Abstract:
Systems and techniques for minimize drive testing measurements. Network elements including UEs and eNBs are configured to define measurement procedures to determine control plane latency affecting scheduling requests, RACH procedures, and combinations thereof. Upon initiation of a request for uplink resources, such as a scheduling request or a RACH procedure, a UE notes the time of the request and measures the time until its fulfillment. If a scheduling request fails, a RACH procedure may be performed and in such cases, the time from initiation of the scheduling request, through its failure, until successful completion of the RACH procedure may be measured. Once a measurement has been made, the measured duration and other associated information are assembled and analyzed, and when the measurement and other information meets criteria for inclusion in a measurement report, the report is assembled and sent, or logged for sending, to an eNB.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates generally to wireless communication. More particularly, the invention relates to improved systems and techniques for measurement of network conditions. 
       BACKGROUND 
       [0002]    Design and maintenance of wireless communication networks naturally involves testing of network conditions and refinement of network elements based on the network conditions. One approach is through drive testing—traveling through the network environment (for example, in a van equipped with test devices) and measure coverage and signal quality of the network in order to gather data that can be used to refine the network. Driving through a network environment and collecting measurements is naturally expensive and, in addition, adds at least somewhat to road traffic, noise, and pollution. Network operators have turned, as much as possible, to automated approaches, which have been defined by third generation partnership project (3GPP) standards relating to minimization of drive testing (MDT). User devices report network conditions, and these reports can be analyzed for the information they yield about network performance. Two reporting approaches have been defined—immediate reporting and logged reporting. With immediate mode MDT reporting, measurements are reported immediately after being performed. With logged MDT reporting, a user device is configured when in connected mode and takes measurements while in idle mode. Reports are sent to the network when the user device enters connected mode. 
       SUMMARY OF THE INVENTION 
       [0003]    This section contains examples of possible implementations and is not meant to be limiting. 
         [0004]    In one embodiment of the invention, an apparatus comprises memory, at least one processor, and a program of instructions. The memory storing the program of instructions is configured, with the at least one processor, to cause the apparatus to at least control a user device to note the time of a request from the user device of uplink transmission resources, control the user device to measure the elapsed time between the request for uplink transmission resources and fulfilment of the request, and assemble the measurement information for the elapsed time for inclusion in a measurement report to be transmitted to a network. 
         [0005]    In another embodiment of the invention, a method comprises controlling a user device to note the time of a request from the user device of uplink transmission resources, controlling the user device to measure the elapsed time between the request for uplink transmission resources and fulfilment of the request, and assembling the measurement information for the elapsed time for inclusion in a measurement report to be transmitted to a network. 
         [0006]    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 control a user device to note the time of a request from the user device of uplink transmission resources, control the user device to measure the elapsed time between the request for uplink transmission resources and fulfilment of the request, and assemble the measurement information for the elapsed time for inclusion in a measurement report to be transmitted to a network. 
         [0007]    In another embodiment of the invention, an apparatus comprises means for controlling a user device to note the time of a request from the user device of uplink transmission resources, means for controlling the user device to measure the elapsed time between the request for uplink transmission resources and fulfilment of the request, and means for assembling the measurement information for the elapsed time for inclusion in a measurement report to be transmitted to a network. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  illustrates a wireless network according to an embodiment of the present invention; 
           [0009]      FIG. 2  illustrates a process according to an embodiment of the present invention; and 
           [0010]      FIG. 3  illustrates elements used in carrying out one or more embodiments of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0011]    Various embodiments of the present invention address changing usage of wireless networks and changes in the importance of factors relating to network performance. Aspects of network performance include quality of service (measured by bit rate for non-guaranteed bit rate uses), radio link failure (RLF) and radio connection establishment failure (RCEF). 
         [0012]    Network usage is being dominated more and more by smartphones and other devices using data communication. Such devices often require an always online connection, in which a device communicates with the network (and, through the network, servers providing data) whether or not the user is actively using the device. Even in “idle” mode, then, a device may generate frequent, if small, data packets which have to be sent to the network, while also receiving such data packets from the network. With large numbers of data communication devices, such traffic may constitute a substantial portion of, or even most of, the communication over the network. Such traffic requires efficient operation for call setups and resource allocations. Traffic most characteristic of smartphone and similar data communication devices calls for short control plane (CP) delays, and delays in setting up for and achieving individual packet transfer connections has a negative influence on the end user experience of service quality. In one or more embodiments, the invention provides mechanisms to measure control plane latency and latency related to allocation of resources after a scheduling request. 
