GB2502014A

GB2502014A - Reselecting a different transmission time interval resource in a wireless network

Info

Publication number: GB2502014A
Application number: GB1314651.9A
Authority: GB
Inventors: Brian Alexander Martin; Keiichi Kubota
Original assignee: Renesas Mobile Corp
Current assignee: Renesas Electronics Corp
Priority date: 2011-11-07
Filing date: 2011-11-07
Publication date: 2013-11-13
Also published as: GB201314651D0

Abstract

A mobile terminal selects a first TTI (Transmission Time Interval) resource in conjunction with an uplink (40). If a failure condition (44) associated with the uplink (42) is detected then a second TTI resource, different from the first TTI resource, is selected. The first and second TTI resource may define time periods of 2ms and 10ms respectively. The failure condition may be a transmission power level increasing above a threshold, a predefined number of retransmissions before a successful acknowledgement, detection of an unrecoverable error in the uplink or, failing to receive a response from a network to a transition indication (between the first and second TTI). The failure condition may be caused by a mobile terminal moving to a different portion of the coverage area and/or in an instance in which the TTI resource was initially incorrectly selected, such as based upon an inaccurate measurement.

Description

METHOD, APPARATUS AND COMPUTER PROGRAM FOR

RESELECTING A DIFFERENT TRANSMISSION TIME INTERVAL RESOURCE

Technical Field

S The present invention relates to a method, apparatus and computer program for reselecting a different transmission time interval (TTI) resource.

Background

Thc communications bctwccn a mobilc tcrminal and a scrving cdl, such as thc upliiil (UL) communications from the mobile terminal to the serving cell, may sometimes affect resource utilisation, throughput, latency and coverage. To enhance IJL improvements, the ongoing evolution of wireless communications systems such as, for example, the enhanced dedicated channel (E-DCH) in CELL FACH state feature was introduced into wireless standard specifications, such as the Third Generation Partnership Project (3GGP) Releasc 8 specifications.

Mobile terminals operating in a CELL_FACH mode may use a contention based E-DCH channel for UL transmission rather than a traditional random access channel (RACU). The contention-based E-DCH channel allows for mobile terminals to transfer signalling and data at significantly higher data rates and for longer durations, which reduces transfer and state transition delays.

In order to limit errors due to fading and interference on the uplink from a mobile terminal (also known as user equipment) to the network, data may be divided into blocks with the bits within a block being encoded and interleaved. The size of a block is related to a transmission time interval (TTI) as each block must be transmitted within the TTI. Upon receipt of a block, a network entity may dc-interleave and decode the bits and may then estimate the bit error rate as a result of the transmission of the block within the TTI. The TTI is therefore the shortest period over which the network entity can estimate the bit error rate. In networks that utilise link adaptation techniques based on the estimated bit error rate, the shortest interval between reports of the estimated performance, that is, between reports of the bit error rate, is a single TTI.

Thus, the length of the TTI generally limits a network's responsiveness in adapting to changed conditions on the uplink. In order to adapt more quickly to the changing conditions on an uplink, shorter Ills may be desired. However, the desire for short S TTIs may be offset by the increased efficiencies in error correction and compression teclmiques and the increased benefits from interleaving that are provided by longer TT Is.

Various TTIs have been defined including a lOms III and a 2ms ITT. For example, support for concurrent deployment of TTI settings (e.g. 2 ms and 10 ms) will be allowed for the common E-DCH in the CELL_EACH state. In this regard, 3GGP Release 11 (Rd-I I) supports concurrent deployment of 2 ms and 10 ms TTI seftings in a cell. A single TTI setting, which may be determined and broadcast by a communications network, may be used by mobile terminals accessing the E-DCH in the CELL_FACFI state within a particular cell.

The 2ms TTI allows for a quicker adaptation to uplink conditions, thereby allowing the transmission of data blocks to be quickly scheduled while the uplink is temporarily enjoying improved conditions. As a result, a 2ms Ill may allow data to be transmitted over an uplink having better than average conditions such that the bit rate transmitted via the uplink may be higher than that allowed by avcragc conditions, thereby correspondingly increasing the network capacity. However, a smaller TTI, such as a 2ms TTI, may only be workable in an instance in which the mobile terminal or other user equipment is located within a central portion of a coverage area since a mobile terminal or other user equipment near the edge of the coverage area may be unable to successfully transmit data in accordance with the smaller TTI.

Thus, in an instance in which a smaller TTI was initially selected, such as in an instance in which the mobile terminal was within a central region of the coverage area at the time that the smaller TTI was selected, the mobile terminal may need to switch to a longer TTl in an instance in which the mobile terminal moves so as to be closer to the edge of the coverage area. Additionally, the initial selection of the TTI may, in some instances, be based upon an inaccurate measurement such that the initial selection of a smaller TTI may be incorrect, thereby creating an immediate desire to switch to a longer TTI.

