Patent Application
20120327867
The invention relates to wireless communications, and, particularly, to subframe scheduling.
In a radio system, a base station assigns radio resources to a terminal and signals this information to the terminal using a control channel. In 3GPP Long Term Evolution (LTE), transmissions are performed in one millisecond time periods called subframes. A downlink (DL) assignment or an uplink (UL) grant is transmitted when resources in a subframe are assigned for the terminal. Semi-persistent scheduling enables radio resources to be semi-statically configured and allocated to a terminal for a longer time period, avoiding the need for specific downlink assignment or uplink grant to be sent in every subframe.
According to an aspect of the present invention, there is provided an apparatus comprising: at least one processor; and at least one memory including computer program code; the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus to perform at least the following: obtain a reverse scheduling received by a terminal from a base station, the reverse scheduling comprising information indicating that at least a part of subframes is not utilized for a radio data transmission between the terminal and the base station; and cause a radio transceiver of the terminal to operate according to the reverse scheduling in the radio data transmission between the terminal and the base station.
According to another aspect of the present invention, there is provided another apparatus comprising: at least one processor; and at least one memory including computer program code; the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus to perform at least the following: create a reverse scheduling for a terminal, the reverse scheduling comprising information indicating that at least a part of subframes is not utilized for a radio data transmission between the terminal and a base station; cause a transmission of the reverse scheduling from the base station to the terminal; and cause a radio transceiver of the base station to operate according to the reverse scheduling in the radio data transmission between the terminal and the base station.
Example embodiments of the present invention are described below, by way of example only, with reference to the accompanying drawings, in which
The following embodiments are only examples. Although the specification may refer to “an”, “one”, or “some” embodiment(s) in several locations, this does not necessarily mean that each such reference is to the same embodiment(s), or that the feature only applies to a single embodiment. Single features of different embodiments may also be combined to provide other embodiments. Furthermore, words “comprising” and “including” should be understood as not limiting the described embodiments to consist of only those features that have been mentioned and such embodiments may contain also features/structures that have not been specifically mentioned.
As shown in
In another embodiment, shown in
Additionally, the at least one memory 104 and the computer program code 106 are configured to, with the at least one processor 102, cause the first apparatus 100 to perform also the following: obtain 108 a reverse scheduling received by the terminal from the base station.
Furthermore, the at least one memory 104 and the computer program code 106 are configured to, with the at least one processor 102, cause the first apparatus 100 to perform also the following: cause 116 changes to the semi-persistent scheduling on the basis of the reverse scheduling, thereby arriving at a reversed semi-persistent scheduling.
Finally, the at least one memory 104 and the computer program code 106 are configured to, with the at least one processor 102, cause the first apparatus 100 to perform also the following: cause 110 a radio transceiver of the terminal to operate according to the reversed semi-persistent scheduling in the radio data transmission between the terminal and the base station.
The first apparatus 100 may be a terminal, e.g. user equipment (UE), a radio terminal, a subscriber terminal, smartphone, mobile station, mobile phone, portable computer, pad computer or some other type of wireless mobile communication device operating with or without a subscriber identification module (SIM). The terminal may be a piece of equipment or a device that is configured to associate the terminal and its user with a subscription and allows a user to interact with the radio system, e.g. the terminal is capable of requesting service from the radio system. The terminal presents information to the user and allows the user to input information. In other words, the terminal may be any terminal capable of wirelessly receiving information from and/or wirelessly transmitting information to the radio system. Besides communication capabilities, the terminal may include computer functionalities or functionalities of other data processing devices.
However, the first apparatus 100 may also be interpreted as a circuitry implementing the required functionality within the terminal. As was explained, the first apparatus 100 obtains 108 the reverse scheduling, and causes 110 the data transmission according to the reverse scheduling.