         [0013]      FIG. 1  illustrates a wireless network  100  comprising a plurality of base stations, which may be implemented in the form of  3 GPP evolved Node Bs (eNBs)  102 A- 102 C, defining cells  104 A- 104 C, respectively. The network  100  supports user devices, implemented in the form of 3GPP user equipments (UEs),  106 A- 106 C. The UEs may be used to take and report measurements of specified conditions, and these measurements can be used to compute information relating to network performance. The network performance information, and the measurements and measurement location can be used to determine adjustments to network parameters to improve performance. 
         [0014]    Specifically, one or more embodiments of the invention provide mechanisms and define procedures for measurements of control plane latency and latency related to the time between a scheduling request is made and resources are allocated to fulfill the scheduling request. 
         [0015]    In one or more embodiments of the invention, therefore, a network implements mechanisms allowing a UE to measure the time it takes to be allocated resources and to report those measurements to its serving eNB.  FIG. 2  illustrates a process  200  of latency measurement according to an embodiment of the present invention. The process  200  may be performed in an ongoing fashion, with a number of alternative approaches to latency measurement being taken. 
         [0016]    At block  202 , one or more UEs are configured to perform MDT measurements that include latency measurements. The configuration specifies the measurements to be taken under various conditions, and the information collected for delivery to the eNB. Conditions include, for example, whether it is possible to send a scheduling request (SR) on the physical uplink control channel (PUCCH). The configuration may specify the mechanisms for latency measurement, and may specify different latency measurements depending on (for example) whether a scheduling request is sent or a random access channel (RACH) procedure is followed. Information to be collected may be the number of scheduling requests that were sent, whether the maximum number of scheduling requests was sent, contention procedure results, counters, and other details of the prevailing conditions and the taking of the measurements. 
         [0017]    At block  203 , a UE recognizes that uplink data for a logical channel has become available for transmission in an RLC entity or in a PDCP entity, and this recognition triggers a buffer status report. Suppose that the buffer status report indicates that no resources are available. The process then proceeds to block  204  and the UE proceeds to seek allocation of resources, first determining if a scheduling request can be sent on the physical uplink control channel (PUCCH). 
         [0018]    At block  204 , then, the UE initiates scheduling request procedures—noting that it has data to transmit and that no other scheduling request is in progress. The UE sets the scheduling request counter to zero and determines if the physical uplink control channel is configured for a scheduling request and is otherwise available. If the physical uplink control channel is not configured for a scheduling request or is otherwise unavailable, the process skips to step  250  and a random access channel procedure is initiated. Reasons for unavailability of the physical access control channel might be that the timing advance timer (TAT) has expired, so that uplink synchronization has been lost. If the physical uplink control channel is configured for a scheduling request, the process proceeds to block  206  and the UE undertakes procedures for generating and sending the scheduling request—determining whether the state is Measurement GAP, whether the scheduling request prohibition timer sr-ProhibitTimer is running, and whether the value of SR Counter is less than dsr-TransMax, with the UE incrementing the SR_Counter and sending the scheduling request if all of the required conditions are met, and also starting the scheduling request prohibition timer sr-ProhibitTimer. 
         [0019]    At block  208 , the UE determines whether SR_Counter has reached a maximum value. If so, the process skips to block  250  and a random access procedure is begun. If the SR_Counter is not at a maximum value, the process proceeds to block  210  and the UE notes the time transmission interval (TTI) at which the scheduling request is sent. At block  212 , the UE waits for the uplink grant. If the request times out, the process branches back to block  206 . 
         [0020]    Once the base station has returned an uplink grant, the process proceeds to step  214  and the interval that has elapsed since sending of the first attempt at a scheduling request is evaluated and measurement information is created identifying the scheduling request and including the value of the latency interval. The measurement entry may include, for example, the SR_Counter value, and an indication of whether the dsr-TransMax value has been reached. The process then proceeds to block  256 . 
         [0021]    At block  250 , a random access channel procedure is initiated. The random access channel procedure may come as a result of failure to initiate or failure to complete a scheduling request procedure, because the UE is not configured to perform a scheduling request procedure at one time or another, because the UE alternates between scheduling request and random access channel procedures, or for any other suitable reason. It will be recognized that performing a scheduling request procedure and performing a random access channel procedure need not be done sequentially, but that the presentation here is simply for convenience in illustrating procedures that may be performed and latency measurements taken. 
