Providing a time offset between scheduling request and sounding reference symbol transmissions

A user equipment (UE) including a processor configured to promote scheduling transmission of a series of scheduling requests offset a series of sounding reference symbols.

BACKGROUND

Easily transportable devices with wireless telecommunications capabilities, such as mobile telephones, personal digital assistants, handheld computers, and similar devices, will be referred to herein as user equipment (UE). The term “UE” may refer to a device and its associated Universal Integrated Circuit Card (UICC) that includes a Subscriber Identity Module (SIM) application, a Universal Subscriber Identity Module (USIM) application, or a Removable User Identity Module (R-UIM) application or may refer to the device itself without such a card. The term “UE” may also refer to devices that have similar capabilities but that are not transportable, such as a desktop computer or a set-top box. A connection between a UE and some other element in a telecommunications network might promote a voice call, a file transfer, or some other type of data exchange, any of which can be referred to as a call or a session.

As telecommunications technology has evolved, more advanced network access equipment has been introduced that can provide services that were not possible previously. This advanced network access equipment might include, for example, an enhanced node B (ENB) rather than a base station or other systems and devices that are more highly evolved than the equivalent equipment in a traditional wireless telecommunications system. Such advanced or next generation equipment may be referred to herein as long-term evolution (LTE) equipment.

Some UEs have the capability to communicate in a packet switched mode, wherein a data stream representing a portion of a call or session is divided into packets that are given unique identifiers. The packets might then be transmitted from a source to a destination along different paths and might arrive at the destination at different times. Upon reaching the destination, the packets are reassembled into their original sequence based on the identifiers.

A signal that carries data between a UE and an ENB can have a specific set of frequency, code, and time parameters and other characteristics that might be specified by the ENB. A connection between a UE and an ENB that has a specific set of such characteristics can be referred to as a resource. An ENB typically establishes a different resource for each UE with which it is communicating at any particular time.

DETAILED DESCRIPTION

In an embodiment, a user equipment (UE) is provided that includes a processor configured to promote scheduling transmission of a series of scheduling requests offset a series of sounding reference symbols.

In another embodiment, a method is provided for a user equipment to transmit a series of periodic scheduling requests and a series of periodic sounding reference symbols. The method includes transmitting one of either the series of periodic scheduling requests or the series of periodic sounding reference symbols. The method includes offset transmitting the other of the series of periodic scheduling requests or the series of periodic sounding reference symbols.

In another embodiment, a component in a telecommunications network is provided. The component includes a processor configured to promote assigning a first resource for a series of periodic scheduling requests and assigning a second resource for a series of periodic sounding reference symbols scheduled to promote a user equipment transmitting the series of periodic scheduling requests and series of periodic sounding reference symbols offset to one another.

In one embodiment, a method is provided that includes assigning a first resource for a series of periodic scheduling requests, and assigning a second resource for a series of periodic sounding reference symbols scheduled. The first and second resource assigned to promote a user equipment (UE) transmitting the series of periodic scheduling requests and series of periodic sounding reference symbols offset to one another.

A four-step process might be followed in allocating an uplink resource to a UE so that the UE can transmit data to an ENB. In the first step, the UE sends a scheduling request (SR) to the ENB over an SR channel. The SR channel is a dedicated channel between the UE and the ENB that is traditionally established specifically for the purpose of providing the UE a channel for requesting resources from the ENB. In the second step, upon receiving the SR from the UE, the ENB assigns the UE a minimal amount of resource capacity. In the third step, the UE uses this limited resource capacity to send the ENB a buffer status report that informs the ENB of the quantity of data the UE wishes to send as well as other information such as QoS (Quality of Service) information. The ENB uses this information to determine the quantity of resource capacity the UE will need for the data the UE wishes to send. In the fourth step, the ENB allocates to the UE the amount of resource capacity appropriate for the data quantity and any QoS requirements or other considerations specified in the buffer status report. This resource capacity is then allocated for subsequent data packets that the UE transmits to the ENB.

To allow the UE have the capability to quickly request the uplink resource for the uplink transmission without any contentions, a periodical dedicated resource is allocated to the UE to transmit the scheduling request indicator (for example, every 20 ms). Whenever the UE has the buffered data to be transmitted on the uplink, UE should send the scheduling request indicator to the eNB.

A sounding reference symbol (SRS) is a reference tone (or reference symbol) that can be transmitted in an uplink from the UE to the ENB. The ENB measures the SRS to estimate the quality of the uplink channel so that uplink data transmissions can use a suitable modulation and coding scheme. Like the SR, the SRS might be transmitted from the UE to the ENB at periodic intervals.