If the first apparatus 100 is the terminal, then it will also comprise the equipment needed for the communication, such equipment including at least one radio transceiver with all the required hardware and software. On the other hand, if the first apparatus 100 is the circuitry, then it will not necessarily comprise the radio transceiver(s) etc. but only interfaces enabling communication with such equipment implementing the communication with the base station, for example. The first apparatus 100 may be a wireless modem designed to be used in a terminal, or in any other product, such as cars, sensor networks, multimedia, or another product requiring wireless communication capabilities. The wireless modem may be designed for a terminal, or it may be a separate product, such as a USB (Universal Serial Bus) stick capable of being plugged into a product, such as a portable computer, or any other product requiring wireless communication capabilities.
As shown in
In another embodiment, shown in
Additionally, the at least one memory 134 and the computer program code 136 are configured to, with the at least one processor 132, cause the second apparatus 130 to perform also the following: cause 146 a transmission of the semi-persistent scheduling from the base station to the terminal.
The at least one memory 134 and the computer program code 136 may be configured to, with the at least one processor 132, cause the second apparatus 130 to perform the following: cause 148 a radio transceiver of the base station to operate according to the semi-persistent scheduling in the radio data transmission between the terminal and the base station.
Additionally, the at least one memory 134 and the computer program code 136 are configured to, with the at least one processor 132, cause the second apparatus 130 to perform also the following: create 138 a reverse scheduling for the terminal, and cause 140 a transmission of the reverse scheduling from the base station to the terminal.
Additionally, the at least one memory 134 and the computer program code 136 are configured to, with the at least one processor 132, cause the second apparatus 130 to perform also the following: cause 150 changes to the semi-persistent scheduling on the basis of the reverse scheduling, thereby arriving at a reversed semi-persistent scheduling, and cause 142 a radio transceiver of the base station to operate according to the reversed semi-persistent scheduling in the radio data transmission between the terminal and the base station.
The second apparatus 130 may be a base station, e.g. a Node B, enhanced or evolved NodeB (eNB), a home eNode B (HeNB), an access point (AP), an IEEE 802.11 based access point, a femto node, a femto base station, or any other equipment belonging to the network infrastructure of the radio system, and implementing the radio communication interface with the terminal.
However, the second apparatus 130 may also be interpreted as a circuitry implementing the required functionality within the base station. As was explained, the second apparatus 130 creates 138 the reverse scheduling, causes 140 transmission of the reverse scheduling, and causes 142 data transmission with the reverse scheduling.
If the second apparatus 130 is the base station, then it will also comprise the equipment needed for the communication such equipment including at least one radio transceiver with all the required hardware and software. On the other hand, if the second apparatus 130 is the circuitry, then it will not necessarily comprise the radio transceiver(s) etc. but only interfaces enabling communication with such equipment implementing the communication with the terminal, for example. The second apparatus 130 may be a wireless modem designed to be used in a base station, or another product requiring wireless communication capabilities.
The radio system may be any standard/non-standard/proprietary system that supports described kind of scheduling. In the present, such a system is evolved universal terrestrial radio access (E-UTRA), also known as long term evolution (LTE) for example, or their recent LTE-Advanced versions (LTE-A). However, the example embodiments are not restricted thereto, but may be applicable to other suitable radio systems (in their present forms and/or in their evolution forms), such as universal mobile telecommunications system (UMTS) radio access network (UTRAN or EUTRAN), a system based on International Mobile Telecommunication (IMT) standard or any one of its evolution versions (e.g. IMT-Advanced), wireless local area network (WLAN) based on IEEE (Institute of Electrical and Electronics Engineers) 802.11 standard or its evolution versions (IEEE 802.11ac), worldwide interoperability for microwave access (WiMAX), Wi-Fi, 3GPP, Bluetooth®, personal communications services (PCS) and systems using ultra-wideband (UWB) technology. In at least some of the embodiments, the radio access technology uses network controlled resource scheduling.
Furthermore, the radio system 202 may comprise a Home eNodeB (HeNB) 206 (=base station) that may also interface with the a-GW 210. The HeNB 206 provides LTE radio coverage for the UE 200 by incorporating the capabilities of the eNB 204. As the flat architecture of the LTE 202 is not optimized for a very large number of HeNBs 206, a HeNB gateway 208 may be used to hide the large number of the HeNBs 206 from the a-GW 210.
