008/000179 filed on Feb. 12, 2008, of which both applications are hereby incorporated by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     The subject matter of the present disclosure relates to the field of cellular fixed networks and, more specifically, to providing improved Quality of Service (QoS) over a terrestrial radio access network. 
     The rapid evolution of communication over wireless communication networks for mobile communications, such as but not limited to, 2G networks, etc., creates a demand for increasing bandwidth over cellular fixed networks. The demand for increasing the bandwidth of the cellular fixed network pushes more and more cellular network operators to add data manipulation equipment between central nodes, such as but not limited to base station controllers (BSC), and its associated cells, such as but not limited to base transceiver stations (BTS). 
     Common manipulation equipment is capable of intercepting the data traffic on both sides of a bearer that carries cellular data between a central node and a cell over the cellular fixed network, and aggregating data units and/or manipulating the data in order to reduce the number of bits that are transmitted over the associated bearer. On the other side of the bearer, mating manipulation equipment de-manipulates the manipulated data into the original data format and the de-manipulated data is transmitted toward its final destination. Exemplary manipulation equipment may aggregate data units, reduce padding bits, idle data frames, unused data frames etc. Manipulation methods themselves are not part of the present disclosure and shall thus not be described in detail here. Detailed information about manipulation methods can be obtained from many sources. For example, U.S. patent application Ser. Nos. 11/194,918; 10/830,081; 11/408,418; and 11/464,204 disclose several types of manipulation equipments and methods. 
     Since manipulation equipment can reduce the volume of data over a bearer between a central node and a cell, the bearer associated with the manipulation equipment can carry more connections than a common bearer. Therefore, the central node and/or the cell can be configured as having two or more dummy bearers instead of the real one. Furthermore, common central nodes and/or cells have a mechanism that can control the bit-rate of the data that is created by a mobile telephone or cellular device in order to reduce the volume of the data over the network. For example, in a GSM fixed network, a BSC can change the bit-rate that is currently used by an adaptive multi-rate (AMR) codec for compressing the audio data to/from a cellular device. Such a mechanism may not be effective if the central node is configured as having more bearers than the real one. 
     Therefore, there is a need in the art for a system and method that can measure temporary load over a bearer that connects two nodes, such as a central node with a cell and change the bit-rate that is created by a source of data. Such a system can adapt the volume of the data to the capacity of a bearer and its associated manipulation equipment. Furthermore, such a system can lead a source of data, a cellular telephone or other cellular device for example, to change its data format in order to deliver a data format that can be manipulated more efficiently by the associated manipulation equipment. 
     Therefore, there is a need in the art for a system and method for leading a source of data to change its bit rate into another bit rate in order to match the load over a bearer and to improve the QoS and the utilization of the data manipulation equipment in reducing the number of bits that are transmitted over a cellular network. 
     BRIEF SUMMARY OF THE INVENTION 
     Exemplary embodiments of the present invention provide novel apparatus and improved methods for improving QoS over the cellular network, reducing the number of bytes that are transmitted over a bearer between two nodes, such as between a BSC and a BTS, for example. An exemplary apparatus can be capable of intercepting data units, such as but not limited to, Abis frames, which are transferred over a bearer between a BTS and a BSC, for example and changing certain control bits that lead a source of data, such as a cellular phone, to change the bit rate of the next data units in order to improve the QoS over the network and/or the efficiency of an associated manipulation device. 
     Exemplary embodiments of the present invention may parse a received Abis data frame in search of control bits that can influence the bit rate that is used by the destination of the current data frame. The destination of the current data frame will be the source of the next data frame which will be transferred in the other direction. An Abis frame that has a reduced bit rate data chunk can include more padding bits in order to reach the required size of an Abis frame (40 bytes, for example). The padding bits will be easily removed by a manipulation equipment, reducing the number of bits that are transmitted over the bearer. 
