Patent Publication Number: US-9408237-B1

Title: Random access preamble selection

Description:
This patent application is a continuation of U.S. application Ser. No. 13/742,999, filed on Jan. 16, 2013. 
    
    
     TECHNICAL BACKGROUND 
     A wireless device attempting to establish communication with a wireless communication network can send a request for a communication channel to an access node. The access node typically uses a procedure to allocate wireless link resources to the requesting wireless device, such as a random access procedure, which allocates wireless link resources on a request or need basis rather than establishing dedicated wireless link resources for the wireless device. A random access procedure can be used in a variety of circumstances, such as when a wireless device initiates communication when it comes out of a lower power or idle state, when a wireless device is attempting to re-establish a lost or temporarily dropped connection, when the wireless device is handed over to a second access node, or when data is available to be transferred between the access node and the wireless device. 
     Overview 
     In operation, a first plurality of random access preambles and a second plurality of random access preambles are stored at an access node. A random access channel request is received from a wireless device at the access node, the random access channel request comprising an application type of an application running on the wireless device. A network load, a priority class of the wireless device, and a mobility of the wireless device are determined. When the first plurality of random access preambles is not exhausted, the network load meets a load criteria, the priority class of the wireless device meets a priority criteria, the mobility of the wireless device meets a mobility criteria, and the application type of the application meets an application criteria, a random access preamble is assigned to the wireless device from the first plurality of random access preambles. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates an exemplary communication system for random access preamble selection. 
         FIG. 2  illustrates an exemplary method of random access preamble selection. 
         FIG. 3  illustrates another exemplary communication system for random access preamble selection. 
         FIG. 4  illustrates another exemplary method of random access preamble selection. 
         FIG. 5  illustrates an exemplary processing node. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  illustrates an exemplary communication system  100  for random access preamble selection comprising wireless device  102 , access node  104 , and communication network  106 . Examples of wireless device  102  can comprise a cell phone, a smart phone, a computing platform such as a laptop, palmtop, or tablet, a personal digital assistant, or an internet access device, including combinations thereof. Wireless device  102  is in communication with access node  104  over communication link  108 . 
     Access node  104  is a network node capable of providing wireless communications to wireless device  102 , and can be, for example, a base transceiver station, a radio base station, an eNodeB device, or an enhanced eNodeB device. Access node  104  is in communication with communication network  106  over communication link  110 . 
     Communication network  106  can be a wired and/or wireless communication network, and can comprise processing nodes, routers, gateways, and physical and/or wireless data links for carrying data among various network elements, including combinations thereof, and can include a local area network, a wide area network, and an internetwork (including the Internet). Communication network  106  can be capable of carrying voice information, for example, to support voice and data communications by a wireless device such as wireless device  102 . Wireless network protocols may comprise code division multiple access (CDMA) 1×RTT, Global System for Mobile communications (GSM), Universal Mobile Telecommunications System (UMTS), High-Speed Packet Access (HSPA), Evolution Data Optimized (EV-DO), EV-DO rev. A, Third Generation Partnership Project Long Term Evolution (3GPP LTE), and Worldwide Interoperability for Microwave Access (WiMAX). Wired network protocols that may be utilized by communication network  106  comprise Ethernet, Fast Ethernet, Gigabit Ethernet, Local Talk (such as Carrier Sense Multiple Access with Collision Avoidance), Token Ring, Fiber Distributed Data Interface (FDDI), and Asynchronous Transfer Mode (ATM). Communication network  106  may also comprise additional base stations, controller nodes, telephony switches, internet routers, network gateways, computer systems, communication links, or some other type of communication equipment, and combinations thereof. 
     Communication links  108  and  110  can be wired or wireless communication links. Wired communication links can be, for example, twisted pair cable, coaxial cable or fiber optic cable, or combinations thereof. Wireless communication links can be a radio frequency, microwave, infrared, or other similar signal, and can use a suitable communication protocol, for example, Global System for Mobile telecommunications (GSM), Code Division Multiple Access (CDMA), Worldwide Interoperability for Microwave Access (WiMAX), or Long Term Evolution (LTE), or combinations thereof. Other wireless protocols can also be used. 