In a cellular radio system, such as the one illustrated in
Additionally, the base station may be a wireless access point of a local area network. Some example embodiments cover use in a macro cell cellular network, a cellular network having hierarchies of different cell sizes (macro, micro, pico, femto), heterogeneous networks, enterprise LAN, public hotspot networks, home networks, small enterprises, home offices, and public houses.
Throughout this application, the terms base station and terminal are used consistently. It should be noted, however, that in some cases these network elements might also be known with other names. The basic difference between these two network elements is that the base station belongs to the network infrastructure, whereas the terminal belongs to the user of the system. As the general structure of the radio system, as well as the structures and functions of the network elements are well known in the art, their general structure will not be further described here, but the reader is advised to consult numerous textbooks and standards of the wireless telecommunications, such as 3GPP TS 36.XXX series.
In
Accordingly, the reverse scheduling may further comprise information indicating that the at least part of the subframes is not used in at least one of the following subframes utilized in the radio data transmission between the terminal 300, 200 and the base station 400, 204/206. Additionally, or alternatively, the reverse scheduling may further comprise information indicating that the at least part of the subframes is not used until further notice in the radio data transmission between the terminal 300, 200 and the base station 400, 204/206.
The reverse scheduling may further comprise information indicating that at least a part of downlink shared channels and/or a part of downlink control channels is not utilized for the radio data transmission from the base station 400, 204/206 to the terminal 300, 200. Additionally, or alternatively, the reverse scheduling may further comprise information indicating that at least a part of uplink shared channels and/or a part of uplink control channels is not utilized for the radio data transmission from the terminal 300, 200 to the base station 400, 204/206.
As the reverse scheduling indicates that at least a part of subframes is not utilized for radio data transmission, such subframes may be denoted as blank or almost blank subframes. As explained with reference to
Besides using reverse scheduling for cancellation of already allocated resources, it may be indicated that a subframe is almost blank subframe although no actual resources have been allocated to a certain terminal. Note that the terminal may otherwise transmit e.g. control data, HARQ (hybrid automatic repeat request) retransmissions or random access preambles. Similarly, the base station may normally transmit synchronization channels etc. in downlink unless muted. If downlink channels are muted, it may be beneficial for the terminal to know when downlink channels are not present.
The reverse scheduling may be in at least one of the following formats: downlink control information, and/or resource indication value. However, the list of the formats in non-exhaustive and other suitable formats may also be utilized, depending on the radio system and its various requirements.
As illustrated in
A terminal 300, 200 may occasionally transmit on uplink channels when no uplink grant is given. This happens e.g. in case of random access preambles, hybrid automatic repeat request (HARQ) retransmissions and acknowledgements, scheduling requests and channel quality indication (CQI) reports. Without the described reverse scheduling, the base station 400, 204/206 has limited or no means to prevent this from happening.
On the other hand, the base station 400, 204/206 may not switch off downlink signal without notifying the terminals since synchronization, channel estimation and tracking algorithms running on the terminals may expect that synchronization and reference signals transmitted by the base station are present at all times.
The base station 400, 204/206 may schedule resources to the terminals with fair or less fair scheduling algorithms, but there is no technology in use, except the described reverse scheduling, which would ease and allow rapid control of the interference for the terminals in bad radio conditions. In general, interference is minimized with network planning but once the network is deployed interference control mechanisms are limited. In LTE and successor technologies resources to the terminals may be scheduled for each one millisecond subframe separately or semi-persistent scheduling (SPS) may be used for longer semi-static allocations.
The base station 400, 204/206 may utilize existing scheduling mechanisms to create either uplink or downlink reverse allocations to the terminals. Such changes are easily pinpointed to the existing products, i.e. the embodiments are readily implemented by the skilled person. This allocation explicitly notifies those one millisecond subframe periods when not to transmit anything on uplink channels or when no downlink signal is present. With this mechanism, network mutes selected terminals or signals to the terminals that the downlink is muted on the cell in certain subframe or pattern of subframes. Also certain already allocated semi-persistent allocations may be cancelled without removing the whole semi-persistent allocation. This may provide a way to quickly and precisely eliminate intercell and/or terminal-to-terminal interference temporarily on selected areas.
