Determine the reference signal location

Abstract

The present invention relates to determining reference signal positions. To determine the reference signal positions, the method 500 determines a number of transmission time intervals (TTIs) in a scheduled transmission of a plurality of TTIs. The method 500 further determines one or more reference signal positions 145 based on the number of TTIs.

Description

[0001] This application is a divisional application of an application which entered the Chinese national phase on December 28, 2018, with PCT application number PCT / US2017 / 046806, international application date August 14, 2017, Chinese application number 201780040536.8, and invention name “Determining Reference Signal Position”. Technical Field

[0002] The subject matter disclosed herein relates to reference signal locations and, more particularly, to determining reference signal locations. Background Art

[0003] Description of Related Art

[0004] In Long Term Evolution (LTE) and other wireless communication standards, communication delays can be reduced by adopting a shorter minimum transmission time interval (TTI). Summary of the invention

[0005] A method for determining a reference signal location is disclosed. The method determines a number of transmission time intervals (TTIs) in a scheduled transmission of multiple transmission time intervals (TTIs). The method further determines one or more reference signal locations based on the number of TTIs. A device also performs the functions of the method. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] A more particular description of the embodiments briefly described above will be presented with reference to specific embodiments illustrated in the accompanying drawings. Understanding that these drawings depict only some embodiments and therefore should not be considered limiting of scope, the embodiments will be described and explained in additional detail and in detail through the use of the accompanying drawings, in which:

[0007] Figure 1 is a schematic block diagram illustrating one embodiment of a communication system;

[0008] Figure 2A is a schematic block diagram illustrating one embodiment of a subframe;

[0009] Figure 2B is a schematic block diagram illustrating an alternative embodiment of a subframe;

[0010] Figure 2C is a schematic block diagram illustrating one embodiment of a resource block;

[0011] Figure 2D is a schematic block diagram illustrating one embodiment of a message;

[0012] Figures 3A to 3H is a schematic block diagram illustrating an embodiment of reference signal locations within a subframe;

[0013] Fig. 3Iis a schematic block diagram illustrating one embodiment of allocating data in a scheduled transmission time interval (TTI);

[0014] Figure 4 is a schematic block diagram illustrating one embodiment of a computer;

[0015] Figure 5A is a schematic flow chart illustrating an embodiment of a method for determining a reference signal position;

[0016] Figure 5B is a schematic flow chart illustrating one embodiment of a pattern assignment method;

[0017] Figure 5C is a schematic flow chart illustrating one embodiment of a reference signal presence / absence position determination method;

[0018] Figure 5D is a schematic flow chart illustrating an embodiment of a reference signal port determination method; and

[0019] Figure 5E is a schematic flow chart illustrating an embodiment of a method for determining a reference signal number. DETAILED DESCRIPTION

[0020] As will be appreciated by those skilled in the art, aspects of the embodiments may be embodied as systems, methods, or program products. Thus, the embodiments may take the form of a fully hardware embodiment, a fully software embodiment (including firmware, resident software, microcode, etc.), or an embodiment that combines software and hardware aspects (generally, they may all be referred to herein as "circuits," "modules," or "systems"). In addition, the embodiments may take the form of a program product contained in one or more computer-readable storage devices storing machine-readable code, computer-readable code, and / or program code (hereinafter referred to as code).

[0021] The storage device may be tangible, non-temporary, and / or non-transmitting. The storage device may not contain signals. In a particular embodiment, the storage device only uses signals for accessing the code. Many functional units described in this specification have been labeled as modules to more particularly emphasize their implementation independence. For example, a module may be implemented as a hardware circuit, which includes a custom VLSI circuit or gate array, a ready-made semiconductor such as a logic chip, a transistor, or other discrete components.

[0022] Modules may also be implemented in programmable hardware devices, such as field programmable gate arrays, programmable array logic, programmable logic devices, etc. Modules may also be implemented in code and / or software so that they are executed by various processors. For example, the identification module of a code may include one or more physical or logical executable code blocks, which may be organized into objects, processes, or functions. Nevertheless, the executable file of the identification module does not need to be physically located in one place, but may include instructions that are very different and are stored in different locations, which include the module when logically combined and achieve the intended purpose of the module.

