Abstract:
Systems and techniques for data traffic management are described. A base station providing data communication services to user devices and capable of transferring traffic to one or more wireless network access points receives data queuing latency information relating to data queuing latency experienced by the one or more user devices, access points, or both. The base station makes determinations relating to offloading of traffic to access points, such as from wireless cellular network frequencies to wireless local area network resources, based on the latency information.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates generally o wireless communication. More particularly, the invention relates to improved systems and techniques for the use of latency measurements for management of offloading of network traffic. 
       BACKGROUND 
       [0002]    As the number of wireless cellular data communication devices continues to increase and as their data capabilities continue to be more and more heavily used, the demands on the available frequencies dedicated to cellular data communication comes closer and closer to saturation. One approach to the management of traffic load is the offloading of traffic onto unlicensed frequencies, such as those used by wireless local area networks (WLAN), whose presence may be represented by one or more access points (APs). Network operators may implement wireless network infrastructure, which uses unlicensed frequencies, and manage the transfer of traffic between base stations using licensed frequencies and unlicensed network access points. Such an approach may be used, for example, by 3rd Generation Partnership Project (3GPP) long term evolution (LTE) or LTE-advanced (LTE-A) networks. The efficient use of unlicensed frequencies and the efficient transfer of traffic between licensed frequencies and access points using unlicensed frequencies has the potential to greatly increase wireless data capacity. 
       SUMMARY 
       [0003]    In one embodiment of the invention, an apparatus comprises at least one processor and memory storing computer program code. The memory storing the computer program code is configured to, with the at least one processor, cause the apparatus to at least receive packet queuing latency information relating to data traffic between a user device and a wireless local area network access point and determine allocation of communication traffic to the wireless local area network access point based on the at least one packet queuing latency measurement. 
         [0004]    In one embodiment of the invention, an apparatus comprises at least one processor and memory storing computer program code. The memory storing the computer program code is configured to with the at least one processor, cause the apparatus to at least configure measurement of packet queuing latency between a user device and a wireless local area network access point and cause transmission of measurement information to a base station making a determination relating to offloading data traffic to the wireless local area network access point. 
         [0005]    In another embodiment of the invention, a method comprises receiving packet queuing latency information relating to data traffic between a user device and a wireless local area network access point and determining allocation of communication traffic to the wireless local area network access point based on the at least one packet queuing latency measurement. 
         [0006]    In another embodiment of the invention, a method comprises configuring measurement of packet queuing latency between a user device and a wireless local area network access point and causing transmission of measurement information to a base station making a determination relating to offloading data traffic to the wireless local area network access point. 
         [0007]    In another embodiment of the invention, a computer-readable medium stores a program of instructions. Execution of the program of instructions by a processor configures an apparatus to at least receive packet queuing latency information relating to data traffic between a user device and a wireless local area network access point and determine allocation of communication traffic to the wireless local area network access point based on the at least one packet queuing latency measurement. 
         [0008]    In another embodiment of the invention, a computer-readable medium stores a program of instructions. Execution of the program of instructions by a processor configures an apparatus to at least configure measurement of packet queuing latency between a user device and a wireless local area network access point and cause transmission of measurement information to a base station making a determination relating to offloading data traffic to the wireless local area network access point. 
         [0009]    In another embodiment of the invention, an apparatus comprises means for receiving packet queuing latency information relating to data traffic between a user device and a wireless local area network access point and means for determining allocation of communication traffic to the wireless local area network access point based on the at least one packet queuing latency measurement. 