     An embodiment of the present invention may intercept data traffic over a bearer, parse the Abis frames, search for audio data frames that were compressed according to the AMR compression standard, and manipulate the control bits requesting the destination of the data frame to reduce the bit rate of its AMR encoder. 
     Other exemplary embodiments of the present invention can be adapted to establish a connection with a central controller of the cellular network (a BSC, or RNC for example) or with a source of data, a web-server, a video server, etc. The connection can be based on the Internet Protocol (TCP/IP, for example) or any other type of protocol that can be used between two devices. Over the connection, an indication about the current load over the bearer can be sent, requesting the central node or the server to reduce the bit rate that is sent toward the bearer. 
     Yet, another exemplary embodiment of the present invention may generate and send an indication to the associated node that one of the dummy bearers/trunks failed, thereby causing the node to reduce the load. In this disclosure, a trunk is used as an interchangeable term for a connection link between manipulation equipment and its associated node. 
     The foregoing summary is not intended to summarize each potential embodiment or every aspect of the present disclosure, and other features and advantages of the present disclosure will become apparent upon reading the following detailed description of the embodiments with the accompanying drawings and appended claims. 
     Furthermore, although specific exemplary embodiments are described in detail to illustrate the inventive concepts to a person skilled in the art, such embodiments are susceptible to various modifications and alternative forms. Accordingly, the Figures and written description are not intended to limit the scope of the inventive concepts in any manner. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
       Exemplary embodiments of the present invention will be understood and appreciated more fully from the following detailed description, taken in conjunction with the drawings in which: 
         FIG. 1  is a simplified block diagram illustrating an exemplary portion of a communication network in which an exemplary embodiment of the present invention is used; 
         FIG. 2  schematically illustrates a block diagram with relevant elements of an exemplary load reducer module (LRM) that operates according to certain teachings of the present disclosure; and 
         FIG. 3  illustrates a flowchart showing relevant steps of an exemplary bit-rate changer task at an exemplary LRM. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The disclosure can be further understood with reference to the drawings in which like numerals represent like elements throughout the several views. For convenience, only some elements of the same group may be labeled. The drawings illustrate examples of the disclosed embodiments and are not intended to limit the disclosure in any way. Therefore, features shown in the drawings are chosen for convenience and clarity of presentation only. 
       FIG. 1  illustrates a block diagram with relevant elements of a portion of an exemplary cellular network  100 . Cellular network  100  may comprise a plurality of mobiles terminals (MT)  110  wirelessly connected  112  to a fixed network. The fixed network can comprise a plurality of cells  120 , one or more central nodes  130  and a cellular operator&#39;s core network (COCN)  140 . A cell  120  is connected or communicatively coupled with the central node  130  via a bearer  114 . The central node  130  is connected or communicatively coupled with COCN  140  via communication line  134 . The COCN  140  can be connected via a circuit switch connection  146  to a Public Switched Telephone Networks (PSTN)  150  and via a packet switch connection  143  to the Internet  155 . In order to increase the utilization and/or improve the QoS over the fix network  100 , a pair of exemplary load reducer modules (LRM)  160  can be installed at each end of one or more bearers  114 . 
     Bearer  114  can be cable wires (e.g. the E1 link), fiber optics, or other communication links. The transportation over bearer  114  may be based on different types of communication protocols, including but not limited to the ATM protocol, TDM-A protocol, etc. Bearer  114  can comprise a single communication line carrying data in both directions, uplink or downlink. Alternatively, bearer  114  can comprise two or more communication lines with each one carrying data in one direction, uplink or downlink, or both. 
     The COCN  140  can include common cellular network elements, such as a mobile switching center (MSC), serving GPRS support node (SGSN), gateway GPRS support node (GGSN), home location register (HLR) etc. which are not shown in the drawings. Exemplary MTs  110  can include a cellular telephone, a PDA with cellular capabilities, or any other computerized device that can generate and/or receive audio, video, computer data or any combination of those via a cellular network. 