S

Summary

According to a first aspect of the present invention, there is provided a method comprising: selecting a first transmission time interval (TTI) resourco in conjunction with an uplink; dctccting a failure condition associated with the uplink; and selccting a second TTI resource, different from the first TTI resource, in response to detection of the failure condition.

According to a sccond aspect of thc prcsent invention, therc is providcd apparaths comprising: a processing system constructed and arranged to cause the apparatus to at least: select a first transmission timc interval (TTI) resourcc in conjunction with an uplink; detect a failure condition associated with the uplink; and select a second TTI resource, different from the first TTI resource, in response to detection of the failure condition.

According to a third aspect of the present invention, there is provided computer program comprising program instructions configured to: sciect a first transmission time interval (TTI) resource in conjunction with an uplink; detect a failure condition associated with the uplinlc and select a second TTI resource, different from the first TTI resource, in response to detection of the failure condition.

In yet another embodiment, an apparatus is provided that includes means for sclccting a first TTT resource in conjunction with an uplink. The apparatus of this embodiment also includes means for detecting a failure condition associated with the uplink and means for selecting a second TTI resource, different from the first TTI resource, in response to detection of the failure condition.

A method, apparatus and computer program arc provided in accordance with an example embodiment of the present invention in order to allow for reselection of a TTI resource. As such, the method, apparatus and computer program of one embodiment may provide for the reselection of a TTI resource in an instance in which a mobile S terminal has moved to a different portion of the coverage area and/or in an instance in which the TTI resource was initially incorrectly selected, such as based upon an inaccurate measurement. As such, the method, apparatus and computer program of an example embodiment of the present invention provide for adaptation of the TTI resource so as to provide for improved cfficicncy in regards to the transmission of data via an uplink.

The processing system may comprise at least one processor and at least one memory including computer program code, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the I 5 apparatus to at least operate as described above.

The computer program may be provided in the form of a computer program product comprising at least one non-transitory computer-readable storage medium having computer-readable program instructions stored therein.

Further features and advantages of the invention will bccomc apparent from thc following description of preferred embodiments of the invention, given by way of example only, which is made with reference to the accompanying drawings.

Brief DcscriDtion of the Drawings Figure 1 shows a schematic representation of a system which may support rcs&cction of a TTT resource in conjunction with the transmission of data via an uplink in accordance with an example embodiment of the present invention; Figure 2 shows a block diagram of an apparatus that they may be embodied by a mobile terminal in accordance with an example embodiment of the present invention; Figure 3 shows a flowchart illustrating operations performed in accordance with an example embodiment of the present invention; S Figure 4 shows a graphical representation of an increase in preamble power to a power level that no longer satisfies the predefined threshold and that serves as a failure condition for triggcring reselection of a TTI rcsourcc in accordancc with an example embodiment of thc prcscnt invention; Figure 5 shows a graphical representation of the retransmission of the preamble a predefined number of times which represents a failure condition so as to trigger reselection of a TTI resource in accordance with an example embodiment ofthe present invention; Figure 6 shows a signal flow diagram in which an unrecoverable crror in the uplink serves as a failure condition so as to trigger selection of a different TTI resource in accordance with an example embodiment of the present invention; and Figure 7 shows a signal flow diagram in which the failure to receive a response from the network relating to a transition from one TTI resource to another TTI resource serves as the failure condition so as to trigger the selection of a different TTI resource in accordance with an example embodiment of the present invention.

Detailed Description

The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all embodiments, of the inventions are shown. Indeed, the invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Like numbers refer to like elements throughout.

As used in this application, the term "circuitry" refers to all of the following: (a) hardware-only circuit implementations (such as implementations in only analog and/or digital circuitry) and (b) to combinations of circuits and software (and/or firmware), such as (as applicable): (i) to a combination of processor(s) or (ii) to portions of S processor(s)/software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions) and (c) to circuits, such as a microprocessor(s) or a portion of a microprocessor(s), that require software or firmware for operation, even if the softwarc or firmware is not physically prcscnt.

This definition of "circuitry" applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term "circuitry" would also cover an implementation of merely a processor (or multiple processors) or portion of a processor and its (or their) accompanying software and/or firmware. The term "circuitry" would also cover, for example and if applicable to the particular claim clement, a bascband integrated circuit or application specific integrated circuit for a mobile phone or a similar integrated circuit in server, a cellular network device, or other network device.

