Patent Application
20170215209
The present application is related to contention-based random access procedures for call establishment, and in particular to a give preference to emergency calls in contention-based random access procedures to reduce latency when a collision occurs.
Mobile phones initiate a random access procedure first when attempting to place a call. If an access attempt fails, the phone will wait a random back off time according to a uniform distribution between 0 and a back off parameter value prior to starting the random access procedure again. When multiple devices are competing for network resources at the same time, the risk of collision increases. It may take several access attempts to get radio resource for an emergency call establishment, which can result in long delays.
A mobile device implemented method includes receiving a request at the mobile device from a user to make an emergency call over a network, attempting to place the emergency call via the mobile device, detecting a failure of random access attempt procedure for the emergency call by the mobile device, using a reduced back off parameter value as compared to a back off parameter value for a non-emergency call, and re-attempting the random access procedure for the emergency call via the mobile device as a function of the reduced back off parameter value.
A machine readable storage device has instructions for execution by a processor to cause the machine to perform operations. The operations include receiving a request to make an emergency call over a network, attempting to place the emergency call via a random access procedure, detecting a failure of placement of the emergency call, detecting a failure of a random access procedure for the emergency call, using a reduced back off parameter value as compared to a back off parameter value for a non-emergency call, and re-attempting the random access procedure as function of the reduced back off parameter value.
A device includes a processor and a transceiver coupled to the processor. A memory device is coupled to the processor and has a program stored thereon for execution by the processor to perform operations. The operations include receiving a request from a user to make an emergency call over a network, attempting to place the emergency call, detecting a failure of the random access procedure of the emergency call, using a reduced back off parameter value as compared to a back off parameter value for a non-emergency call, and re-attempting the random access procedure for the emergency call responsive to the reduced back off parameter value.
In the following description, reference is made to the accompanying drawings that form a part hereof, and in which is shown by way of illustration specific embodiments which may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized and that structural, logical and electrical changes may be made without departing from the scope of the present invention. The following description of example embodiments is, therefore, not to be taken in a limited sense, and the scope of the present invention is defined by the appended claims.
The functions or algorithms described herein may be implemented in software in one embodiment. The software may consist of computer executable instructions stored on computer readable media or computer readable storage device such as one or more non-transitory memories or other type of hardware based storage devices, either local or networked. Further, such functions correspond to modules, which may be software, hardware, firmware or any combination thereof. Multiple functions may be performed in one or more modules as desired, and the embodiments described are merely examples. The software may be executed on a digital signal processor, ASIC, microprocessor, or other type of processor operating on a computer system, such as a personal computer, server or other computer system, turning such computer system into a specifically programmed machine.
In various embodiments, preference is given to emergency calls in a contention based random access procedure to reduce the latency of user equipment (UE) emergency call at random access procedure phase and to improve emergency call establishment time. Example UEs include mobile phones and other wireless network connected devices. A back off time between access attempts by UE attempting to establish a call over a network is decreased for emergency calls, effectively giving emergency calls increased prioritization. Reducing the time between access attempts for emergency calls decreases latency for establishing emergency calls as compared to non-emergency calls, which are referred to as regular calls. In some embodiments, a larger maximum number of preamble transmissions is used as compared to the maximum number of preamble transmissions for a non-emergency call.
In some embodiments, the back off time is a selected random value between 0 and a back off parameter value. The back off parameter value for an emergency call may be referred to as a reduced back off parameter value. Using the reduced back off parameter value reduces the delay of subsequent random access attempt transmissions for emergency calls. Based on the number of access attempts that have failed, such as 2, 3, or more, the value of the reduced back off parameter may be increased until the value reaches the regular back off parameter value.
A maximum number of random access preamble transmissions may also be configurable in further embodiments. The maximum number of random access preamble transmissions may be set by a UE or a network, and may be increased for an emergency call compared to a corresponding parameter for regular calls. Modification of the maximum number of access attempts parameter may further increase the likelihood that an emergency call will be established.