[0023] In fact, the module of code can be a single instruction or many instructions, and can even be distributed on a plurality of different code segments, distributed between different programs and distributed in a plurality of memory devices.Similarly, in this article, operating data can be identified and illustrated in the module, and can be embodied in any suitable form and be organized in the data structure of any suitable type.Operational data can be collected into a single data set, or can be distributed in different locations (comprising being distributed in different computer-readable storage devices).When the part of module or module is implemented in software, the software part is stored in one or more computer-readable storage devices.

[0024] Any combination of one or more computer readable media may be utilized. The computer readable medium may be a computer readable storage medium. The computer readable storage medium may be a storage device storing code. The storage device may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, holographic, micromechanical, or semiconductor system, device, or apparatus, or any suitable combination of the foregoing.

[0025] More specific examples of storage devices (a non-exhaustive list) may include the following: an electrical connection with one or more wires, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above. In the context of this article, a computer-readable storage medium can be any tangible medium that can contain or store a program for use by or in conjunction with an instruction execution system, device, or apparatus.

[0026] The code for performing the operation of the embodiment can be written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Python, Ruby, Java, Smalltalk, C++, and conventional procedural programming languages ​​such as "C" programming languages, and / or machine languages ​​such as assembly languages. The code can be executed entirely on the user's computer, partially on the user's computer, as an independent software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In the latter case, the remote computer can be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or the connection can be made with an external computer (e.g., by using the Internet of an Internet service provider).

[0027] Throughout this specification, references to "one embodiment," "an embodiment," or similar language mean that a particular feature, structure, or characteristic described in conjunction with that embodiment is included in at least one embodiment. Therefore, unless expressly stated otherwise, throughout this specification, the phrases "in one embodiment," "in an embodiment," and similar language may, but do not necessarily, refer to the same embodiment, but rather mean "one or more but not all embodiments." Unless expressly stated otherwise, the terms "include," "comprises," "has," and variations thereof mean "including but not limited to." Unless expressly stated otherwise, an enumerated list of items does not imply that any or all of the items are mutually exclusive. Unless expressly stated otherwise, the terms "one," "an," and "the" also mean "one or more."

[0028] In addition, the features, structures or characteristics of the described embodiments can be combined in any suitable manner. In the following description, numerous specific details are provided, such as programming examples, software modules, user selections, network transactions, database queries, database structures, hardware modules, hardware circuits, hardware chips, etc., in order to provide a thorough understanding of the embodiments. However, those skilled in the relevant art will appreciate that embodiments can also be practiced without one or more of these specific details, or using other methods, components, materials, etc. In other instances, known structures, materials or operations are not shown or described in detail to avoid blurring the aspects of the embodiments.

[0029] The aspects of the embodiments will be described below with reference to the schematic flow chart and / or schematic block diagram of the method, device, system and program product according to the embodiment.It is to be understood that the individual frames of the schematic flow chart and / or schematic block diagram and the combination of the frames in the schematic flow chart and / or schematic block diagram can be implemented by code.These codes can be provided to the processor of a general-purpose computer, a special-purpose computer or other programmable data processing device to produce a machine, so that when the instruction is executed via the processor of a computer or other programmable data processing device, the instruction creates a part for implementing the function / action specified in the frame or multiple frames in the schematic flow chart and / or schematic block diagram.

[0030] The code may also be stored in a storage device capable of directing a computer, other programmable data processing equipment or other apparatus to function in a specific manner, so that the instructions stored in the storage device produce an article of manufacture, which includes instructions for implementing the functions / actions specified in a box or multiple boxes in the schematic flowchart and / or schematic block diagram.

[0031] The code may also be loaded onto a computer, other programmable data processing device or other apparatus to enable a series of operational steps to be performed on the computer, other programmable data processing device or other apparatus to produce a computer-implemented process, so that the code executed on the computer or other programmable device provides a process for implementing the functions / actions specified in a box or multiple boxes in the flowchart and / or block diagram.