Technical implementation for LTE and successor technologies is considered here. For delivering reverse allocations or semi-persistent allocations to terminals, current scheduling mechanisms may be used. Some parameter in downlink control information (DCI) format may be used for indicating that reverse allocation is indicated instead of normal allocation.
For example, resource indication values (RIV) that are normally used for indicating allocated frequency resources contain certain amount of invalid unused values when resource allocation type 2 is used. Utilizing some of these invalid values reverse allocation may be notified to the terminal by using downlink control information (DCI) format 1A for downlink and DCI format 0 for uplink. These DCI formats may be used in every transmission mode and with every RNTI (Radio Network Temporary Identifier) type which provides universal and flexible solution. Further bits in the DCI block may be used for signaling the subframe pattern and possibly other relevant parameters.
At least some of the example embodiments may give more flexibility for network to schedule terminals and control interference. Certain terminals or cells may be muted for certain short time periods dynamically and with very short delay. This muting may be utilized e.g. for improving cell edge user conditions at least for short periods if interfering cells or/and terminals may be muted. Also, in future LTE-Advanced scenarios where there might be smaller hotspot cells inside bigger cells in heterogeneous networks, reverse allocations may be utilized for creating temporary and efficient muting patterns for certain areas dynamically. In cellular networks with high mobility and changing number of terminals, network may easily and rapidly respond to current situation and take also terminals with worse radio conditions more fairly into account.
With reference to
The user interface 330 may comprise user interface circuitry (such as integrated circuits and devices such as touch-screen, keypad etc.) and user interface computer program code configured to facilitate user control of at least some functions of the terminal 300. The battery 332 may be an electrical battery including electrochemical cells that convert stored chemical energy into electrical energy.
The system clock 328 constantly generates a stream of electrical pulses, which cause the various transferring operations within the terminal 300 to take place in an orderly manner and with specific timing.
The transceiver 324 may implement a telecommunications connection between the terminal 300 and some other device. A wireless connection may be implemented with a wireless transceiver operating according to the earlier mentioned standards, such as the LTE, WLAN or any other suitable standard/non-standard wireless communication means. The transceiver 324 may comprise standard well-known components such as an amplifier, filter, frequency-converter, (de)modulator, encoder/decoder circuitries, and one or more antennas.
Additionally, the terminal 300 may communicate with other devices through its memory, e.g. the data 304 may have been brought into the non-volatile memory 302 via a memory device (such as a memory card, an optical disk, or any other suitable non-volatile memory device).
The term ‘processor’ 102 refers to a device that is capable of processing data. Depending on the processing power needed, the terminal 100 may comprise several (parallel) processors 102. The processor 102 may comprise an electronic circuitry. When designing the implementation, a person skilled in the art will consider the requirements set for the size and power consumption of the terminal 300, the necessary processing capacity, production costs, and production volumes, for example. The electronic circuitry of the processor 102 and the memory 104 may comprise one or more logic components, one or more standard integrated circuits, one or more application-specific integrated circuits (ASIC), one or more microprocessors, one or more processors with accompanying digital signal processors, one or more processors without accompanying digital signal processors, one or more special-purpose computer chips, one or more field-programmable gate arrays (FPGA), one or more controllers, hardware-only circuit implementations, such as implementations in only analogue and/or digital circuitry, combinations of circuits and software (and/or firmware), such as (as applicable): a combination of processor(s) or portions of processor(s)/software including digital signal processor(s), software, and memory(ies) that work together to cause an apparatus to perform various functions, circuits, such as a microprocessor(s) or a portion of a microprocessor(s), that require software or firmware for operation, even if the software or firmware is not physically present, and/or other suitable electronic structures. This definition of ‘circuitry’ applies to all uses of this term in this application. As a further example, as used in this application, the term “circuitry” would also cover an implementation of merely a processor (or multiple processors) 102 or portion of a processor 102 and its (or their) accompanying software and/or firmware. The term “circuitry” would also cover, for example and if applicable to the particular element, a baseband integrated circuit or applications processor integrated circuit for a user equipment.