     Cell  120  is an intermediate node for radio transmission/reception with MT  110  that are currently located in a geographical area that is served by the Cell  120 . A single cell  120  can serve a plurality of MTs  110 . An exemplary cell can be a Base Transceiver Station (BTS). A plurality of cells  120  are administered by the central node  130 . An exemplary central node  130  can be a BSC (Base Station Controller), for example. Cell  120  can communicate with the central node  130  over bearer  114  using TDM-A network protocol implementing Abis interface as a layer  2  (Data Link layer) protocol, for example. When data is moving across the physical links  114  by using Abis interface, the data is divided into in Abis frames. 
     Central node  130  controls the plurality of cells  120  and MTs  110 , which are connected via the central node  130 . Among other tasks the central node  130  is responsible for centralized operation of the cells. It can switch data chunks, such as Abis frames for example, between the different cells  120 . Information on cellular network technology and operation is well known in the art and shall thus not be described in detail here. Detailed information about the function of cellular networks can be obtained from many sources and can be found in relevant web sites. 
     An exemplary embodiment of an LRM  160  is capable of adjusting the load that is transmitted toward the two nodes, cell  120  and central node  130  ( FIG. 1 ). Adjusting the load can be implemented, by an exemplary LRM  160 , by intercepting the data transportation over the relevant bearer  114 ; manipulating the data over one or, more channels that are established over the bearer and transferring the manipulated data toward a mating LRM  160  on the other end of the bearer  114 . The manipulated data has fewer bits than the original data. In addition, the LRM  160  is capable of changing the bit rate that is used over the connection between an MT  110  and the central node  120  via its associated wireless connection  112 , cell  120  and the relevant bearer  114 , wherein changing the bit-rate depends on the load over bearer  114  after manipulating received data. 
     On the other side of bearer  114 , in the mating LRM  160 , an exemplary de-manipulator module is capable of reconstructing the reorganized chunk of data into a legal format that matches the type of the session and the content of the payload of the original received data at the LRM  160 , which locates at the access of bearer  114 . However, although the exact content of the de-manipulated data can be different from the originally received data, the user experience is not affected. More information regarding the operation of an exemplary LRM  160  is disclosed below in conjunction with description of  FIG. 2  and  FIG. 3 . 
       FIG. 2  illustrates a block diagram with relevant elements of an exemplary embodiment of a load reducer module (LRM)  200  that operates according to certain, teachings of the present disclosure. The exemplary LRM  200  that is illustrated in  FIG. 2  can be used in a junction between a cell  120  or a central node  130  ( FIG. 1 ) and its associated bearer  114  ( FIG. 1 ) (i.e., units  160  in  FIG. 1 ). The LRM  200  may intercept the communication between a cell  120  or central node  130  and its relevant bearer  114 . Among other tasks, the LRM  200  can be adapted to analyze the volume of the data traffic received from the associated bearer. Based on the volume of the received traffic, an exemplary LRM  200  is capable of adjusting the load that is transmitted toward the two nodes, cell  120  and central node  130  ( FIG. 1 ). Adjusting the load can be implemented by an exemplary LRM  200  by changing certain control bits in data chunks that are sent toward the bearer. Such an operation will control the bit-rate that is currently used by one or more sources of the data that are located on the other side of the bearer. In addition, an exemplary LRM  200  may manipulate the data toward the bearer over the data link layer, to reduce the number of bits transmitted over the bearer. 
     In the other direction, from the bearer  114 , the LRM  200  can be adapted to de-manipulate the data chunks over the data link layer into a standard data chunk to be transmitted toward the associated cell  120  or central node  130  ( FIG. 1 ). 
     In some embodiments of the present invention, the LRM  200  can be adapted to receive QoS definitions. Based on the QoS definitions, the LRM  200  can manipulate the bit-rate of certain connections over the bearer. 
     An exemplary LRM  200  can be divided into two sections, a transmitting section and a receiving section. The transmitting section may comprise a Base station to Bearer IF module (BSTBIF)  212 , a bit-rate change module (BRC)  214 , a manipulator module (MM)  216  and an LRM to Bearer Interface module (LTBIF)  218 . In the other direction, a receiving section of the LRM  200  may comprise a Bearer to LRM interface module (BTLIF)  222 , a de-manipulator module (DMM)  224  and a bearer to base-station (a cell or a central node) interface module (BTBSIF)  226 . 