     Other network elements may be present in the communication system  100  to facilitate wireless communication but are omitted for clarity, such as base stations, base station controllers, gateways, mobile switching centers, dispatch application processors, and location registers such as a home location register or visitor location register. Furthermore, other network elements may be present to facilitate communication between access node  104  and communication network  106  which are omitted for clarity, including additional processing nodes, routers, gateways, and physical and/or wireless data links for carrying data among the various network elements. 
     In operation, a first plurality of random access preambles and a second plurality of random access preambles are stored at access node  104 . A random access channel request is received from wireless device  102  at access node  104 , where the random access channel request comprises an application type of an application running on wireless device  102 . A network load, a priority class of wireless device  102 , and a mobility of wireless device  102  are determined. When the first plurality of random access preambles a access node  104  is not exhausted, the network load meets a load criteria, the priority class of wireless device  102  meets a priority criteria, the mobility of wireless device  102  meets a mobility criteria, and the application type of the application meets an application criteria, a random access preamble is assigned to wireless device  102  from the first plurality of random access preambles. In an embodiment, a current activity of wireless device  102  can also be considered. In an embodiment, an activity history of wireless device  102  can also be considered. Further, when the first plurality random access preambles is exhausted, wireless device  102  can be assigned a random access preamble from the second plurality of random access preambles, without requiring wireless device  102  to delay the RACH process. 
       FIG. 2  illustrates an exemplary method of random access preamble selection. In operation  202 , a first plurality of random access channel preambles and a second plurality of random access preambles are stored. A wireless device attempting to establish communication with a wireless communication network typically sends a request for a communication channel to an access node. The access node typically uses a procedure to allocate wireless link resources to the requesting wireless device, such as a random access procedure, which allocates wireless link resources on a request or need basis rather than establishing dedicated wireless link resources for the wireless device. A random access procedure can be contention based or non-contention based. In an embodiment, the second plurality of random access preambles can be assigned to a wireless device when the first plurality of random access preambles is exhausted. 
     In a contention based random access procedure, a wireless device typically sends a channel request over a randomly selected random access channel (RACH). The channel request can comprise a random access preamble. When a channel request is received from the wireless device, the receiving access node can provide an indication that access is permitted, such as a positive indication in a random access response, an acquisition indication, or a similar message. After receiving the indication that access is permitted the wireless device can send a scheduled transmission of data to the access node. Following the scheduled transmission of data from the wireless device, the access node may send out a contention resolution message indicating that the transmission was successfully received. When the wireless device does not receive a success indication, the wireless device may re-initiate the contention based random access procedure. A contention based random access procedure can be used when, for example, a wireless device is handed over from one access node to another access node, when a wireless device exits an idle mode and attempts to re-establish communication with an access node, when a wireless device temporarily loses communication with an access node and attempts to re-establish communication, when data is available to be transmitted from the wireless device to the access node, or vice versa, and the like. 
     In a non-contention based random access procedure, an access node can assign a random access preamble to a wireless device, which the wireless device can use in a channel request which it sends to the access node. The access node can then respond to the channel request with a random access response. A non-contention based random access procedure can be used, for example, during a handover of a wireless device, or when a wireless device is notified that data is available for the wireless device, for example, by a paging procedure or similar procedure. 
     A random access procedure can use a group of preambles based on a first-come first-served basis, wherein a wireless device can select at random from the group of preambles. For example, when wireless device  102  initiates communication with access node  104 , wireless device can receive information broadcast by access node  104  and select a random access preamble based on the received information. However, as a number of wireless devices initiating communication with access node  104  increases, the possibility of random access request collision or random access preamble collision increases, which can lead to channel requests from wireless devices being rejected and causing delay in establishing communication links with wireless devices. Greater efficiency can be achieved by using additional factors to select a random access preamble. 