The microprocessor 102 may implement functions of a central processing unit (CPU) on an integrated circuit. The CPU is a logic machine executing a computer program 334, which comprises computer program code 106. The program code 106 may be coded as a computer program using a programming language, which may be a high-level programming language, such as C, or Java, or a low-level programming language, such as a machine language, or an assembler. The program code 106 may also be hard-wired, e.g. if the processor 102 is implemented as an ASIC, the program code is implemented as blocks developed and implemented by appropriate ASIC development tools.
The CPU may comprise a set of registers 318, an arithmetic logic unit (ALU) 320, and a control unit (CU) 322. The control unit 322 is controlled by a sequence of program code 106 transferred to the CPU from the working memory 104. The control unit 322 may contain a number of microinstructions for basic operations. The implementation of the microinstructions may vary, depending on the CPU design. The processor 102 may also have an operating system (a general purpose operating system, a dedicated operating system of an embedded system, or a real-time operating system, for example), which may provide the computer program 334 with system services. Examples of operating systems include: MeeGo, Symbian, Android, iOS, RIM Blackberry OS, Windows Mobile, Linux, bada, Maemo etc.
There may be three different types of buses between the working memory 104 and the processor 102: a data bus 310, a control bus 312, and an address bus 314. The control unit 322 uses the control bus 312 to set the working memory 104 in two states, one for writing data into the working memory 104, and the other for reading data from the working memory 104. The control unit 322 uses the address bus 314 to send to the working memory 104 address signals for addressing specified portions of the memory 104 in writing and reading states. The data bus 310 is used to transfer data 308 from the working memory 104 to the processor 102 and from the processor 102 to the working memory 104, and to transfer the program code 106 from the working memory 104 to the processor 102.
The working memory 104 may be implemented as a random-access memory (RAM), where the information is lost after the power is switched off. The RAM is capable of returning any piece of data in a constant time, regardless of its physical location and whether or not it is related to the previous piece of data.
The non-volatile memory 302 retains the stored information even when not powered. Examples of non-volatile memory include read-only memory (ROM), flash memory, magnetic computer storage devices such as hard disk drives, and optical discs. As is shown in
An example embodiment provides a computer-readable medium 332 comprising computer program code which, when loaded into the terminal 300, cause the apparatus to perform the required operations, illustrated as a method with reference to
There are many ways to structure the program 334. The operations of the program may be divided into functional modules, sub-routines, methods, classes, objects, applets, macros, widgets, design blocks etc., depending on the software design methodology and the programming language used. In modern programming environments, there are software libraries, e.g. compilations of readymade functions, which may be utilized by the program for performing a wide variety of standard operations.
With reference to
The transceiver 408 may implement a telecommunications connection between the base station 400 and the terminal 300. A wireless connection may be implemented with a wireless transceiver operating according to the earlier mentioned standards, such as the LTE, or any other suitable standard/non-standard wireless communication means.
The power source 406 may be an independent power source, such as an electrical battery, a solar cell, or other means of generating energy, or it may be dependent from the outside world (of the base station 400), such as a power supply connected to a wall outlet (mains).
Data stored in the non-volatile memory 302 is now denoted with reference numeral 404, and data stored in the working memory 134 by reference numeral 406.
An example embodiment provides a computer-readable medium 332 comprising computer program code which, when loaded into the base station 400, cause the apparatus to perform the required operations, illustrated as a method with reference to
The reverse scheduling may be a feature that is always on. Alternatively, the reverse scheduling may need configuration and/or enablement: in
The need for subframe muting may be detected 818 in RRC layer 800 and/or MAC layer 802 of the base station 300. The need for subframe muting may be detected by all feasible ways, by mechanisms related to interference co-ordination, for example.