A method, apparatus and computer program arc provided in accordance with an cxamplc cmbodimcnt of the prcscnt invcntion in order to allow for thc rcsclcction of a TTI resource, such as in an instance in which a mobile terminal has moved to a different portion of the coverage area and/or in an instance in which the TTI resource was initially incorrectly selected, such as based upon an inaccurate measurement. As such, the method, apparatus and computer program of an cxamplc embodiment of the present invention provides for adaptation of the TTI resource so as to provide for improved efficiency in regards to the transmission of data via an uplink.

Although the method, apparatus and computer program may be implemented in a variety of different systems, one example of such a system is shown schematically in Figure 1, which includes a first communication device (e.g. mobile terminal 10) that is capable of communication via a network entity 14, such as an access point, e.g. a base station, a Node B, an evolved Node B (eNB), serving cell or other access point, with a network 12 (e.g. a core network). While the network may be configured in accordance with Long Term Evolution (LIE) or LIE-Advanced (LTE-A), other networks may S support the method, apparatus and computer program of embodiments of the present invention, including those configured in accordance with wideband code division multiple access (W-CDMA), CDMA2000, global system for mobile communications (GSM), general packet radio service (GPRS) and/or the like.

The network 12 may include a collection of various different nodes, devices or functions that may be in communication with each other via corresponding wired and/or wireless interfaces. For example, the network may include one or more cells, supported by respective access points, each of which may serve a respective coverage area. The cells could be, for example, part of one or more cellular or mobile networks or public land mobile networks (PLMN5). In turn, other devices such as processing devices (e.g. personal computers, server computers or the like) may be coupled to the mobile terminal 10 and/or other communication devices via the network.

A communication device, such as the mobile terminal 10 (also known as user equipment (liE)), may be in communication with other communication devices or other devices via the network entity 14, e.g. an access point, and, in turn, the network 12. In some cases, the communication device may include an antenna for transmitting signals to and for receiving signals from a serving cell.

In some example embodiments, the mobile terminal 10 may be a mobile communication device such as, for example, a mobile telephone, portable digital assistant (PDA), pager, laptop computer, or any of numerous other hand held or portable communication devices, computation devices, content generation devices, content consumption devices, or combinations thereof. As such, the mobile terminal 10 may include one or more processors that may define processing circuitry either alone or in combination with one or more memories. The processing circuitry may utilise instructions stored in the memory to cause the mobile terminal 10 to operate in a particular way or execute specific functionality when the instructions are executed by the one or more processors. The mobile terminal 10 may also include communication circuitry and corresponding hardware/software to enable communication with other S devices andlor the network 12.

In one embodiment, for example, the mobile terminal 10 maybe embodied as or otherwise include an apparatus 20 as generically represented by the block diagram of Figure 2. While the apparatus 20 may be employed, for example, by a mobile terminal 10, it should be noted that the components, devices or elements described below may not be mandatory and thus some may be omitted in certain embodiments.

Additionally, some embodiments may include further or different components, devices or elements beyond those shown and described herein.

As shown in Figure 2, the apparatus 20 may include or otherwise be in communication with processing circuitry 22 that is configurable to perform actions in accordance with example embodiments described herein. The processing circuitry may be configured to perform data processing, application execution and/or other processing and management services according to an example embodiment of the present invention. In some embodiments, the apparatus or the processing circuitry may be embodied as a chip or chipset. In other words, the apparatus or the processing circuitry may comprise one or more physical packages (e.g. chips) including materials, components and/or wires on a structural assembly (e.g. a baseboard). The structural assembly may provide physical strength, conservation of size, and/or limitation of electrical interaction for component circuitry included thereon. The apparatus or the processing circuitry may therefore, in some cases, be configured to implement an embodiment of the present invention on a single chip or as a sing'e "system-on-a-chip".

As such, in some cases, a chip or chipset may constitute means for performing one or more operations for providing the frmnctionalities described herein.

In an example embodiment, the processing circuitry 22 may include a processor 24 and memory 26 that may be in communication with or otherwise control a communication interface 28 and, in some cases, a user interface 30. As such, the processing circuitry may be embodied as a circuit chip (e.g. an integrated circuit chip) S configured (e.g. with hardware, software or a combination of hardware and software) to perform operations described herein. However, in some embodiments taken in the context of the mobile terminal 10, the processing circuitry may be embodied as a portion of a mobile computing dcvicc or other mobile terminal.

The user interface 30 (if implemented) may be in communication with the processing circuitry 22 to receive an indication of a user input at the user interface and/or to provide an audible, visual, mechanical or other output to the user. As such, the user interface may include, for example, a keyboard, a mouse, a joystick, a display, a touch screen, a microphone, a speaker, and/or other input/output mechanisms.