     In operation  202 , a first plurality of random access preambles and a second plurality of random access preambles is stored. For example, the first and second pluralities of random access preambles can be stored at access node  104 . In an embodiment, the first plurality of random access preambles can be a dedicated group of random access preambles which is preselected for assignment to a wireless device. The availability of the first and second plurality of random access preambles can be provided by access node  104  to wireless device  102 . For example, access node  104  can broadcast information, such as in a SIB message or other similar message, to provide information to wireless device  102  about random access preamble allocation. 
     In operation  204 , a request for a RACH is received. For example, access node  104  can receive a RACH request from wireless device  102 . The request for the RACH can comprise additional information from wireless device  102 , such as an application running on wireless device  102 . The RACH request can also comprise information such as a priority class of wireless device  102 , a location and/or an indication of mobility of wireless device  102 , a received power level of communication link  108 , a received signal quality, and the like. A priority class of a wireless device can comprise a priority service level associated with the wireless device. For example, a wireless device intended for use by emergency response personnel, or by a premium customer, can be associated with a higher priority service level, to prioritize the assignment of wireless link resources to the wireless device. One example of such a priority service level is an allocation and retention priority. A priority class of a wireless device can also comprise a priority of certain kinds of information sent by the wireless device, such as data assigned a guaranteed bit rate, minimum throughput, maximum permitted delay, and the like. For example, data sent by a delay sensitive application running on the wireless device, such as a voice application or a streaming application (such as streaming audio or video), can be associated with a higher priority class than data sent by a non-delay sensitive application such as a web browsing application or an email application. 
     In operation  206 , a network load, a priority class of the wireless device, and a mobility of the wireless device are determined. In an embodiment, information related to the priority class and mobility of the wireless device can be received at access node  104  in a RACH request from wireless device  102 . In an embodiment, this information can be determined by access node  104 , or it can be received at access node  104  from another network element of communication system  100 . 
     In operation  208 , a random access preamble is assigned to the wireless device from the first plurality of random access preambles when the first plurality of random access preambles is not exhausted, the network load meets a load criteria, the priority class of the wireless device meets a priority criteria, the mobility of the wireless device meets a mobility criteria, and the application type of the application meets an application criteria. For example, based on the received RACH request, access node  104 , or another element of communication system  100 , can determine that at least one random access preamble is in the first plurality of random access preambles. 
     Further, it can be determined that a network load meets a load criteria. For example, access node  104  can receive a threshold number of RACH requests in a period of time. As another example, a threshold number of wireless devices can be in communication with access node  104  at the time the RACH request is received from wireless device  102 . As another example, an amount of data traffic sent or received by access node  104  can meet a threshold data traffic level. A network load can also comprise a backhaul congestion or utilization, which can meet a threshold level of congestion (or utilization). Other examples of a network load meeting a load criteria are also possible, including combinations of the foregoing. 
     It can also be determined that the priority class of the wireless device meets a priority criteria. For example, it can be determined that a priority class of wireless device  102  is meets a priority class required for access to the first plurality of random access preambles. In examples, the priority class of the wireless device can be a priority class provisioned by communication system  100 , or it can be based on a type of data which is to be sent or received by wireless device  102 . 
     It can further be determined that a mobility of the wireless device meets a mobility criteria. For example, wireless device  102  can be relatively stationary within a coverage area of access node  104 . As another example, a mobility wireless device  102  can meet a threshold level of mobility within the coverage area of access node  104 . The mobility of the wireless device can also be considered with a network load of access node  104 . For example, when access node  104  is providing communications to a threshold level of wireless devices, or when access node  104  receives a threshold level of RACH requests in a period of time, random access preambles from the first plurality of random access preambles may be preferentially assigned to wireless devices which are relatively stationary within a coverage area of access node  104 . 
     In addition, it can be determined that a type of application running on the wireless device meets an application criteria. For example, it can be determined that an application running on wireless device  102  is a delay sensitive application, such as a voice application or a video or audio streaming application. 