The MAC layer 802 of the base station 300 transmits 820 the reverse allocation to the MAC layer 808 of the terminal 300. After a delay 822, the subframe may be muted 824, which affects the functioning of the PHY layers 804, 806 and MAC layers 802, 808. Note that one millisecond may be a minimum reaction time in some cases (such as in the LTE). It may also be defined longer for uplink if the terminal 400 needs more time to cancel its uplink transmission. In normal uplink allocations, if allocation is received in subframe N, then uplink transmission shall happen in subframe N+4. Consequently, this N+4 rule may also be reasonable for uplink reverse allocations. Additionally, there is some timing advance in uplink transmissions, which makes one millisecond reaction time challenging for uplink. In downlink direction, one millisecond works fine. Reverse allocation may be defined to one or several subframes long and non-persistent or semi-persistent. In
In order to utilize the shared channel resources efficiently, a scheduling function may be used in the MAC layer, for which the scheduler operation, signaling of scheduler decisions and measurements to support scheduler operation are determined. The scheduler may take into account of the traffic volume and the quality of service (QoS) requirements of each terminal and associated radio bearers. Resource assignment may comprise physical resource blocks (PRB), modulation and coding schemes (MCS), and additional information (allocation time, allocation repetition factor). Carrier aggregation may also be applied, in which transmissions between the terminal and the base station are aggregated on multiple carriers (on same frequency band, on different frequency bands, and/or with different radio access technologies). Note that as the reverse scheduling signaling is implemented at physical layer and/or MAC layer, the reverse scheduling may react fast to the ever-changing radio environment and its circumstances. The reverse scheduling may thus be implemented in a dynamic and explicit fashion, meaning that the processing time is kept short and the processing requirements relatively low.
Next, example embodiments of a method will be described with reference to
In the embodiment of
In 1002, a reverse scheduling received by the terminal from the base station is obtained.
The reverse scheduling may further comprise information indicating that the at least part of the subframes is not used in at least one of the following subframes utilized in the radio data transmission between the terminal and the base station. Additionally, or alternatively, the reverse scheduling may further comprise information indicating that the at least part of the subframes is not used until further notice in the radio data transmission between the terminal and the base station.
The reverse scheduling may further comprise information indicating that at least a part of downlink shared channels and/or a part of downlink control channels is not utilized for the radio data transmission from the base station to the terminal. Additionally, or alternatively, the reverse scheduling may further comprise information indicating that at least a part of uplink shared channels and/or a part of uplink control channels is not utilized for the radio data transmission from the terminal to the base station.
In 1010, changes to the semi-persistent scheduling are caused on the basis of the reverse scheduling, thereby arriving at a reversed semi-persistent scheduling.
In 1004, a radio data transmission between the terminal and the base station is caused to operate according to the reversed semi-persistent scheduling.
The method ends in 1006.
Next, example embodiments of a method will be described with reference to
In the embodiment of
In 1112, a transmission of the semi-persistent scheduling is caused from the base station to the terminal.
In 1102, a reverse scheduling is created for the terminal.
The reverse scheduling may further comprise information indicating that the at least part of the subframes is not used in at least one of the following subframes utilized in the radio data transmission between the terminal and the base station. Additionally, or alternatively, the reverse scheduling may further comprise information indicating that the at least part of the subframes is not used until further notice in the radio data transmission between the terminal and the base station.
The reverse scheduling may further comprise information indicating that at least a part of downlink shared channels and/or downlink control channels is not utilized for the radio data transmission from the base station to the terminal. Additionally, or alternatively, the reverse scheduling may further comprise information indicating that at least a part of uplink shared channels and/or uplink control channels is not utilized for the radio data transmission from the terminal to the base station.
In 1104, a transmission of the reverse scheduling is caused from the base station to the terminal.
In 1114, changes to the semi-persistent scheduling are caused on the basis of the reverse scheduling, thereby arriving at a reversed semi-persistent scheduling.
In 1106, a radio data transmission between the terminal and the base station radio is caused to operate according to the reversed semi-persistent scheduling.
The method ends in 1108.
The present invention is applicable to radio systems defined above but also to other suitable telecommunication systems. The protocols used, the specifications of radio systems, their base stations, and terminals develop rapidly. Such development may require extra changes to the described example embodiments. Therefore, all words and expressions should be interpreted broadly and they are intended to illustrate, not to restrict, the example embodiments. It will be obvious to a person skilled in the art that, as technology advances, the inventive concept can be implemented in various ways. The invention and its example embodiments are not limited to the examples described above but may vary within the scope of the claims.