The communication interface 28 may include one or more interface mechanisms for enabling communication with other devices and/or networks. In some cases, the communication interface may be any means such as a device or circuitry embodied in either hardware, or a combination of hardwarc and software that is configured to receive and/or transmit data from/to a network 12 and/or any other deviec or module in communication with the processing circuitry 22, such as between the mobile terminal and the network entity 14. In this regard, the communication interface may include, for example, an antenna (or multiple antennas) and supporting hardware and/or software for enabling communications with a wireless communication network and/or a communication modem or other hardware/software for supporting communication via cable, digital subscriber line (DSL), universal serial bus (IJSB), Ethernet or other methods.

In an example embodiment, the memory 26 may include one or more non-transitory memory devices such as, for example, volatile and/or non-volatile memory that may be either fixed or removable. The memory may be configured to store information, data, applications, instructions or thc like for enabling thc apparatus 20 to carry out various functions in accordance with example embodiments of the present invention. For example, the memory could be configured to buffer input data for processing by the processor 24. Additionally or alternatively, the memory could be S configured to store instructions for execution by the processor. As yet another alternative, the memory may include one of a plurality of databases that may store a varicty of files, contents or data scts. Among thc contents of the memory, applications may be stored for execution by the processor in order to carry out the functionality associated with each respective application. In some cases, the memory may be in communication with the processor via a bus for passing information among components of the apparatus.

The processor 24 may be embodied in a number of different ways. For example, the processor may be embodied as various processing means such as one or more of a microprocessor or other processing element, a coprocessor, a controller or various other computing or processing devices including integrated circuits such as, for example, an ASIC (application specific integrated circuit), an FPGA (field programmable gate array), or the like. In an example embodiment, the processor may be configured to execute instructions stored in the memory 26 or otherwise accessible to the processor.

As such, whether configured by hardware or by a combination of hardware and software, the processor may represent an entity (e.g. physically embodied in circuitry, in the form of processing circuitry 22) capable of performing operations according to embodiments of the present invention while configured accordingly. Thus, for example, when the processor is embodied as an ASIC, FPGA or the like, the processor may be specifically configured hardware for conducting the operations described herein. Alternatively, as another example, when the processor is embodied as an executor of software instructions, the instructions may specifically configure the processor to perform the operations described herein.

Figure 3 is a flowchart illustrating schematically the operations performed by an example of a method, apparatus and computer program, such as apparatus 20 of Figure 2, from the perspective of a mobile terminal 10 in accordance with one embodiment of the present invention. It will be understood that each block of the flowchart, and combinations of blocks in the flowchart, maybe implemented by various means, such as hardware, firmware, processor, circuitry and/or other device associated S with execution of software including one or more computer program instructions. For example, one or more of the procedures described above may be embodied by computer program instructions. In this regard, the computer program instructions which embody the procedures described above may be stored by a memory device 26 of an apparatus cmploying an cmbodimcnt of the prcscnt invcntion and cxccutcd by a proccssor 24 in the apparatus. As will be appreciated, any such computer program instructions may be loaded onto a computer or other programmable apparatus (e.g. hardware) to produce a machine, such that the resulting computer or other programmable apparatus provides for implementation of the functions specified in the flowchart block(s). These computer program instructions may also be stored in a non-transitory computer-readable storage memory that may direct a computer or other programmable apparatus to function in a particular manner, such that the instructions stored in the computer-readable storage memory produce an article of manufacture, the execution of which implements the function specified in the flowchart block(s). The computer program instructions may also be loaded onto a computer or other programmable apparatus to cause a series of operations to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide operations for implementing the functions specified in the flowchart block(s). As such, the operations of Figure 3, when executed, convert a computer or processing circuitry into a particular machine configured to perform an example embodiment of the present invention. Accordingly, the operations of Figure 3 define an algorithm for configuring a computer or processing circuitry 22, e.g. processor, to perform an example embodiment. In some cases, a general purpose computer may be provided with an instance of the processor which performs the algorithm of Figure 3 to transform the general purpose computer into a particular machine configured to perform an example embodiment.

Accordingly, blocks of the flowcharts support combinations of means for performing the specified functions and combinations of operations for performing the specified functions. It will also be understood that one or more blocks of the flowchart, and combinations of blocks in the flowchart, can be implemented by special purpose S hardware-based computer systems which perform the specified functions, or combinations of special purpose hardware and computer instructions.

In some embodiments, certain ones of the operations above maybe modified or further amplified as described below. Morcovcr, in somc embodiments additional optional operations may also be included. It should be appreciated that each of the modifications, optional additions or amplifications below may be included with the operations above either alone or in combination with any others among the features described herein.