         [0010]    In another embodiment of the invention, the apparatus comprises means for configuring measurement of packet queuing latency between a user device and a wireless local area network access point; and means for causing transmission of measurement information to a base station. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  illustrates a graph illustrating throughput gains that can be achieved through offloading of wireless network traffic to WLANs; 
           [0012]      FIG. 2  illustrates a graph illustrating the relationship between packet queuing delay and the number of WLAN active users under different conditions; 
           [0013]      FIG. 3  illustrates a wireless network according to an embodiment of he present invention; 
           [0014]      FIG. 4  illustrates a process according to an embodiment of the present invention; 
           [0015]      FIGS. 5 and 6  illustrate reporting procedures according to embodiments of the present invention; 
           [0016]      FIG. 7  illustrates a packet data unit including a timestamp according to an embodiment of the present invention; and 
           [0017]      FIG. 8  illustrates elements for carrying out embodiments of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0018]    Embodiments of the present invention recognize that offloading of data traffic to a wireless network, such as a wireless local area network (WLAN) made much more effective if decisions about when to offload traffic to WLAN and when traffic can no longer be offloaded to WLAN are properly guided. Embodiments of the invention further recognize that overall WLAN latency can be used as a criterion for making offloading decisions, and can generally be relied on to be proportional to the number of users. 
         [0019]      FIG. 1  illustrates a chart  100  showing throughput that can be achieved by varying levels of WLAN offloading with the criteria for offloading expressed in various delay thresholds. The plots  102 A- 102 E illustrate LTE downlink throughput for a delay threshold of 0, 10, 20, 40, and 60 ms, respectively, the plots  104 A- 104 E illustrate LTE uplink throughput, the plots  106 A- 106 F illustrate total downlink throughput, and the plots  108 A- 108 F illustrate total uplink throughput. No WLAN participation is shown for the 0 ms threshold, because a 0 delay threshold is not achievable so that no offloading occurs. However, WLAN participation is illustrated by the plots  110 B- 110 F and  112 B- 112 F for the thresholds ranging from 10 ms through 60 ms and for no threshold. If no threshold is used, all traffic is offloaded to the WLAN elements, so that the total throughput represents WLAN throughput. 
         [0020]      FIG. 2  illustrates a graph  200  showing a plot of latency, expressed in terms of queuing delay, plotted against the number of active users, for different proportions of WLAN usage. Latency represents overall packet queuing latency, which is the packet queuing latency from a WLAN access point (AP) and all user devices connected to it. In a system such as a 3rd Generation Partnership Project (3GPP) long term evolution (LTE) or LTE-advanced (LTE-A) system, the user device may be referred to as a user equipment (UE). The use of both uplink and downlink measurements is greatly beneficial for determining latency. In downlink, measurements may be measured at the WLAN AP, which may be communicated to a base station. The base station may be implemented as an eNodeB (eNB). The measurements may be communicated to an eNB. Such communication may be accomplished, for example, through a proprietary interface, through a core network, or via IP connectivity. In an uplink, measurements are obtained by the UEs, but such information is not generally available at the wireless LAN access point. 
         [0021]    Embodiments of the invention therefore provide mechanisms for determining uplink packet queuing latency for different UEs connected to the same access point. A wireless network and an eNB may have a connection, which may be either logical or physical, allowing exchange of downlink latency information between the AP and the eNB. Embodiments of the invention also provide mechanisms allowing either or both of an eNB or a WLAN AP to receive information on a UE&#39;s queuing latency information in the uplink direction during a WLAN connection. 
         [0022]      FIG. 3  illustrates a wireless network  300  according to an embodiment of the present nvention. The network  300  includes a core network  302 . eNB  304 . and access points  306 ,  308 , and  310 . The network  300  supports UEs  312 A- 312 E, and is able to offload traffic from the eNB  304  to one or more of the access points  306 ,  308 , and  310 . The eNB  304  makes offloading decisions based on packet queuing latency measurements, including devices connected to WLAN APs. The eNB  302  may collect packet queuing latency information from UEs connected to the same WLAN AP and from the connected WLAN APs themselves. For example, if the macro eNB is determining whether o offload the traffic of the UE  312 C to the AP  306 , the eNB  302  may collect packet queuing latency information from the UE  312 A and  312 B and the AP  306 , provided that UE  312 A and UE 312 B have offloaded traffic via the AP  306 . The eNB makes the offloading decision based on the collected latency information. In at least one embodiment of the invention, latency information ion is delivered to the eNB  302  by UEs, rather than by APs or UEs plus APs. 