         [0022]    At block  252 , a random access preamble is sent over a random access channel and the value of PREAMBLE_TRANSMISSION COUNTER is initiated or incremented, depending on whether an attempt is being initiated or continued after a timeout or failure, and the transmission time interval at which the preamble is sent is noted. Other timers relating to the procedure are initiated, such as the mac-ContentionResolutionTirner, if a contention-based RACH procedure is being used. At block  254 , the UE monitors events in order to recognize an indication of successful conclusion of the RACH procedure and notes the elapsed time from the transmission time interval marking the beginning of the attempt to obtain an uplink grant. If the RACH procedure was performed as a result of a failed or timed out scheduling request procedure, the elapsed time will include the time from the sending of the scheduling request. 
         [0023]    At block  256 , data is assembled for potential inclusion in a measurement report. Data includes the latency interval and may also include additional elements—for example, the value of SR_COUNTER, an indication of whether or not dsr-TransMax was reached, the value of mac-ContentionResolutionTimer (if a random access procedure was performed), and the value of PREAMBLE_TRANSMISSION_COUNTER. The measurement may also include the value of the T 300  radio resource control (RRC) connection timer for a successful connection establishment request, as well as an indicator to distinguish resource requests made in connected mode from those made in idle mode. The measurement may also include an indicator showing whether scheduling request or a RACH procedure was used, or whether both a scheduling request and a RACH procedure were used (indicating that a RACH procedure was used after failure of a scheduling request). 
         [0024]    At block  258 , the assembled data is analyzed and prepared for inclusion in a measurement report to be sent to an eNB or other suitable network element. Measurement reports may, for example, be limited to measurements exceeding a predefined threshold or meeting other criteria, with the criteria being configured by radio resource control. In addition, as noted above, a reporting configuration may be used to indicate parameters to be included in the report. The configuration may be signaled to the UE. At block  260 D, data meeting criteria for inclusion in a measurement report is assembled into the report and, depending on whether MDT is being performed in immediate mode or logged mode, immediately transmitted to the UE or stored for later transmission. While latency measurements are discussed here for simplicity, it is also possible to collect additional information, such as quality of service information and radio link failure information, and include this information in the same measurement report as latency information. 
         [0025]      FIG. 3  illustrates details of a base station, implemented as an eNB  300 , and a mobile communication device, implemented as user device or UE  350 . The eNB  300  may suitably comprise a transmitter  302 , receiver  304 , and antenna  306 . The eNB  300  may also include a processor  308  and memory  310 . The eNB  300  may employ data  312  and programs (PROGS)  314 , residing in memory  310 . 
         [0026]    The UE  350  may suitably comprise a transmitter  352 , receiver  354 , and antenna  356 . The UE  350  may also include a processor  358  and memory  360 . The UE  350  may employ data  362  and programs (PROGS)  364 , residing in memory  360 . 
         [0027]    At least one of the PROGs  314  in the eNB  300  is assumed to include a set of program instructions that, when executed by the associated DP  308 , enable the device to operate in accordance with the exemplary embodiments of this invention, as detailed above. In these regards the exemplary embodiments of this invention may be implemented at least in part by computer software stored on the MEM  310 , which is executable by the DP  308  of the eNB  300 , or by hardware, or by a combination of tangibly stored software and hardware (and tangibly stored firmware). Similarly, at least one of the PROGs  364  in the UE  350  is assumed to include a set of program instructions that, when executed by the associated DP  358 , enable the device to operate in accordance with the exemplary embodiments of this invention, as detailed above. In these regards the exemplary embodiments of this invention may be implemented at least in part by computer software stored on the MEM  360 , which is executable by the DP  358  of the UE  350 , or by hardware, or by a combination of tangibly stored software and hardware (and tangibly stored firmware). Electronic devices implementing these aspects of the invention need not be the entire devices as depicted at  FIG. 1  or  FIG. 3  or may be one or more components of same such as the above described tangibly stored software, hardware, firmware and DP, or a system on a chip SOC or an application specific integrated circuit ASIC. 
         [0028]    In general, the various embodiments of the UE  350  can include, but are not limited to personal portable digital devices having wireless communication capabilities, including but not limited to cellular telephones, navigation devices, laptop/palmtop/tablet computers, digital cameras and music devices, and Internet appliances. 
         [0029]    Various embodiments of the computer readable MEM  310  and  360  include any data storage technology type which is suitable to the local technical environment, including but not limited to semiconductor based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory, removable memory, disc memory, flash memory, DRAM, SRAM, EEPROM and the like. Various embodiments of the DP  308  and  358  include but are not limited to general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and multi-core processors. 
         [0030]    Electronic devices implementing these aspects of the invention need not be the entire devices as depicted at  FIG. 1  or  FIG. 3  or may be one or more components of same such as the above described tangibly stored software, hardware, firmware and DP, or a system on a chip SOC or an application specific integrated circuit ASIC. 
         [0031]    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. 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. 
         [0032]    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. 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.