The ENB assigns the UE different resources for the SR transmissions and the SRS transmissions, and the UE then transmits the SR on one of the resources and the SRS on the other resource. However, due to physical layer limitations, if the two transmissions happen to occur in the same sub-frame, the quality of the transmissions may be inadequate. To prevent unacceptable quality in an SR transmission, it has been proposed that if an SR transmission and an SRS transmission occur in the same sub-frame, the SRS transmission should be dropped.

This is illustrated inFIG. 1, where an SRS resource110includes a series of periodic SRS transmissions115from a UE10to an ENB20. In this example, the SRS transmissions115occur every 10 milliseconds, but other transmission periods could be used. Also shown is an SR resource120that includes a series of periodic SR transmissions125from the UE10to the ENB20. The SR transmissions125have a period of 30 milliseconds in this example, but could have a different period. Since the period of the SR transmissions125is an exact multiple of the period of the SRS transmissions115, and since the SRS transmissions115and the SR transmissions125begin at the same time, the two transmissions can periodically occur at substantially the same time. More specifically, in this example, every third SRS transmission115coincides with one of the SR transmissions125, as indicated by the dashed lines. The overlapping SRS transmissions115, namely SRS transmission115a, SRS transmission115d, and SRS transmission115g, would be dropped under the current proposals.

However, dropping an SRS transmission could prevent the ENB20from making a valid estimate of the uplink channel quality, which could lead to the use of a modulation and coding scheme that is more conservative or more aggressive than is appropriate. In an embodiment, an offset is introduced between the transmission times of a series of SR transmissions and a series of SRS transmissions to reduce, and in some cases eliminate, the possibility that an SR transmission and an SRS transmission will occur in the same sub-frame. That is, the ENB20assigns the SRS resource110and the SR resource120in such a manner that when the first transmission occurs on one of the resources, a short delay occurs before a transmission occurs on the other resource. Subsequent transmissions then occur on both resources with the periods the transmissions would otherwise have had. This causes the same offset to be present between the transmissions and can prevent an SRS transmission and an SR transmission from occurring in the same sub-frame. This, in turn, can prevent the dropping of an SRS transmission and allow both transmissions to occur with sufficient quality. In some embodiments, the time offset is applied to the SR transmissions and in other embodiments the offset is applied to the SRS transmissions. As an example, the offset might be approximately 1 millisecond.

Such an offset could be applied in four different situations. In a general case, there is no regular relationship between the period of the SR transmissions and the period of the SRS transmissions. In three special cases, the period of one of the transmissions is a whole multiple of the period of the other transmission. The first of these special cases is similar to the scenario ofFIG. 1, where the period of the SR transmissions125is a whole multiple of the period of the SRS transmissions115. In a second special case, the period of the SRS transmissions is a whole multiple of the period of the SR transmissions. In a third special case, the periods of the SRS transmissions and the SR transmissions are equal.

FIG. 2illustrates an embodiment where the SR and the SRS are not transmitted with frequencies where the period of one set of transmissions is a whole multiple of the other. In this example, the SRS resource110might include a series of SRS transmissions210that have a period of 10 milliseconds, and the SR resource120might include a series of SR transmissions220that have a period of 13 milliseconds. In other cases, the transmissions could have other non-multiple periods.

In an embodiment, a small offset290is introduced into the transmission times of the SR transmissions220. That is, the first SR transmission220abegins a short time after the first SRS transmission210a. Thereafter, the SRS transmissions210and the SR transmissions220continue with their usual periods of 10 milliseconds and 13 milliseconds, respectively. In other embodiments, the offset290could be applied to the transmission times of the SRS transmissions210rather than the SR transmissions220. Dashed lines indicate the times when the SRS transmissions210occur. It can be seen that none of the SR transmissions220overlap with the SRS transmissions210in this case. Therefore, none of the SRS transmissions210will be dropped.

The offset290can reduce the likelihood that the SRS transmissions210and the SR transmissions220will occur in the same sub-frame. However, in this general case, overlaps could still occur for certain combinations of SRS periods, SR periods, and sizes of the offset290. For example, if the SRS transmissions210have a period of 20 milliseconds, the SR transmissions220have a period of 30 milliseconds, and the offset290is 10 milliseconds, an overlap between the SRS transmissions210and the SR transmissions220will occur every 60 milliseconds.