         [0023]      FIG. 4  illustrates a process  400  of traffic management according to one or more embodiments of the present invention. The process  400  comprises measurement configuration, actual latency measurement, reporting of latency information to a network, and making and carrying out of offloading decisions by the network. 
         [0024]    At block  402 , a measurement configuration is performed. For example, in the case of the network  300 , a measurement configuration may be determined that is applicable for a UE in a radio resource control connected (RRC_CONNECTED) state by means of dedicated signaling, such as through the use of an RRCConnectionReconfiguration message defined in the 3GPP technical specification 36.331. Such configuration may include, for example, a trigger for measuring WLAN packet queuing latency, an indication of whether the measurement is periodic or non-periodic, and measurement triggers for a non-periodic measurement, or the periodicity for a periodic measurement. 
         [0025]    One example of WLAN packet queuing latency may be a delay starting when a device has a non-empty transmit media access control (MAC) buffer and stopping when data extracted from the buffer (that is, when the device has a transmit opportunity or when the device has successfully transmitted the packet). 
         [0026]    At block  404 , latency measurements may be performed at one or more of the UEs and/or the WLAN AP or APs being considered for offloading. The WLAN latency in the uplink direction may be measured at the UEs, while the measurement in the downlink direction may be carried out at WLAN APs. The AP may report its downlink direction measurements to the UEs, and receiving such information enables the UEs to report both uplink and downlink latency information to the network. 
         [0027]    At block  406 , latency measurements are reported to a network—for example, to an eNB making offloading decisions for UEs whose traffic is being considered for offloading and for WLAN APs being considered for being assigned the traffic. At step  408 , the network makes offloading decisions based on the reported measurement information. 
         [0028]    The WLAN APs of interest and one or more UEs connected to WLAN APs of interest may report measurement results according to a measurement configuration such as that described above. As an example of event triggering, measurements may be requested when the WLAN load exceeds a specified threshold. If the WLAN load is too low and little interference is present, reports may not be necessary, particularly if the maximum tolerable latency in the WLAN is not set too strictly. Such an approach allows a network to optimize the signaling load, taking into account the tradeoff between the number of reports, the number of triggered measurements, and the accuracy of measurements. 
         [0029]    A UE may report latency measurements using, for example. a long term evolution radio resource control (LTE RRC) measurement report. A suitably designed and configured AP is able to pass the report to the LTE network through a direct interface, such as a proprietary interface. operator backhaul, or other appropriate mechanisms. In one or more embodiments, the eNB and the AP may be elements or functions of the same physical structure, in which case communication between the eNB function and the WLAN function may be implemented as a part of the design of the structure. 
         [0030]    The eNB may collect packet queuing latency reports for uplink latency from one or more UEs connected to the same AP. and from the AP itself for downlink latency. At block  408 , the eNB may make decisions about WLAN offloading for current and upcoming bearers, with the decisions being based on the reported latency information. 
         [0031]      FIG. 5  illustrates a procedure  500  of packet queuing latency reporting by UEs, according to an embodiment of the present invention, illustrating various elements involved in the procedure and signal and data exchanges between the various elements. Latency reporting by UEs may suitably be performed for uplink latency, because appropriate measurements may be made by UEs. In addition, UEs are able to receive downlink latency information from an AP, An AP, for example, may broadcast latency information, or such latency information may be requested from an AP by a UE. 
         [0032]    The procedure  500  includes operations carried out by a wireless network  502 . embodied by one or more eNBs, a first UE  504 , a second UE  506 , and a WLAN AP  508 . The wireless network  502  may suitably be a 3GPP LTE network. 
         [0033]    The UEs  504  and  506  may be connected to the network  502 , and may perform communication  509  informing the network  502  that internetworking support is available, allowing for offloading of LTE traffic to WLAN. 