     Thus, when the first plurality of random access preambles is not exhausted, the network load meets a load criteria, the priority class of the wireless device meets a priority criteria, the mobility of the wireless device meets a mobility criteria, and the application type of the application meets an application criteria, a random access preamble is assigned to the wireless device from the first plurality of random access preambles. 
       FIG. 3  illustrates another exemplary communication system  300  for random access preamble selection comprising wireless devices  302  and  304 , access node  306 , and communication network  308 . Examples of wireless devices  302  and  304  can comprise a cell phone, a smart phone, a computing platform such as a laptop, palmtop, or tablet, a personal digital assistant, or an internet access device, including combinations thereof. Wireless device  302  is in communication with access node  306  over communication link  310 , and wireless device  304  is in communication with access node  306  over communication link  312 . 
     Access node  306  is a network node capable of providing wireless communications to wireless devices  302  and  304 , and can be, for example, a base transceiver station, a radio base station, an eNodeB device, or an enhanced eNodeB device. Access node  304  is in communication with communication network  308  over communication link  314 . 
     Communication network  308  can be a wired and/or wireless communication network, and can comprise processing nodes, routers, gateways, and physical and/or wireless data links for carrying data among various network elements, including combinations thereof, and can include a local area network, a wide area network, and an internetwork (including the Internet). Communication network  106  can be capable of carrying voice information, for example, to support voice and data communications by a wireless device such as wireless device  302  or  304 . Wireless network protocols may comprise code division multiple access (CDMA) 1×RTT, Global System for Mobile communications (GSM), Universal Mobile Telecommunications System (UMTS), High-Speed Packet Access (HSPA), Evolution Data Optimized (EV-DO), EV-DO rev. A, Third Generation Partnership Project Long Term Evolution (3GPP LTE), and Worldwide Interoperability for Microwave Access (WiMAX). Wired network protocols that may be utilized by communication network  308  comprise Ethernet, Fast Ethernet, Gigabit Ethernet, Local Talk (such as Carrier Sense Multiple Access with Collision Avoidance), Token Ring, Fiber Distributed Data Interface (FDDI), and Asynchronous Transfer Mode (ATM). Communication network  308  may also comprise additional base stations, controller nodes, telephony switches, internet routers, network gateways, computer systems, communication links, or some other type of communication equipment, and combinations thereof. 
     Communication links  310 ,  312  and  314  can be wired or wireless communication links. Wired communication links can be, for example, twisted pair cable, coaxial cable or fiber optic cable, or combinations thereof. Wireless communication links can be a radio frequency, microwave, infrared, or other similar signal, and can use a suitable communication protocol, for example, Global System for Mobile telecommunications (GSM), Code Division Multiple Access (CDMA), Worldwide Interoperability for Microwave Access (WiMAX), or Long Term Evolution (LTE), or combinations thereof. Other wireless protocols can also be used. 
     Other network elements may be present in the communication system  300  to facilitate wireless communication but are omitted for clarity, such as base stations, base station controllers, gateways, mobile switching centers, dispatch application processors, and location registers such as a home location register or visitor location register. Furthermore, other network elements may be present to facilitate communication between access node  306  and communication network  308  which are omitted for clarity, including additional processing nodes, routers, gateways, and physical and/or wireless data links for carrying data among the various network elements. 
       FIG. 4  illustrates another exemplary method of random access preamble selection. In operation  402 , a first plurality of random access preambles and a second plurality of random access preambles is stored. For example, the first and second pluralities of random access preambles can be stored at access node  306 . In an embodiment, the first plurality of random access preambles can be a dedicated group of random access preambles which is preselected for assignment to a wireless device. The availability of the first and second plurality of random access preambles can be provided by access node  306  to wireless devices  302  and  304 , for example, in a broadcast message, such as in a SIB message or other similar message, to provide information to wireless devices  302  and  304  about random access preamble allocation. 