In further embodiments, both parameters may be set by a network operator or an OEM (original equipment manufacturer) and the network can dynamically change the values while regular calls follow a current standard specification such as 3GPP (3rd Generation Partnership Project) and 3GPP2 (3rd Generation Partnership Project 2) and may apply to all radio access technology (RAT).
In still a further embodiment, based on a real time network condition, networks may provide a dedicated range of the back off parameter for emergency calls and optionally a larger time range that is dedicated for regular calls. If a large volume of emergency calls are occurring, such as due to a large fire or other large emergency being witnessed by many people, the back off parameter value for emergency calls may be increased towards or to the regular call back off parameter value.
In one embodiment, under certain network conditions, the network may also give emergency calls a specific back off parameter value range, and provide a different range for regular calls. The range can be dynamically changed by the network based on the network information and condition. The emergency call back-off parameter value range may be [0 to Ab], and the regular call back off parameter value range may be from (Ab, max_back_off_value]. The Ab may be the emergency back off parameter value.
The actual time between access attempts will be based on the random values, which will on average be less than the 10 ms and 960 ms back off times shown. Various contention based random access procedures are described in CDMA (code division multiple access), GSM (global system for mobile communications), WCDMA (Wideband CDMA), and LTE (long term evolution—3GPP 4G) RATs, and
Access attempts for regular calls 215 occur with a back off time of 960 ms in one embodiment and emergency calls 210 occur with a back off time of 10 ms. A first access attempt occurs when a user, such as a human, presses a button to dial a number as indicated at 220 and 225 for regular and emergency calls respectively. The time interval is referred to as a back off time. The time interval starts when a collision is detected responsive to an access attempt as indicated by lines 230 and 231 for regular calls and 235 and 236 for emergency calls. As represented in
The back off parameter value for emergency calls may be referred to as a reduced back off parameter value. The reduced back off parameter value in one embodiment is a value range to reduce the delay of subsequent random access attempt transmissions. Based on the number of access attempts that have failed, such as 2, 3, or more, the reduced back off parameter value may be increased until the value reaches the regular back off parameter value.
A maximum number of access attempts parameter may also be configurable in further embodiments. The maximum number of access attempts parameter may be set by the UE or network, and may be increased over a corresponding parameter for regular calls. Modification of the maximum number of access attempts parameter may further increase the likelihood that an emergency call will be established.
In further embodiments, both parameters may be set by UE or network, and the network can dynamically change the values while regular calls follow a current network standard specification such as 3GPP and 3GPP2 and may apply to all radio access technology (RAT).
In still a further embodiment, based on a real time network condition, networks may provide a dedicated range of the back off parameter for emergency calls and a larger time range that is dedicated for regular calls. Note that the term “range” refers to a randomization of the back off parameter that may be performed by the UE to reduce the chances that multiple UE will keep repeating attempts on a same schedule, increasing the chances of a collision. Thus, the term back off time parameter results in a random amount of Lime between additional access attempts. The range may be centered about the parameter in some embodiments, effectively being an average time between access attempts.
A call box, commonly referred to as a network emulator, may be configured to detect whether or not a reduced back off parameter is being used by a UE. The call box simply does not respond to attempts, causing the UE to continue access attempts. If the time between access attempts for emergency calls is shorter than the time between access attempts for regular calls, it can be determined that a shorter back off parameter is being used for emergency calls.
At 325, UE determines whether or not the call is an emergency call. Operation 315 may set a flag indicating the call is an emergency call in one embodiment, with operation 325 checking the flag to make the determination, or operation 325 may directly check the selected call number against the list of known emergency numbers in the location of the UE in order to make the determination. If the call is not an emergency call, a standard random access procedure is followed for non-emergency, regular, calls at 330.
If the call is determined to be an emergency call, the back off parameter value is set to a shorter value, referred to as for example, Tmax_e911 backoff. The emergency call back off parameter value may be set by the network or the UE in various embodiments. The back off parameter value may be very small, and gradually increased until the emergency call back off parameter value is the same as the regular call back off parameter value in some embodiments. The emergency call back off parameter value may be initially set to zero in some embodiments. In some embodiments, the max number of preamble transmissions is set to a larger number as compared to the maximum number of random access preamble transmissions for a non-emergency call, referred to as for example, Max-e911-attempts. The emergency call max number of random access preamble transmissions may be set by the network or the UE in various embodiments.