For the three special cases where one of the periods is a whole multiple of the other, the size of the offset290can be chosen such that overlaps do not occur. One of these special cases is illustrated inFIG. 3, where the period of a series of SR transmissions240is a whole multiple of the period of a series of SRS transmissions230. In this example, the SRS transmissions230have a period of 10 milliseconds and the SR transmissions240have a period of 30 milliseconds. An instance of the offset290has been introduced into the SR transmissions240in this example. In other embodiments, the offset290could be placed in the SRS transmissions230.

After the offset290is applied, the SR transmissions240continue with a period of 30 milliseconds, causing the same offset290to be applied to the subsequent SR transmissions240. Dashed lines indicate the times when the SRS transmissions230occur and when the SR transmissions240might have occurred if the SR transmissions240did not have the offset290. It can be seen that with an appropriate choice for the size of the offset290, the SRS transmissions230and the SR transmissions240will never overlap. For example, as long as the size of the offset290is not a whole multiple of the period of the SRS transmissions230, the SRS transmissions230and the SR transmissions240will not coincide and no SRS transmissions230will be dropped.

Another of the special cases is illustrated inFIG. 4. In this case, the period of a series of SRS transmissions250is a whole multiple of the period of a series of SR transmissions260. An instance of the offset290has been applied to the SR transmissions260in this example, but in other embodiments, the offset290could be placed in the SRS transmissions250. Dashed lines again indicate the times when the SRS transmissions250occur and when the SR transmissions260might have occurred without the offset290. An appropriate size of the offset290can again ensure that the SRS transmissions250and the SR transmissions260will not coincide.

The third of the special cases is illustrated inFIG. 5. In this case, the period of a series of SRS transmissions270is equal to the period of a series of SR transmissions280. An instance of the offset290has been applied to the SR transmissions280in this example, but in other embodiments, the offset290could be applied to the SRS transmissions270. Dashed lines indicate the times when the SRS transmissions270occur and when the SR transmissions280would have occurred without the offset290. With an appropriate size of the offset290, the SRS transmissions270and the SR transmissions280will again not coincide.

FIG. 6Aillustrates an embodiment of a method300for transmitting a series of periodic scheduling requests and a series of periodic sounding reference symbols. In block310, the method provides for transmitting one of either the series of periodic scheduling requests or the series of periodic sounding reference symbols. In block320, the method includes offset transmitting the other of the series of periodic scheduling requests or the series of periodic sounding reference symbols.

FIG. 6Billustrates another method350for assigning resources. The method includes, in block352, assigning a first resource for a series of periodic scheduling requests. In block354, the method provides for assigning a second resource for a series of periodic sounding reference symbols. The first and second resources assigned to promote a user equipment (UE) transmitting the series of periodic scheduling requests and series of periodic sounding reference symbols offset to one another.

FIG. 7illustrates a wireless communications system including an embodiment of the UE10. The UE10is operable for implementing aspects of the disclosure, but the disclosure should not be limited to these implementations. Though illustrated as a mobile phone, the UE10may take various forms including a wireless handset, a pager, a personal digital assistant (PDA), a portable computer, a tablet computer, or a laptop computer. Many suitable devices combine some or all of these functions. In some embodiments of the disclosure, the UE10is not a general purpose computing device like a portable, laptop or tablet computer, but rather is a special-purpose communications device such as a mobile phone, a wireless handset, a pager, a PDA, or a telecommunications device installed in a vehicle. In another embodiment, the UE10may be a portable, laptop or other computing device. The UE10may support specialized activities such as gaming, inventory control, job control, and/or task management functions, and so on.

The UE10includes a display402. The UE10also includes a touch-sensitive surface, a keyboard or other input keys generally referred as404for input by a user. The keyboard may be a full or reduced alphanumeric keyboard such as QWERTY, Dvorak, AZERTY, and sequential types, or a traditional numeric keypad with alphabet letters associated with a telephone keypad. The input keys may include a trackwheel, an exit or escape key, a trackball, and other navigational or functional keys, which may be inwardly depressed to provide further input function. The UE10may present options for the user to select, controls for the user to actuate, and/or cursors or other indicators for the user to direct.

The UE10may further accept data entry from the user, including numbers to dial or various parameter values for configuring the operation of the UE10. The UE10may further execute one or more software or firmware applications in response to user commands. These applications may configure the UE10to perform various customized functions in response to user interaction. Additionally, the UE10may be programmed and/or configured over-the-air, for example from a wireless base station, a wireless access point, or a peer UE10.