Referring now to Figure 3, the operations performed by a method, apparatus and computer program of an example embodiment are illustrated. As shown by block 40, an apparatus 20 embodied by the mobile terminal 10 may include means, such as the processing circuitry 22, the processor 24 or the like, for selecting a first transmission time interval (TTI) resource in conjunction with an uplink. The first TTI resource defines a respective time period and, in one example embodiment, is a 2ms TTI resource that defines a time period of 2ms in which to transmit a block of data via the uplink to a network entity 14, such as an access point or the like. The first TTI resource may be configured for either normal operation or for bundling operation. In regards to normal operation, a data packet is transmitted a single time via the uplink to a network entity within the first TTI. Following transmission of the block of data within the first TTI, the mobile terminal may await an acknowledgement from the network entity indicative of the successful receipt of the block of data. Tn accordance with a bundling operation, however, the same block of data may be transmitted via the upl ink a predefined number of times with each transmission of the block of data being performed within a time period defined by the first TTI. A bundling operation therefore transmits the same block of data multiple times without waiting for an acknowledgment from the network entity until the block of data has been transmitted the predefined number of times. Thus, a bundling operation increases the likelihood that the block of data is successthlly received by the network entity, albeit at the expense of the transmission rate.

S The first TTI resource may be selected in various manners. In one embodiment, the selection of the first TTI resource is based upon the power with which the preamble is transmitted by the mobile terminal 10 to the network entity 14, such as via a random access channel (RACEI), a physical random access channel (PRACH) or the like, in order to establish a dedicated channel, such as an E-DCH, to support communications therewith. The power with which the preamble is transmitted via the uplink may, in turn, be based upon an estimation of the interference or path loss along the uplink. As such, the selection of the first TTI resource may additionally or alternatively be based upon the interference and/or the path loss along the uplink from the mobile terminal to the network entity.

The power with which the preamble is transmitted via the uplink generally varies based upon the estimated interference and!or path loss along the uplink, with the preamble being transmitted with greater power in an instance in which the estimated interference and/orpath loss is greater, such as in instances in which the mobile terminal 10 is near an edge of a coverage area, e.g. a cell. Conversely, the preamble is generally transmitted with lower power in an instance in which the estimation of the interference and/or path loss is less, such as in an instance in which the mobile terminal is within a central portion of the coverage area.

In instances in which the first TTI resource is the smaller or shorter TTI resource, such as a 2ms TTI resource, relative to the second TTI resource that will be discussed below, the apparatus 20, such as the processing circuitry 22, the processor 24 or the like, may be configured to select the smaller TTI resource in an instance in which the power with which the preamble is transmitted via the uplink is less than a predefined threshold, thereby indicating that the mobile terminal 10 may be within a central portion of the coverage area so as to permit data to be transmitted to the network entity within a smaller TTI.

With reference to block 42 of Figure 3, the apparatus 20 embodied by the mobile S terminal 10 may also include means, such as the processing circuitry 22, the processor 24 or the like, for detecting a failure condition associated with the uplink. The apparatus may also include means, such as the processing circuitry, the processor or the like, for selecting a second TTI resource, different from the first TTI resource, in response to the detection of the failure condition. Sec block 44.

Various failure conditions associated with the uplink may be defined in accordance with embodiments of the present invention. As illustrated in Figure 4, for example, one failure condition may be the change in the power level of the preamble prior to the receipt of a successful acknowledgement (ACK) from the network entity 14 such that the power level of the preamble no longer satisfies the predefined threshold that was required for the initial selection of the first TTI resource. In this regard, the initial power P0 with which the preamble is transmitted is shown by the leftmost bar in Figure 4. As described above, this initial power P0 with which the preamble is transmitted may be based upon the estimated interference and/or path loss along the uplink. Following transmission of the preamble having the initial power level P0, the mobile tcrminal 10, such as the communications interface 28, thc processing circuitry 22, the processor 24 or the like, may then await the receipt of a successful acknowledgement from the network entity, such as may be provided via an indicator channel, e.g. an enhanced acquisition indicator channel (E-AICFI), prior to establishing a dedicated channel between the mobile terminal and the network entity to support the transmission of blocks of data.

In an instance in which the mobile terminal 10, such as the communication interface 28, the processing circuitry 22, the processor 24 or the like, fails to receive an acknowledgement, the apparatus 20 embodied by the mobile terminal, such as the communications interface, the processing circuitry, the processor or the like, may increase the power with which the preamble is transmitted by a predefined increment APO. The apparatus embodied by the mobile terminal may then retransmit the preamble having an increased power level, such as a power defined as P0 + APO, as shown in Figure 4. The apparatus embodied by the mobile terminal then again waits for the S receipt of an acknowledgement from the network entity 42 of the successful receipt of the preamble having the increased power level. In an instance in which the apparatus embodied by the mobile terminal fails to receive such a successful acknowledgement from the network entity, the power with which the preamble is transmitted may be repeatedly increased, such as in steps of APO, and the preamble may be retransmitted, albeit with an increasingly higher power level.