At 340, a random access resource is selected. The random access preamble is transmitted at 345.
At 350, a random access response is received and contains a random access preamble identifier (RAP ID). Operation 350 determines if the received RAP ID matches the RAP ID transmitted within a random access response window. If yes, a layer 2/layer 3 message is sent to 355, and an operation 360 determines if the received message for earlier contention resolution was received before a contention resolution time expires. If yes, the random access is successful at 365. A contention resolution timer may be used as a timer for contention resolution. If the UE does not receive the contention resolution message in this time frame, the UE will start to obtain an access resource again, essentially starting over. If the UE does not receive the random access response which contains a random access preamble identifier transmitted within a random access response window, method 300 proceeds to operation 370.
If the access is not successful, corresponding to the UE not receiving the earlier contention resolution within the contention resolution time, a preamble transmission count is increased by one at 370. In one embodiment, it is determined if the emergency call back off parameter value plus an increment, Δt, is less than or equal to the maximum back off parameter value for a regular call. If yes, Δt is added to Tmax_e911 backoff. Δt maybe set to 0 or a small value and it is configurable.
The method proceeds to operation 385 from either operation 380, or operation 375 if the back off parameter value plus an increment, Δt, is greater than the maximum back off parameter value for a regular call. At operation 385, the preamble transmission count is checked to determine whether it is still less than the maximum number of random access preamble transmissions, Max-e911-attempts. If not, an indication of the random access procedure failing is provided to upper protocol stack layers of the UE, at 390, such as a medium access control layer and a radio resource control layer. If yes, the method 300 waits until an emergency back off timer expires at 395, and the method continues at 340 to make another attempt to establish the call. The back off time is a selected random value between 0 and a back off parameter value.
Memory 404 may include volatile memory 406 and non-volatile memory 408. Computer 410 may include—or have access to a computing environment that includes—a variety of computer-readable media, such as volatile memory 406 and non-volatile memory 408, removable storage 412 and non-removable storage 414. Computer storage includes random access memory (RAM), read only memory (ROM), erasable programmable read-only memory (EPROM) & electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, compact disc read-only memory (CD ROM), Digital Versatile Disks (DVD) or other optical disk storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices capable of storing computer-readable instructions for execution to perform functions described herein.
Computer 410 may include or have access to a computing environment that includes input 416, output 416, and a communication connection 420. In one embodiment, the communication connection 420 is a transceiver coupled to an antenna and operable to communicate via a wireless network, such as a cellular network. Processing unit 104 may include multiple processors for executing code related to multiple different levels of a wireless protocol stack in accordance with one or more wireless standards to transmit and receive signals wirelessly via the communication connection. Output 418 may include a display device, such as a touchscreen, that also may serve as an input device. The input 416 may include one or more of a touchscreen, touchpad, mouse, keyboard, camera, one or more device-specific buttons, one or more sensors integrated within or coupled via wired or wireless data connections to the computer 410, and other input devices. The computer may operate in a networked environment using a communication connection to connect to one or more remote computers, such as database servers, including cloud based servers and storage. The remote computer may include a personal computer (PC), server, router, network PC, a peer device or other common network node, or the like. The communication connection may include a Local Area Network (LAN), a Wide Area Network (WAN), cellular, WiFi, Bluetooth, or other networks.
Computer-readable instructions stored on a computer-readable storage device are executable by the processing unit 402 of the computer 410. A hard drive, CD-ROM, and RAM are some examples of articles including a non-transitory computer-readable medium such as a storage device. The terms computer-readable medium and storage device do not include carrier waves. For example, a computer program 425 capable of providing a generic technique to perform access control check for data access and/or for doing an operation on one of the servers in a component object model (COM) based system may be included on a CD-ROM and loaded from the CD-ROM to a hard drive. The computer-readable instructions allow computer 410 to provide generic access controls in a COM based computer network system having multiple users and servers.