Among the various applications executable by the UE10are a web browser, which enables the display402to show a web page. The web page may be obtained via wireless communications with a wireless network access node, a cell tower, a peer UE10, or any other wireless communication network or system400. The network400is coupled to a wired network408, such as the Internet. Via the wireless link and the wired network, the UE10has access to information on various servers, such as a server410. The server410may provide content that may be shown on the display402. Alternately, the UE10may access the network400through a peer UE10acting as an intermediary, in a relay type or hop type of connection.

FIG. 8shows a block diagram of the UE10. While a variety of known components of UEs10are depicted, in an embodiment a subset of the listed components and/or additional components not listed may be included in the UE10. The UE10includes a digital signal processor (DSP)502and a memory504. As shown, the UE10may further include an antenna and front end unit506, a radio frequency (RF) transceiver508, an analog baseband processing unit510, a microphone512, an earpiece speaker514, a headset port516, an input/output interface518, a removable memory card520, a universal serial bus (USB) port522, a short range wireless communication sub-system524, an alert526, a keypad528, a liquid crystal display (LCD), which may include a touch sensitive surface530, an LCD controller532, a charge-coupled device (CCD) camera534, a camera controller536, and a global positioning system (GPS) sensor538. In an embodiment, the UE10may include another kind of display that does not provide a touch sensitive screen. In an embodiment, the DSP502may communicate directly with the memory504without passing through the input/output interface518.

The antenna and front end unit506may be provided to convert between wireless signals and electrical signals, enabling the UE10to send and receive information from a cellular network or some other available wireless communications network or from a peer UE10. In an embodiment, the antenna and front end unit506may include multiple antennas to support beam forming and/or multiple input multiple output (MIMO) operations. As is known to those skilled in the art, MIMO operations may provide spatial diversity which can be used to overcome difficult channel conditions and/or increase channel throughput. The antenna and front end unit506may include antenna tuning and/or impedance matching components, RF power amplifiers, and/or low noise amplifiers.

The RF transceiver508provides frequency shifting, converting received RF signals to baseband and converting baseband transmit signals to RF. In some descriptions a radio transceiver or RF transceiver may be understood to include other signal processing functionality such as modulation/demodulation, coding/decoding, interleaving/deinterleaving, spreading/despreading, inverse fast Fourier transforming (IFFT)/fast Fourier transforming (FFT), cyclic prefix appending/removal, and other signal processing functions. For the purposes of clarity, the description here separates the description of this signal processing from the RF and/or radio stage and conceptually allocates that signal processing to the analog baseband processing unit510and/or the DSP502or other central processing unit. In some embodiments, the RF Transceiver508, portions of the Antenna and Front End506, and the analog baseband processing unit510may be combined in one or more processing units and/or application specific integrated circuits (ASICs).

The analog baseband processing unit510may provide various analog processing of inputs and outputs, for example analog processing of inputs from the microphone512and the headset516and outputs to the earpiece514and the headset516. To that end, the analog baseband processing unit510may have ports for connecting to the built-in microphone512and the earpiece speaker514that enable the UE10to be used as a cell phone. The analog baseband processing unit510may further include a port for connecting to a headset or other hands-free microphone and speaker configuration. The analog baseband processing unit510may provide digital-to-analog conversion in one signal direction and analog-to-digital conversion in the opposing signal direction. In some embodiments, at least some of the functionality of the analog baseband processing unit510may be provided by digital processing components, for example by the DSP502or by other central processing units.

The DSP502may communicate with a wireless network via the analog baseband processing unit510. In some embodiments, the communication may provide Internet connectivity, enabling a user to gain access to content on the Internet and to send and receive e-mail or text messages. The input/output interface518interconnects the DSP502and various memories and interfaces. The memory504and the removable memory card520may provide software and data to configure the operation of the DSP502. Among the interfaces may be the USB interface522and the short range wireless communication sub-system524. The USB interface522may be used to charge the UE10and may also enable the UE10to function as a peripheral device to exchange information with a personal computer or other computer system. The short range wireless communication sub-system524may include an infrared port, a Bluetooth interface, an IEEE 802.11 compliant wireless interface, or any other short range wireless communication sub-system, which may enable the UE10to communicate wirelessly with other nearby mobile devices and/or wireless base stations.

The input/output interface518may further connect the DSP502to the alert526that, when triggered, causes the UE10to provide a notice to the user, for example, by ringing, playing a melody, or vibrating. The alert526may serve as a mechanism for alerting the user to any of various events such as an incoming call, a new text message, and an appointment reminder by silently vibrating, or by playing a specific pre-assigned melody for a particular caller.