         [0000]    A first ongoing data connection  510  is established between the AP  508  and the first UE  504 , and a second ongoing data connection  512  is established between the AP  508  and the second UE  506 . The network  502 , may, for example, be represented by a single eNB in the vicinity of the AP  508  and the UEs  504  and  506 , and by other eNBs in the vicinity of other elements, The network  502  may make WLAN packet queuing latency requests  514  and  516  to the UEs  504  and  506 , respectively. The requests may come in the form of RRCConnectionReconfiguration messages, which may provide measurement configuration information, such as configuration of measurements as periodic or non-periodic, configuration of periodicity of periodic measurements, and definitions of triggering events for non-periodic measurements. The UEs  504  and  506  may return indications that the requests have been received and acted on. These indications may take the form of RRCConnectionReconfigurationComplete messages  518  and  520 . 
         [0034]    The UEs  504  and  506  may then report WLAN packet queuing latency results in a communication  522 , encompassing information exchange between each of the UEs  504  and  506 , and the network  502 . The WLAN packet queuing latency results may include uplink latency information measured by the UE itself, and may also include downlink communication which may be measured by the access point and delivered to the UE. 
         [0035]      FIG. 6  illustrates a procedure  600  of access point reporting according to one or more embodiments of the present invention. The procedure  600  may include operations performed by the network  502  and the AP  508 . The network  502  may transmit a WEAN packet queuing latency measurement request  624  to the AP  408 . As an example, transmission may be accomplished using X2 signaling. It will be recognized, however, that any suitable communication mechanism may be used. 
         [0036]    The AP  508  may respond by transmitting a WEAN packet queuing latency measurement acknowledgement  626  to the network  502 . As an example, the transmission may be accomplished using X2 signaling. The AP  508  may then perform a latency measurement  628  and may transmit a WLAN packet queuing latency measurement report  630  to the network  502 , As an example, transmission may be accomplished using X2 signaling to the network  502 . In addition, the AP  508  may transmit a WLAN packet queuing latency measurement report to one or more UEs such as the UEs  504  and  506 , which are then able to provide both uplink information based on their own measurements, and downlink reports based on the reports they have received from the AP  508 . As noted above, once a network, suitably represented by one or more eNBs determining whether to offload traffic receives measurement reports such as those described above, each eNB making such a determination makes an offloading decision based on the reports. Mechanisms for both uplink latency reporting and downlink latency reporting are described above, and numerous alternative or additional mechanisms for latency reporting may be employed. Depending on the particular network design and configuration, one or both of uplink and downlink reporting may be employed, and eNBs may make offloading decisions based on available reporting. Generally, offloading decisions will be more accurate if both uplink and downlink latency information is available, but if only uplink or downlink information is available, decisions may be made based on the available category of information. 
         [0037]    One or more embodiments of the invention also address mechanisms for latency determination that are designed to be carried out without a need for reporting by an AP and/or a UE. Such an approach can be accomplished using time stamps in radio link control packet data units (RLC PDU) which may be received in an uplink connection between the UE and the eNB. Switching may take place below the RLC, allowing LTE RLC packets to be delivered over WLAN radio. For example, for an acknowledge mode data (AMD) PDU, the PDU format with a time stamp may be as illustrated in  FIG. 7 . showing a PDU  700 , The latency can be determined by comparing the received time against the timestamp. 
         [0038]    Such an approach is also applicable to an interface between a WLAN AP and an LTE eNB, and in such a case, downlink latency information can also be obtained through this mechanism. 
         [0039]      FIG. 8  illustrates an exemplary user device  800  according to an embodiment of the present invention, configured to act, for example, as a device controlled by a user subscribing to a network such as the network  300  or the network  500 . The user device comprises a data processor  802  and memory  804 , with the memory  804  suitably storing data  806  and software  808 . The user device  800  further comprises a transmitter  810 , receiver  812 , and antenna  814 . The software  806  stored in memory  804  includes program instructions (software (SW)) that, when executed by the associated data processor  802 , enable the user device to operate in accordance with the exemplary embodiments of this invention. That is, the exemplary embodiments of this invention may be implemented at Least in part by computer software executable by the DP  802  of the, various electronic components illustrated here, with such components and similar components being deployed in whatever numbers, configurations, and arrangements are desired for the carrying out of the invention. Various embodiments of the invention may be carried out by hardware, or by a combination of software and hardware (and firmware). 