[0032] The schematic flow charts and / or schematic block diagrams in the figures illustrate the architecture, functionality and operation of possible implementations of the devices, systems, methods and program products according to various embodiments. In this regard, each box in the schematic flow charts and / or schematic block diagrams may represent a module, segment or portion of code, including one or more executable instructions of the code for implementing the specified (multiple) logical functions.

[0033] It should also be noted that in some alternative implementations, the functions indicated in the blocks may not occur in the order indicated in the figure. For example, two blocks shown in succession may in fact be executed substantially in parallel, or the blocks may sometimes be executed in reverse order, depending on the functionality involved. Other steps and methods that are equivalent in function, logic or effect to one or more blocks or portions thereof of the illustrated figure may be envisioned.

[0034] Although various arrow types and line types have been adopted in flow chart and / or block diagram, these arrow types and line types are understood to not limit the scope of corresponding embodiment.In fact, some arrows or other connectors can be used to indicate the logical flow of depicted embodiment only.For example, arrows can indicate the waiting or monitoring period of the unspecified duration between the enumeration steps of depicted embodiment.It should also be noted that the combination of each frame of block diagram and / or flow chart and the frame in block diagram and / or flow chart can be implemented by the combination of hardware-based system or special-purpose hardware and code of the special-purpose of performing specified function or action.

[0035] The description of the elements in each figure can refer to the elements of the previous figure. In all figures, the same number represents the same element, including alternative embodiments of the same element.

[0036] Figure 1 1 is a schematic block diagram illustrating an embodiment of a communication system 100. The system 100 includes a base station 105, a network 115, and user equipment 110a-c. The base station 105 can communicate with the user equipment 110a-c through the network 115. The base station 105 can be an evolved Node B (eNB) long term evolution (LTE) base station. The user equipment 110 can be a mobile phone, a machine type communication (MTC) device, a tablet computer, a laptop computer, and an embedded communication device in a car, a self-service terminal, an appliance, etc. The network 115 can be a mobile phone network. Alternatively, the network 115 can be a wide area network, a wireless network, or a combination thereof.

[0037] The base station 105 may transmit data to the user equipment 110 via a scheduled transmission. The scheduled transmission may include a plurality of transmission time intervals (TTIs). In one embodiment, the TTI is a shortened TTI (sTTI), although for simplicity, all TTIs are referred to as TTIs regardless of length. The TTI may be organized in subframes, each subframe or physical resource block (PRB) including a plurality of symbols, as will be described below.

[0038] The physical downlink control channel (PDCCH) may carry downlink control information (DCI), such as information about reference signals. The reference signals may encode information about the data to be conveyed in the scheduled transmission and information about the resources that the user equipment 110a-c should use to transmit uplink data.

[0039] The delay of the network 115 can be reduced by shortening the TTI in the subframe. Unfortunately, as the TTI is shortened, the overhead caused by the reference signal increases. The embodiments described herein reduce the overhead of the reference signal by sending the reference signal in a subset of the TTI, as will be described below. The embodiments can indirectly transmit the reference signal position in a subset of the TTI by using the number of TTIs, as well as the resource assignment message, the parameters received from the higher layer, the subframe index, the time interval between the TTIs, and the time division duplex (TDD) configuration for transmitting the reference signal position. The reference signal can then be transmitted in a reduced set of reference signal positions. Therefore, the reference signal density is reduced, thereby reducing the data transmission delay of the system 100.

[0040] Figure 2A 1 is a schematic block diagram illustrating one embodiment of a subframe 125. In one embodiment, a subframe 125 transmits data in a time interval of 1 millisecond (ms). Each subframe 125 may include a plurality of resource blocks 130, each resource block 130 occupying a unique combination of modulation frequency and time interval within the subframe 125.