1. In example 1, a mobile device implemented method includes receiving a request at the mobile device from a user to make an emergency call over a network, attempting to place the emergency call via the mobile device, detecting a failure of a random access procedure for the emergency call by the mobile device, using a reduced back off parameter value as compared to a back off parameter value for a non-emergency call, and re-attempting the random access procedure for the emergency call via the mobile device as a function of the reduced back off parameter value.
2. The method of example 1 wherein the request to make an emergency call is detected as an emergency call by the mobile device comparing a phone number with known emergency call phone numbers.
3. The method of any of examples 1-2 wherein re-attempting the random access procedure is based on a network or mobile device configurable reduced back off parameter value.
4. The method of any of examples 1-3 and further comprising repeating re-attempting the emergency call random access procedure.
5. The method of example 4 wherein a maximum number of random access preamble transmissions to place the emergency call is higher than a maximum number of random access preamble transmissions for regular calls.
6. The method of any of examples 4-5 wherein the reduced back off parameter value is increased responsive to a number of access attempts until a non-emergency back off parameter value is reached.
7. The method of any of examples 1-5 wherein the reduced back off parameter value for emergency calls is configured by the mobile device or received by the mobile device from the network.
8. The method of example 7 wherein the back off parameter value for non-emergency calls is dynamically set by the network to a parameter value greater than or equal to the emergency call back off parameter and up to a maximum back off parameter value.
9. The method of example 7 wherein the back off parameter value for emergency calls is changed as a function of volume of emergency calls being placed by devices coupled to the network.
10. In example 10, a machine readable storage device has instructions for execution by a processor to cause the machine to perform operations including receiving a request to make an emergency call over a network, attempting to place the emergency call, detecting a failure of a random access procedure for the emergency call, using a reduced back off parameter value as compared to a back off parameter value for a non-emergency call, and re-attempting random access procedure as function of the reduced back off parameter value.
11. The machine readable storage device of example 10 wherein the request to make an emergency call is detected as an emergency call by comparing a phone number with known emergency call phone numbers.
12. The machine readable storage device of any of examples 10-11 and further comprising repeating the random access procedure for the emergency call.
13. The machine readable storage device of example 12 wherein a maximum number of random access preamble transmissions to place the emergency call is higher than a maximum number of random access preamble transmissions for regular calls.
14. The machine readable storage device of example 12 wherein the reduced back off parameter value is increased responsive to a number of access attempts until a non-emergency back off parameter value is reached.
15. The machine readable storage device of any of examples 10-14 wherein the reduced back off parameter value for emergency calls is configured by a mobile device or is received from the network.
16. The machine readable storage device of example 15 wherein the back off parameter value for non-emergency calls is dynamically set by the network to a parameter value greater than or equal to the emergency call back off parameter and up to a maximum back off parameter value.
17. The machine readable storage device of example 15 wherein the back off parameter value for emergency calls is changed as a function of a volume of emergency calls being placed by devices coupled to the network.
18. In example 18, a device includes a processor, a transceiver coupled to the processor, and a memory device coupled to the processor and having a program stored thereon for execution by the processor to perform operations. The operations include receiving a request from a user to make an emergency call over a network, attempting to place the emergency call, detecting a failure of a random access procedure of the emergency call, using a reduced back off parameter value as compared to a back off parameter value for a non-emergency call, and re-attempting random access procedure responsive to a reduced back off parameter value.
19. The device of example 18 wherein the request to make an emergency call is detected as an emergency call by comparing a phone number with known emergency call phone numbers.
20. The method of any of examples 18-19 and further comprising repeating the random access procedure to place the emergency call wherein a maximum number of random access preamble transmissions is higher than a maximum number of random access preamble transmission for regular calls.
Although a few embodiments have been described in detail above, other modifications are possible. For example, the logic flows depicted in the figures do not require the particular order shown, or sequential order, to achieve desirable results. Other steps may be provided, or steps may be eliminated, from the described flows, and other components may be added to, or removed from, the described systems. Other embodiments may be within the scope of the following claims.