         [0040]      FIG. 8  also illustrates an exemplary wireless access point  820 , allowing communication by wireless communication devices which operated, for example, as part of a wireless local area network or a wireless cellular network. 
         [0041]    The access point  820  comprises a data processor  822  and memory  824 , with the memory  824  suitably storing data  826  and software  828 . The access point  820  further comprises a transmitter  830 . receiver  832 , and antenna  836 . The software  826  stored in memory  824  includes program instructions (software (SW)) that when executed by the associated data processor  822 , enable the access point to operate in accordance with the exemplary embodiments of this invention. That is, the exemplary embodiments of this invention may be implemented at least in part by computer software executable by the DP  822  of the various electronic components illustrated here, with such components and similar components being deployed in whatever numbers, configurations, and arrangements are desired for the carrying out of the invention. Various embodiments of the invention may be carried out by hardware, or by a combination of software and hardware (and firmware). 
         [0042]      FIG. 8  also illustrates an exemplary eNB  850 , allowing communication by wireless communication devices which operated, for example, as part of a wireless local area network or a wireless cellular network. 
         [0043]    The eNB  850  comprises a data processor  852  and memory  854 , with the memory  854  suitably storing data  856  and software  858 . The eNB  850  further comprises a transmitter  860 , receiver  862 , and antenna  866 . The software  866  stored in memory  864  includes program instructions (software (SW)) that, when executed by the associated data processor  862 , enable the eNB to operate in accordance with the exemplary embodiments of this invention. That is, the exemplary embodiments of this invention may be implemented at least in part by computer software executable by the DP  852  of the various electronic components illustrated here, with such components and similar components being deployed in whatever numbers, configurations, and arrangements are desired for the carrying out of the invention. Various embodiments of the invention may be carried out by hardware, or by a combination of software and hardware (and firmware). 
         [0044]    The various embodiments of the user device  800  can include, but are not limited to, cellular phones, personal digital assistants (PDAs) having wireless communication capabilities, portable computers having wireless communication capabilities, image capture devices such as digital cameras having wireless communication capabilities, gaming dev ices having wireless communication capabilities, music storage and playback appliances having ireless communication capabilities, Internet appliances permitting wireless Internet access and browsing, as well as portable units or terminals that incorporate combinations of such functions. 
         [0045]    In one or more embodiments, the access point  850  may provide means for receiving packet queuing latency information relating to data traffic between a user device and a wireless local area network access point and means for determining allocation of communication traffic to the wireless local area network access point based on the at least one packet queuing latency measurement. 
         [0046]    In one or more embodiments, one or more of the user device  800  and the access point  820  may provide means for configuring measurement of packet queuing latency between a user device and a wireless local area network access point and means for causing transmission of measurement information to a base station. 
         [0047]    The memories  804 ,  824 , and  854  may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor based memory devices, flash memory, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory. The data processors  802 ,  822 , and  852  may be of any type suitable to the local technical environment, and may include one or more of general purpose computers, special purpose computers. microprocessors, digital signal processors (DSPs) and processors based on multi-core processor architectures, as non-limiting examples. 
         [0048]    While various exemplary embodiments have been described above it should be appreciated that the practice of the invention is not limited to the exemplary embodiments shown and discussed here. Various modifications and adaptations to the foregoing exemplary embodiments of this invention may become apparent to those skilled in the relevant arts in view of the foregoing description. 
         [0049]    Further, some of the various features of the above non-limiting embodiments may be used to advantage without the corresponding use of other described features. 
         [0050]    The foregoing description should therefore be considered as merely illustrative of the principles, teachings and exemplary embodiments of this invention, and not in limitation thereof.