In accordance with an example embodiment, the apparatus 20 embodied by the mobile terminal 10, such as the processing circuitry 22, the processor 24 or the like, may determine an instance in which the power with which the preamble is retransmitted no longer satisfies the threshold that was required for the initial selection of the first TTI resource. As shown in the embodiment of Figure 4, for example, the power level with which the preamble is retransmitted may be increased so as to exceed the predefined threshold that was required for the initial selection of the first TTI resource.

In this embodiment, the change, such as the increase, in the power level with which the preamble is retransmitted prior to the receipt of a successful acknowledgement from the network entity 42 such that the power level of the preamble no longer satisfies the predefined threshold may be defined to be the failure condition that will, in turn, trigger selection of a different TTI resource.

Additionally or alternatively, a maximum number of retransmissions may be predefined. In this embodiment, such as shown in Figure 5, the preamble may be repeatedly transmitted via the uplink with increasingly greater power level in instances in which the apparatus 20 embodied by the mobile terminal 10 fails to receive a successful acknowledgment from network entity 42. In this embodiment, the power level with which the preamble is transmitted may continue to satisfy the predefined threshold, such as by being less than the prcdefined threshold as shown in the embodiment of Figure 5. However, the retransmission of the preamble with an increasingly greater power level for the predefined maximum number of times, e.g. 4 times in the embodiment of Figure 5, without receipt of a successftil acknowledgment from the network entity may be defined as the failure condition associated with the uplink that will, in turn, trigger selection of a different TTI resource.

In another embodiment, the transmission of the preamble from the mobile terminal 10 to the network entity 14 may be successfully acknowledged such that a channel, such as an E-DCH, is established between the mobile terminal and network entity with blocks of data being transmitted in accordance with the first TTI resource such as within 2ms. As shown in Figure 6, the failure condition of this embodiment may be an unrecoverable error in the uplink. As such, the apparatus 20 embodied by the mobile terminal, such as the processing circuitry 22, the processor 24, the communication interface 2 or the like, may be configured to detect an unrecoverable error in the uplink, such as a radio link control (RLC) unrecoverable error, a maximum number of hybrid automatic repeat request (EIARQ) retransmissions or other unrecoverable error. Once the unrecoverable error in the uplink has been detected, the apparatus embodied by the mobile terminal, such as the processing circuitry, the processor or the like, may select a different TTI resource.

In yet another embodiment, the failure to receive a response from the network entity 14 in regard to an indication relating to the transition from the first TTI resource to a second TTI resource may serve as the failure condition. In this regard, the initial transmission of the preamble from the mobile terminal 10 to the network entity may be successfully acknowledged such that a channel, such as an E-DCH, is established between the mobile terminal and the network entity. While the channel remains established, the apparatus 20 embodied by the mobile terminal, such as the processing circuitry 22, the processor 24 or the like, may determine that the predefined criteria that has been established for the selection of a different TTI resource may be met, as shown in Figure 7. A variety of predefined criteria may be established to trigger the selection of a different TTI resource but, in one embodiment, the predefined criteria may be based on buffer occupancy, based on radio conditions, e.g. pathioss, interference, ccli coverage, received signal code power, or based on the relationship of the channel quality index (CQI) to a predefined threshold.

S In response to the determination that at least one of the predefined criteria for the selection of a different TTI resource has been met, the apparatus 20 embodied by the mobile terminal 10 of this embodiment, such as the processing circuitry 22, the processor 24, the communication interface 28 or the like, may cause an indication to be transmitted to the network entity 14 indicating that a transition is to be made from thc first TTI resource to a second, different TTI resource, as shown in Figure 7. Although various types of indications may be provided, the mobile terminal, such as the processing circuitry, the processor, the communication interface or the like, may provide a layer I (LI) CQI or layer 2 (L2) system information (SI) indication in one embodiment. In response to the indication regarding the impending transition from the first TTI resource to the second TTI resource, the apparatus embodied by the mobile terminal, such as the processing circuitry, the processor, the communication interface or the like, may await an acknowledgement from the network entity, such as a high speed-shared control channel (HS-SCCH) order from the network entity to switch to the second TTI resource. In this embodiment, the apparatus embodied by the mobile terminal, such as the processing circuitry, the processor, the communication interface or the like, may await the acknowledgement or other response from the network entity for a predefined period of time. In an instance as shown in Figure 7 in which the acknowledgement or other response from the network entity is not received by the mobile terminal within the predefined period of time, the failure to have received the acknowlcdgmcnt or other response from the network entity may be the failure condition associated with the uplink, thereby triggering the selection of the second TTI resource unilaterally by the mobile terminal even though the network entity did not acknowledge or otherwise respond to the prior indication relating to the transition from the first TTI resource to the second TTI resource.