     In operation  404 , a request for a RACH is received. For example, access node  306  can receive a RACH request from wireless device  302 . The request for the RACH can comprise additional information from wireless device  302 , a current activity of wireless device  302 , such as an application running on wireless device  302 , whether wireless device  302  is running multiple applications and the application type of those applications, and whether wireless device  302  is providing network communication access for another wireless device (for example, where wireless device  302  is serving as a “mobile hotspot” or other similar function). The RACH request can also comprise an activity history of wireless device  302 , such as historical information related to applications run on wireless device  302 , whether wireless device  302  has run multiple applications and the application type of those applications, and whether wireless device  302  has provided network communication access for another wireless device. The activity history can also comprise an indication of whether wireless device  302  has been in a low power or idle mode, or has not been in an idle mode, for a period of time. In an embodiment, the current activity and the activity history of wireless device  302  can also be determined by access node  306  based on information from wireless device  302  and/or from another network element of communication system  300 . 
     The RACH request can also comprise information such as a priority class of wireless device  302 , a location and/or an indication of mobility of wireless device  302 , a received power level of communication link  310 , a received signal quality, and the like. A priority class of a wireless device can comprise a priority service level associated with the wireless device. For example, a wireless device intended for use by emergency response personnel, or by a premium customer, can be associated with a higher priority service level, to prioritize the assignment of wireless link resources to the wireless device. One example of such a priority service level is an allocation and retention priority. A priority class of a wireless device can also comprise a priority of certain kinds of information sent by the wireless device, such as data assigned a guaranteed bit rate, minimum throughput, maximum permitted delay, and the like. For example, data sent by a delay sensitive application running on the wireless device, such as a voice application or a streaming application (such as streaming audio or video), can be associated with a higher priority class than data sent by a non-delay sensitive application such as a web browsing application or an email application. 
     In operation  406 , a network load, a priority class of the wireless device, a mobility of the wireless device, a current activity of the wireless device, and an activity history of the wireless device are determined. In an embodiment, information related to the priority class and mobility of the wireless device can be received at access node  306  in a RACH request from wireless device  302 . In an embodiment, this information can be determined by access node  306 , or it can be received at access node  306  from another network element of communication system  300  (such as an home subscriber server (HSS), home location register (HLR), a mobility management entity (MME), or another network element). 
     In operation  408 , based on the determined network load the first plurality of random access preambles and the second plurality of random access preambles are adjusted based. For example, access node  306 , or another network element of communication system  300 , can determine that the network load meets a threshold load, and random access preambles can be added to or removed from the first plurality of random access preambles. The random access preambles can be removed from or added to the second plurality of random access preambles. In an embodiment, when a number of wireless devices with a high priority class increases (where the wireless devices are in communication with access node  306 , or requesting a channel from access node  306 ), available random access preambles can be added to the first plurality of random access preambles from the second plurality of random access preambles. Similarly, when a number of wireless devices with a high priority class decreases, random access preambles can be removed from the first plurality of random access preambles and added to the second plurality of random access preambles. In an embodiment, a network load can comprise a number of wireless devices in communication with an access node, an amount of data in transmission and/or scheduled for transmission between the access node and wireless devices, the priority level or class of wireless devices in communication with the access node, the priority level or class of data traffic, backhaul utilization or congestion, and the like. 
     In addition, the priority criteria can be adjusted based on the determined network load. For example, as a network load changes, the criteria can be adjusted for determining whether a wireless device (such as wireless device  302 ) is associated with a sufficient priority class to be assigned a random access preamble from the first plurality of random access preambles. In an embodiment, when the network load increases, the priority criteria can be adjusted to require a higher priority class to be assigned a random access preamble from the first plurality of random access preambles. 
     Further, the mobility criteria can be adjusted based on the determined network load. For example, as a network load increases, the mobility criteria can be adjusted so that users associated with a threshold level of mobility are not assigned a random access preamble from the first plurality of random access preambles. Highly mobile wireless devices can be expected to remain in communication with access node  306  for less time than a less mobile or relatively stationary wireless device. Reducing the allocation of random access preambles from the first plurality of random access preambles to highly mobile wireless devices can thus more efficiently allocate communication link resources. 