The keypad528couples to the DSP502via the interface518to provide one mechanism for the user to make selections, enter information, and otherwise provide input to the UE10. The keyboard528may be a full or reduced alphanumeric keyboard such as QWERTY, Dvorak, AZERTY and sequential types, or a traditional numeric keypad with alphabet letters associated with a telephone keypad. The input keys may include a trackwheel, an exit or escape key, a trackball, and other navigational or functional keys, which may be inwardly depressed to provide further input function. Another input mechanism may be the LCD530, which may include touch screen capability and also display text and/or graphics to the user. The LCD controller532couples the DSP502to the LCD530.

The CCD camera534, if equipped, enables the UE10to take digital pictures. The DSP502communicates with the CCD camera534via the camera controller536. In another embodiment, a camera operating according to a technology other than Charge Coupled Device cameras may be employed. The GPS sensor538is coupled to the DSP502to decode global positioning system signals, thereby enabling the UE10to determine its position. Various other peripherals may also be included to provide additional functions, e.g., radio and television reception.

FIG. 9illustrates a software environment602that may be implemented by the DSP502. The DSP502executes operating system drivers604that provide a platform from which the rest of the software operates. The operating system drivers604provide drivers for the wireless device hardware with standardized interfaces that are accessible to application software. The operating system drivers604include application management services (“AMS”)606that transfer control between applications running on the UE10. Also shown inFIG. 9are a web browser application608, a media player application610, and Java applets612. The web browser application608configures the UE10to operate as a web browser, allowing a user to enter information into forms and select links to retrieve and view web pages. The media player application610configures the UE10to retrieve and play audio or audiovisual media. The Java applets612configure the UE10to provide games, utilities, and other functionality. A component614might perform functions related to time offsets between SR and SRS transmissions.

The system described above may be implemented on any general-purpose computer with sufficient processing power, memory resources, and network throughput capability to handle the necessary workload placed upon it.FIG. 10illustrates a typical, general-purpose computer system suitable for implementing one or more embodiments disclosed herein. The computer system1300includes a processor1332(which may be referred to as a central processor unit or CPU) that is in communication with memory devices including secondary storage1338, read only memory (ROM)1336, random access memory (RAM)1334, input/output (I/O) devices1340, and network connectivity devices1312. The processor1332may be implemented as one or more CPU chips.

The secondary storage1338is typically comprised of one or more disk drives or tape drives and is used for non-volatile storage of data and as an over-flow data storage device if RAM1334is not large enough to hold all working data. Secondary storage1338may be used to store programs which are loaded into RAM1334when such programs are selected for execution. The ROM1336is used to store instructions and perhaps data which are read during program execution. ROM1336is a non-volatile memory device which typically has a small memory capacity relative to the larger memory capacity of secondary storage. The RAM1334is used to store volatile data and perhaps to store instructions. Access to both ROM1336and RAM1334is typically faster than to secondary storage1338.

The network connectivity devices1312may take the form of modems, modem banks, ethernet cards, universal serial bus (USB) interface cards, serial interfaces, token ring cards, fiber distributed data interface (FDDI) cards, wireless local area network (WLAN) cards, radio transceiver cards such as code division multiple access (CDMA) and/or global system for mobile communications (GSM) radio transceiver cards, and other well-known network devices. These network connectivity devices1312may enable the processor1332to communicate with an Internet or one or more intranets. With such a network connection, it is contemplated that the processor1332might receive information from the network, or might output information to the network in the course of performing the above-described method steps. Such information, which is often represented as a sequence of instructions to be executed using the processor1332, may be received from and outputted to the network, for example, in the form of a computer data signal embodied in a carrier wave. The network connectivity devices1312may also include one or more transmitter and receivers for wirelessly or otherwise transmitting and receiving signal as are well know to one of ordinary skill in the art.

The processor1332executes instructions, codes, computer programs, scripts which it accesses from hard disk, floppy disk, optical disk (these various disk based systems may all be considered secondary storage1338), ROM1336, RAM1334, or the network connectivity devices1312. While only one processor1332is shown, multiple processors may be present. Thus, while instructions may be discussed as executed by a processor, the instructions may be executed simultaneously, serially, or otherwise executed by one or multiple processors.

The following are incorporated herein by reference for all purposes: 3rdGeneration Partnership Project (3GPP) Technical Specification (TS) 36.300, 3GPP TS 36.321.