Regardless of the manner in which the failure condition associated with the uplink is detected, the detection of the failure condition causes the apparatus 20 embodied by the mobile terminal 10, such as the processing circuitry 22, the processor 24 or the like, to select a second TTI resource, different from the first ITI resource. In S one embodiment, the second TTI resource defines a greater time period than the first TTI resource. For example, the first TTI resource may define a time period of 2 ms, while the second TTI resource may define a time period of 10 ms. By reselecting a second TTI resource that defines a greater time period than the first TTI resource, the method, apparatus and computcr program of an example embodiment of the present invention provides a greater time period for transmitting a block of data via the uplink, thereby increasing the likelihood that the mobile terminal may successfully communicate with the network entity 14 even in an instance in which the mobile terminal is near an edge of the coverage area.

In addition to or instead of selecting a TTI resource that defines a longer period of time in response to the detection of the failure condition, the apparatus 20 embodied by the mobile terminal 10, such as the processing circuitry 22, the processor 24 or the like, may select a different type of TTI resource. For example, the first TTI resource that is selected in accordance with one embodiment may provide for normal operation in which a single block of data is transmitted via the uplink with the mobile terminal then awaiting acknowledgement by the network entity 14. In this cmbodiment, the apparatus embodied by the mobile terminal, such as the processing circuitry, the processor or the like, may select a second TTI resource in response to the detection of the failure condition in which the second TTI resource defines either the same or a different time period than the first TTI resource, but in which the second TTI resource implements a bundling operation in which the same block of data is transmitted a plurality of times, such as five or more times for example, via the uplink prior to awaiting receipt of an acknowledgement from the network entity, thereby increasing the likelihood that the network entity will successfully receive the data packet even in instances in which the mobile terminal is near an edge of the coverage area.

By reselecting the TTI resource in response to the detection of a failure condition while utilising the first TTI resource, the reliability with which a mobile terminal 10 may transmit blocks of data to a network entity 14 via the uplink may be improved. However, the method, apparatus and computer program of an example S embodiment do endeavour to take advantage of a shorter TTI resource when network conditions permit so as to increase the rate at which data is transmitted from the mobile terminal to the network entity and to correspondingly increase network utilisation, while still being able to automatically adapt to changing conditions, such as movement of thc mobile terminal from a central portion of the coverage area to an edge of the coverage area, or to correct for errors associated with the initial selection of the first TTI resource by automatically reselecting a different TTI resource in response to the detection of a failure condition.

Many modifications and other embodiments of the inventions set forth herein will come to mind to one skilled in the art to which this invention pertains having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the invention is not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Moreover, although the foregoing descriptions and the associated drawings describe example embodiments in the context of certain example combinations of elements and/or frmnctions, it should be appreciated that different combinations of elements and!or functions may be providedby alternative embodiments without departing from the scope of the appended claims. In this regard, for example, different combinations of elements and/or functions than those explicitly described above are also contemplated as may be set forth in some of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

The above embodiments are to be understood as illustrative examples of the invention. Further embodiments of the invention are envisaged. It is to be understood that any feature described in relation to any one embodiment may be used alone, or in combination with other features described, and may also be used in combination with one or more features of any other of the embodiments, or any combination of any other of the embodiments. Furthermore, equivalents and modifications not described above may also be employed without departing flx,m the scope of the invention, which is defined in the accompanying claims.