     The adjustment of the distribution of random access preambles into the first and second pluralities of random access preambles can also be time based. For example, in a case where access node  306  were located along a commuter highway, during typical times of heavy commuting wireless devices in the coverage area of access node  306  would exhibit high mobility, and further, access node could be highly loaded during commuting times. Based on such determined conditions, the allocation of random access preambles to the first and second pluralities of random access preambles can be adjusted, for example, to assign random access preambles from the first plurality of random access preambles to fewer wireless devices, due at least in part to the high mobility of most wireless devices experienced by access node  306  during commuting times. Similarly, outside of heavy commuting times, wireless devices in the coverage area of access node  306  may not be highly mobile (for example, when wireless devices tend to be at work, or at home). In such case, the allocation of random access preambles to the first and second pluralities of random access preambles can be adjusted, for example, to assign random access preambles from the first plurality of random access preambles to a greater number of wireless devices. 
     In operation  410 , it can be determined whether the random access preambles in the first plurality of random access preambles is exhausted. When a random access preamble remains in the first plurality of random access preambles (operation  410 —NO), the wireless device is assigned a random access preamble from the first plurality of random access preambles, for example, when the network load meets a load criteria, the priority class of the wireless device meets a priority criteria, the mobility of the wireless device meets a mobility criteria, and the application type of the application meets an application criteria. 
     In an embodiment, the wireless device can be assigned a random access preamble from the first plurality of random access preambles when the first plurality of random access preambles is not exhausted, the network load meets a load criteria, the priority class of the wireless device meets a priority criteria, the mobility of the wireless device meets a mobility criteria, the application type of the application meets an application criteria; and the current activity of the wireless device meets a current activity criteria. 
     In an embodiment, the wireless device can be assigned a random access preamble from the first plurality of random access preambles when the first plurality of random access preambles is not exhausted, the network load meets a load criteria, the priority class of the wireless device meets a priority criteria, the mobility of the wireless device meets a mobility criteria, the application type of the application meets an application criteria; and the activity history of the wireless device meets an activity history criteria. 
     When the first plurality of random access preambles is exhausted (operation  410 -YES), it can be determined whether there is a collision between the RACH request received from the wireless device and a second RACH request received from a second wireless device (operation  416 ). For example, wireless devices  302  and  304  can both send requests for a RACH to access node  306 . A conflict between the two RACH requests is possible. When no conflict or collision occurs (operation  416 -NO), a random access preamble can is assigned to the wireless device from the second plurality of random access preambles (operation  414 ). 
     When a RACH collision does occur (operation  414 -YES), the second wireless device is instructed to delay re-sending a RACH request, for example, by use of a back-off timer or other delay mechanism (operation  418 ). In such case, the first wireless device is not instructed to delay (for example, is not instructed to use a back-off timer), and thus the first wireless device—which met the various criteria described above may re-initiate the RACH process without additional delay. In operation  420 , the first wireless device can be assigned a random access preamble from the second plurality of random access preambles. For example, where RACH requests from wireless devices  302  and  304  collide or conflict, assignment of a random access preamble from the second plurality of random access preambles can be given to wireless device  302 , which satisfied the various criteria to be assigned a random access preamble from the first plurality of random access preambles, over wireless device  304 , when wireless device  304  does not meet one or more of the various criteria. 