     The first pair of interfaces, BSTBIF  212  and LTBIF  218 , is associated with the transportation toward the bearer  114  ( FIG. 1 ), while the second pair of interfaces BTLIF  222  and BTBSIF  226  is associated with the transportation from the bearer  114  toward a base-station, a cell  120  or central node  130 . An exemplary BSTBIF  212  can get the data chunks that are transmitted over the physical link between a base station and the LRM  200 , and based on the media access control address, may deliver a plurality of media data units. In an embodiment of the present invention in which a base station is a BSC or BTS and the bearer is E1, then BSTBIF  212  can be adapted to receive E1 data units, process them according to Abis interface protocol and deliver Abis frames to BRC  214 . 
     De-manipulated standard data chunks of media from DMM  224  are transferred to the BTBSIF  226 . The BTBSIF  226  divides the data of the de-manipulated media data chunks into one or more payloads of E1 data units according to the E1 protocol, and sends the E1 data units toward its associated BTS  120  or BSC  130  ( FIG. 1 ) via bearer  114 . 
     Nonstandard media data units from MM  216  are transferred to the LTBIF  218 . The LTBIF  218  may divide the data of the nonstandard media data units into one or more E1 data units according to the E1 protocol; and send the E1 data units over bearer  114  ( FIG. 1 ) toward the mating LRM  160  on the other side of the connection. 
     An exemplary BTLIF  222  can get the transportation that is transferred from a mating LRM via bearer  114 . The BTLIF  222  receives the E1 data units, and processes the received E1 data units according to the E1 protocol to organize the data into nonstandard media data units. The nonstandard media data units are transferred to the DMM  224 . In addition to its data interfacing task, the BTLIF  222  can be adapted to monitor the volume of the received traffic, which reflects the load over bearer  114 . 
     In an exemplary embodiment of the present invention, monitoring the volume of the received traffic can be implemented by calculating the bit-rate of the currently received data from the bearer. The load over bearer  114  can be calculated as the percentage of the current received bit-rate from the maximum bit-rate of bearer  114 . Information on the load can be transferred to the BRC  214 . In one exemplary embodiment of the present invention, the BTLIF  222  can be adapted to measure the load periodically and to transfer the load indication to the BRC  214 . In an alternate embodiment, the BRC  214  may initiate a cycle of monitoring the load to be executed by the BTLIF  222 . 
     An exemplary MM  216  can operate to improve the bandwidth utilization over the bearer  114 . The MM  216  can be capable of aggregating media data units and/or manipulating the media data and/or organize the media data according to a non-standard data link protocol to be carried over the bearer  114 , etc. The outcome of the operation of the MM  216  is a reduction in the number of bits that are transmitted over the associated bearer. On the other side of the bearer, in a mating LRM  200 , an exemplary DMM  224  may convert the manipulated data into the original data format. An exemplary MM  216  may remove: padding bits, idle data frames, unused data frames, etc. Alternatively, or additionally, the MM  216  may further compress the media data, etc. Respectively, the DMM  224  may add the removed data such as padding bits, idle frames and/or decompress the further compression, etc. Detailed information about the function of a exemplary MM  216  and DMM  224  can be obtained from many sources. For example U.S. patent application Ser. Nos. 11/194,918; 10/830,081; 11/408,418 discloses several methods that can be implemented by exemplary embodiments of the MM  216  and DMM  224 . 
     An exemplary BRC  214  can be capable of receiving information about the volume of the data traffic that is carried over the bearer from the mating LRM. The information can be received from the BTLIF  222  as it is described above. If the received load is below a threshold level, then the media data chunks can be transferred as is from the BSTBIF  212  to the MM  216 . If the received load exceeds the threshold level, then the BRC  214  is adapted to parse the received media data chunks, such as payload of Abis frames, according to Abis protocol, and to search for certain control bits that lead a destination of the media to reduce its bit rate. The destination can be a cellular telephone or cellular device, for example. For an Abis frame carrying compressed audio based on AMR standard, an exemplary control bit can be C 23 , C 24 , and C 25  as well as the Request or Indication Flag (RIF) of the Abis frame. 
     Table 1 presents the requested AMR bit-rate along with the relation between a combination of the controls bit and relevant bit-rate: 
     