Claims

CLAIMS1. A method comprising: selecting a first transmission lime interval (TTI) resource in conjunction with S an uplink; detecting a failure condition associated with the uplink; and selecting a second TTI resource, different from the first TTI resource, in response to detection of the failure condition.
2. A method according to claim 1, wherein the second TTI resource defines a greater time period than the first TTI resource.
3. A method according to claim 2, wherein the first and second TTI resources define time periods of 2 ms and 10 ms respectively.
4. A method according to any of claims I to 3, wherein the second TTI resource relies upon bundling of data packets on the uplink.
5. A method according to any of claims I to 4, wherein selecting the first TTI resource comprises determining that a power level of a preamble of data packets transmitted via the uplink satisfies a prcdcfincd threshold, and wherein detecting the failure condition comprises detecting a change in the power level of a retransmission of the preamble prior to receipt of a successful acknowledgement from a network entity such that the power level of the retransmission of the preamble no longer satisfies the predefined threshold.
6. A method according to any of claims I to 5, wherein detecting the failure condition comprises detecting that the preamble has been retransmitted at least a predefined number of times prior to receipt of a successful acknowledgement from a network entity.
7. A method according to any of claims 1 to 6, whercin detccting thc failure condition comprises detecting an unrecoverable error in the uplink.
8. A method according to any of claims Ito 7, comprising causing an indication S to be transmitted to a network entity indicating a transition from the first TTI resource to the second TTI resource, wherein detecting the failure condition comprises failing to receivc a response from the network entity in regard to the indication regarding the transition from the first TTI resource to the second TTI resource.
9. Apparatus comprising: a processing system constructed and arranged to cause the apparatus to at least: select a first transmission time interval (TTI) resource in conjunction with an uplink; detect a failure condition associated with the uplink; and select a second TTI resource, different from the first TTI resource, in response to detection of the failure condition.
10. Apparatus according to claim 9, wherein the second TTI resource defines a greater time period than the first TTI resource.
11. Apparatus according to claim 10 wherein the first and second TTI resources define time periods of 2 ms and 10 ms respectively.
12. Apparatus according to any of claims 9 to 11, wherein the second TTI resource relics upon bundling of data packets on the uplink.
13. Apparatus according to any of claims 9 to 12, wherein the processing system is arranged to cause the apparatus to select the first TTI resource by determining that a power level of a preamble of data packets transmitted via the uplink satisfies a predefined threshold, and to cause the apparatus to detect the failure condition by detecting a change in the power level of a retransmission of the preamble prior to receipt of a successful acknowledgement from a network entity such that thc power level of the retransmission of the preamble no longer satisfies the predefined threshold.
14. Apparatus according to any of claims 9 to 13, wherein the processing system is arranged to cause the apparatus to detect the failure condition by detecting that the preamble has been retransmitted at least a predefined number of times prior to receipt of a successful acknowledgement from a network entity.
15. Apparatus according to any of claims 9 to 14, whcrcin thc proccssing system is arranged to cause the apparatus to detect the failure condition by detecting an unrecoverable error in the uplink.
16. Apparatus according to any of claims 9 to 15, wherein the processing system is arranged to cause the apparatus to cause an indication to be transmitted to a network entity indicating a transition from the first TTI resource to the second TTI resource, and to cause the apparatus to detect the failure condition by failing to receive a response from the network entity in regards to the indication regarding the transition from the first TTI resource to the second TTI resource.
17. A computer program comprising program instructions configured to: select a first transmission time intewal (TTI) resource in conjunction with an uplink; detect a failure condition associated with the uplink; and select a second TTI resource, different from the first TTI resource, in response to detection of the failure condition.
18. A computer program according to claim 17, wherein the second TTT resource defines a greater time period than the first TTI resource.
19. A computer program according to claim 18, wherein the first and second TTI resources define respective time periods of 2 ms and 10 ms.
20. A computer program according to any of claims 17 to 19, wherein the second TTI resource relies upon bundling of data packets on the uplink.
21. A computer program according to any of claims 17 to 20, wherein the program instructions configured to select the first TTI resource comprise program instructions configured to determine that a power level of a preamble of data packets transmitted via the uplink satisfies a predefined threshold, and wherein the program instructions configurcd to dctcct the failure condition comprise program instructions configured to detect a change in the power level of a retransmission of the preamble prior to receipt of a successful acknowledgement from a network entity such that the power level of the retransmission of the preamble no longer satisfies the predefined threshold.
22. A computer program according to any of claims 17 to 21, wherein the program instructions configured to detect the failure condition comprise program instructions configured to detect that the preamble has been retransmitted at least a prcdcfincd number of times prior to receipt of a successful acknowledgement from a network entity.
23. A computer program according to any of claims 17 to 22, wherein the program instructions configured to detect the failure condition comprise program instructions configured to detect an unrecoverable error in the uplink.
24. A computer program according to any of claims 17 to 23, comprising program instructions configured to cause an indication to be transmitted to a network entity indicating a transition from the first TTI resource to the second TTI resource, wherein the program instructions configured to detect the failure condition comprise program instructions configured to recognise a failure to receive a response from the network entity in regards to the indication regarding the transition from the first TTI resource to the second TTI resource.
25. A method for reselecting a different transmission time interval resource, substantially in accordance with any of the examples as described herein with reference to the accompanying drawings.
26. A processing system for a wireless device for reselecting a different iransmission time interval resource, substantially in accordance with any of the examples as described herein with reference to the accompanying drawings.
27. A wirclcss dcvicc for reselecting a different transmission timc interval resource, substantially in accordance with any of the examples as described herein with reference to the accompanying drawings.