     In an embodiment, wireless device  302  can send a RACH request to access node  306 . Wireless device  302  can be, for example, in an idle mode, and can perform cell reselection of access node  306 . When wireless device  302  performs cell reselection of access node  306 , access node  306  can receive a request for a RACH from wireless device  302 . A network load, a priority class of wireless device  302 , and a mobility of wireless device  302  can be determined. In addition, a current activity and an activity history of wireless device  302  can be determined. Where, for example, it is determined that access node  306  is heavily loaded (for example, through demand for services, or by a number of wireless devices requesting or being provided services), and wireless device  302  reports that it will use a delay sensitive application, and wireless device  302  is not highly mobile, a random access preamble from the first plurality of random access preambles can be assigned to wireless device  302 . In the event that the first plurality of random access preambles is exhausted, wireless device  302  may be assigned a random access preamble from the second plurality of random access preambles, without being required to delay re-initiation of the RACH process when a collision occurs with another wireless devices. 
     In an embodiment, wireless device  302  can be in active communication with access node  306 , and can send a RACH request to access node  306 . For example, wireless device  302  can exit an idle mode and attempt to establish active communication with access node  306 , or wireless device  302  can be handed over to access node  306 . Access node  306  can receive a request for a RACH from wireless device  302 . A network load, a priority class of wireless device  302 , and a mobility of wireless device  302  can be determined. In addition, a current activity and an activity history of wireless device  302  can be determined. Where, for example, it is determined that access node  306  is lightly loaded (for example, through demand for services, or by a number of wireless devices requesting or being provided services), and wireless device  302  reports that it will use a delay sensitive application, and wireless device  302  is not highly mobile, a random access preamble from the first plurality of random access preambles can be assigned to wireless device  302 . In addition, access node  306  (or another network element of communication system  300 ) can adjust the allocation of random access preambles to the first and second pluralities of random access preambles based on, for example, the determined network load, and/or the utilization of communication link resources of access node  306 . 
       FIG. 5  illustrates an exemplary processing node  500  in a communication system. Processing node  500  comprises communication interface  502 , user interface  504 , and processing system  506  in communication with communication interface  502  and user interface  504 . Processing node  500  is capable of methods of random access preamble selection. Processing system  506  includes storage  508 , which can comprise a disk drive, flash drive, memory circuitry, or other memory device. Storage  508  can store software  510  which is used in the operation of the processing node  500 . Storage  508  may include a disk drive, flash drive, data storage circuitry, or some other memory apparatus. Software  510  may include computer programs, firmware, or some other form of machine-readable instructions, including an operating system, utilities, drivers, network interfaces, applications, or some other type of software. Processing system  506  may include a microprocessor and other circuitry to retrieve and execute software  510  from storage  508 . Processing node  500  may further include other components such as a power management unit, a control interface unit, etc., which are omitted for clarity. Communication interface  502  permits processing node  500  to communicate with other network elements. User interface  504  permits the configuration and control of the operation of processing node  500 . 
     Examples of processing node  500  include access node  104  and access node  306 . Processing node  500  can also be an adjunct or component of a network element, such as an element of access node  104  or access node  306 . Processing node  500  can also be another network element in a communication system. 
     The exemplary systems and methods described herein can be performed under the control of a processing system executing computer-readable codes embodied on a computer-readable recording medium or communication signals transmitted through a transitory medium. The computer-readable recording medium is any data storage device that can store data readable by a processing system, and includes both volatile and nonvolatile media, removable and non-removable media, and contemplates media readable by a database, a computer, and various other network devices. 
     Examples of the computer-readable recording medium include, but are not limited to, read-only memory (ROM), random-access memory (RAM), erasable electrically programmable ROM (EEPROM), flash memory or other memory technology, holographic media or other optical disc storage, magnetic storage including magnetic tape and magnetic disk, and solid state storage devices. The computer-readable recording medium can also be distributed over network-coupled computer systems so that the computer-readable code is stored and executed in a distributed fashion. The communication signals transmitted through a transitory medium may include, for example, modulated signals transmitted through wired or wireless transmission paths. 
     The above description and associated figures teach the best mode of the invention. The following claims specify the scope of the invention. Note that some aspects of the best mode may not fall within the scope of the invention as specified by the claims. Those skilled in the art will appreciate that the features described above can be combined in various ways to form multiple variations of the invention. As a result, the invention is not limited to the specific embodiments described above, but only by the following claims and their equivalents.