       
         
               
               
               
             
               
               
               
             
           
               
                   
                   
               
               
                   
                 Control bits combination 
                 AMR - Bit rate 
               
               
                   
                 C23; C24; C25 
                 (kbps) 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 0; 0; 0 
                 4.75 
               
               
                   
                 0; 0; 1 
                 5.15 
               
               
                   
                 0; 1; 0 
                 5.90 
               
               
                   
                 0; 1; 1 
                 6.70 
               
               
                   
                 1; 0; 0 
                 7.40 
               
               
                   
                 1; 0; 1 
                 7.95 
               
               
                   
                 1; 1; 0 
                 10.2 
               
               
                   
                 1; 1; 1 
                 12.2 
               
               
                   
                   
               
             
          
         
       
     
     If the value of RIF is zero, then the control bits C 23 , C 24 , and C 25  represent a request to an MT on the other end of the connection to change the bit-rate that is used by its AMR codec to the requested bit-rate. If the value of RIF is one, then the control bits C 23 , C 24 , and C 25  represent the bit-rate that was used in compressing the audio of the currently received and next Abis frame. 
     Based on the load indication that was received from the BTLIF  222  and the value of the RIF, an exemplary BRC  214  can change the value of the control bits C 23 , C 24 , and C 25 . In some embodiments of the present invention, the BRC  214  can be capable of reducing the value of the control bits when the load exceeds the threshold level. More information about the bit-rate changing process is disclosed below in the description of  FIG. 3 . 
     An alternate embodiment of the present invention may respond to low load over the bearer by changing the control bits in order to increase the bit rate in order to improve the quality of the audio session. 
     Other exemplary embodiments of the present invention (not shown in the drawing) can have a communication module instead of, or in addition to, the BRC  214 . The communication module can be capable of establishing a connection with a central controller of the cellular network (a BSC, or RNC for example) or with a source of data, a web-server, a video server, etc. The connection can be based on the Internet Protocol (TCP/IP, for example) or any other type of protocol that can be used between two devices. Over the connection, an indication about the current load, which was calculated by the BTLIF  222  can be sent, signaling to the central node or to the server to reduce the bit rate that is sent toward the bearer. 
     Yet, in another exemplary embodiment of the present invention, the BTLIF  222  may generate and send an indication to the associated node that one of the dummy bearers/trunks failed thereby causing the node to reduce the load. 
       FIG. 3  illustrates relevant steps of an exemplary process  300  for adjusting the bit-rate of a source of data that is transmitted toward the two intermediate nodes: cell  120  and central node  130  ( FIG. 1 ). The process  300  can be implemented by a Bit-Rate Changer (BRC)  214  ( FIG. 2 ). The process  300  can be initiated  302  upon the initiation of an LRM  200  ( FIG. 2 ) and may run as long as the LRM  200  is active. After initiation, the load of the traffic transmitted over the bearer  114  ( FIG. 1 ) toward the BRM  160  ( FIG. 1 ) is measured  222 . Measuring the load can be executed by the BTLIF  222 , for example. In an exemplary embodiment of the present invention, the BRC  214  may send a sampling command to the BTLIF  222 . In response, the BTLIF  222  may calculate the bit-rate that is currently being received via bearer  114 . The currently received bit-rate can be compared to the maximum bit rate that can be carried by the bearer  114 . The percentage of the currently received bit-rate from the maximum bit-rate of the bearer can be referred to as the load indication. The load indication can be transferred to the BRC  214 . Other embodiments may implement other types of measurements. For example, in other embodiments the LTBIF  218  ( FIG. 2 ) can be adapted to measure the current bit rate for data that is transmitted toward the bearer  114 . Yet in an alternate embodiment, both interfaces, the BTLIF  222  and the LTBIF  218  can be adapted to measure the current bit rate of data going to and from the bearer  114  and the BRC  214  can be adapted to make decisions on one or both the two measurements, etc. 
     At the end of the measuring process, timer T is reset  304 . Timer T is used for defining the sampling period of the load. A common sampling period (T1) can be on the order of a few tens of milliseconds up to a few seconds, for example. 
     After resetting the timer T, the process  300  may wait  310  for receiving a media data unit. An exemplary data unit can be an Abis frame. Upon receiving the media data unit, a decision is made by the BRC  214  as to whether  312  the bit-rate of the received data can be controlled. The decision can be based on the type of media that is currently carried over the connection. For example, an Abis frame carrying compressed audio according to the AMR protocol has the option to request a destination of the media data unit to change the bit-rate of its codec. If  312  the bit rate can not be controlled, then the Abis frame is transferred  336  toward the MM  216  ( FIG. 2 ) without any changes. For instance, media data units carrying compressed audio based on a Full Rate (FR) codec do not have the option of controlling the bit rate of the data that is created by the receiving end of an FR Abis frame, and as such, is passed without any changes. 
     If  312  the bit-rate can be controlled, then the data unit or frame is parsed  314  and a decision is made as to whether  320  the data unit carries an indication or a request. This decision can be based on the status of Request or Indication Flag (RIF). If the RIF=1, then this reflects a request. If the RIF=0, then this reflects an indication. If  320  the RIF reflects an indication, then the process  300  continues at step  336  and the received data unit is transferred as is to the MM  216 . If the RIF reflects a request, then control bits C 23 ; C 24  and C 25  are a request for a bit rate to be used by the codec of the destination of the data unit. The different combinations of the control bits are illustrates above in Table 1. 
     In case  320  that the control bits reflect a request to change the bit rate which is used by the codec of the destination of the data frame, then the current load indication is analyzed  330  and can be compared to a threshold level L 1 . The level L 1  can reflect a load that is close to the maximum capacity over the bearer, 80% of the maximum capacity for example. Some embodiments of the present invention may use other values for L 1 . The capacity of the bearer can be defined as the maximum bit rate that can be carried by the bearer, for example. 
     If  330  the current load over the bearer  114  ( FIG. 1 ) is less than the level L 1 , the control bits C 23 ; C 24  &amp; C 25  remain as is and the data unit is transferred  336  as is toward the manipulation module  216  ( FIG. 2 ). 
     If the current load indication is above the level L 1 , then the value of the control bits is decreased  332 , requesting a lower bit rate. A new cyclic redundancy code (CRC 1 ) is calculated to match the new value of C 23 ; C 24  &amp; C 25 . In case the value is already zero, which indicates the minimum bit rate of 4.75 Kbps (table 1), then the value of C 23 ; C 24  &amp; C 25  remain as is. After processing the control bits, the data frame is transferred  336  toward the manipulation module  216 . 
     After transferring the data frame toward the MM  216  ( FIG. 2 ), the timer T is checked and a decision is made whether  340  T is greater than T1. If T is greater than T1 the process  300  returns to step  304  for monitoring the current load received from the bearer. If T is smaller than T1, then the process  300  may return to step  310  waiting for the next data frame. 
     In the present disclosure, the words “unit,” “element,” “module” and “logical module” can be used interchangeably. Anything designated as a unit or module can be a stand-alone unit or a specialized or integrated module. A unit or a module can be modular or have modular aspects allowing it to be easily removed and replaced with another similar unit or module. Each unit or module may be any one of, or any combination of, software, hardware, and/or firmware. 
     In the description and claims of the present disclosure, “comprise,” “include,” “have,” and conjugates thereof are used to indicate that the object or objects of the verb are not necessarily a complete listing of members, components, elements, or parts of the subject or subjects of the verb. 
     It will be appreciated that the above described apparatus, systems and methods can be varied in many ways, including, changing the order of steps, and the exact implementation used. The described embodiments include different features, not all of which are required in all embodiments of the present disclosure. Moreover, some embodiments of the present disclosure use only some of the features or possible combinations of the features. Different combinations of features noted in the described embodiments will occur to a person skilled in the art. Furthermore, some embodiments of the present disclosure can be implemented by combination of features and elements that have been described in association to different exemplary embodiments along the discloser. The scope of the invention is limited only by the following claims.