[0041] Figure 2B 1 is a schematic block diagram illustrating an alternative embodiment of a subframe 125. For simplicity, the subframe 125 is depicted as having seven TTIs 135, each TTI having two orthogonal frequency division multiplexing (OFDM) symbols. Each combination of a TTI 135 and a subband 140 represents a resource block 130. A subframe 125 or other data organization may include any number of resource blocks 130, TTIs 135, and / or subbands 140.

[0042] For a particular TTI length (e.g., a 2-symbol sTTI 135), the user equipment 110 may assume that the resource block group (RBG) size in the sTTI 135 containing cell-specific reference signal (CRS) resource elements (REs) (or any other signal / channel) may be a function, such as a scaling factor of the RBG size in the sTTI 135 not containing CRS REs (or any other signal / channel). For example, if the RBG size in a CRS-free sTTI 135 is 5 resource blocks 130, then the RBG size in a CRS-type sTTI 135 is 6 resource blocks 130.

[0043] The RBG size of the sTTI 135 including CRS (or other reference symbols, such as positioning, channel state information reference signal (CSI-RS), etc., or other channels) and the scaling factor of the sTTI 135 not including such a signal can be configured by a higher layer or by the physical layer, for example, a possible set of scaling factors can be {1, 1.2}. An offset can be used instead of a scaling factor. For example, an offset of "1" may indicate that the RBG size in the sTTI 135 including CRS (or other reference symbols, such as positioning, CSI-RS, etc., or other channels) is one RB larger than the RBG size in the sTTI 135 without CRS (or other reference symbols, such as positioning, CSI-RS, etc., or other channels). When the RBG size is fixed and not signaled in a multi-TTI grant, the offset can be applied even if a single TTI grant is applied. It can be configured by higher layer signaling (such as radio resource control (RRC)) or can be fixed in the specification.

[0044] In one embodiment, if there is an sTTI 135 with a scaled or offset RBG size relative to the RBG size of other scheduled sTTIs 135 in a set of multi-TTI 135 schedulings of sTTIs 135 (where only a subset of sTTIs 135 contain reference signals 155), then the same precoder is assumed to be applied to all resource blocks 130 in the RBGs (regardless of RBG size) in all sTTIs 135 that benefit from the same reference signal 155 (DMRS) symbols in terms of reference signal usage from other sTTIs 135. This approach enables the eNB to flexibly utilize resources in sTTIs 135 without CRS to schedule other user equipment 110.

[0045] Figure 2C 1 is a schematic block diagram illustrating one embodiment of a resource block 130. In the depicted embodiment, the resource block 130 includes a reference signal location 145. A reference signal 155 may be transmitted in the reference signal location 145. The reference signal 155 may encode information such as DCI about the data to be transmitted in the scheduled transmission and information about the resources that the user equipment 110 should use to transmit uplink data. The presence or absence of the reference signal 155 may enable some unused resources, including TTIs 135 where the reference signal 155 is not present to be used for data transmission.

[0046] Figure 2D1 is a schematic block diagram illustrating one embodiment of a message. A resource assignment message 160, a scheduled transmission 165, and an acknowledgement message 170 are shown. The resource assignment message 160 may include downlink assignment information and / or uplink grant and may be transmitted to the user equipment 110 via the PDCCH. The scheduled transmission 165 may include one or more subframes 125. The acknowledgement message 170 may acknowledge receipt of data in the scheduled transmission 165.

[0047] For a particular TTI length (e.g., a 2-symbol sTTI 135), the user equipment 110 may assume that the resource block group (RBG) size in the sTTI 135 containing CRS REs (or any other signal / channel) may be a function, such as a scaling factor of the RBG size in the sTTI 135 not containing CRS REs (or any other signal / channel). For example, if the RBG size in a CRS-free sTTI 135 is 5 resource blocks 130, then the RBG size in a CRS-type sTTI is 6 resource blocks 130.

[0048] The scaling factor of the RBG size of the sTTI 135 containing CRS (or other reference symbols, such as positioning, CSI-RS, etc., or other channels) and the sTTI 135 not containing such a signal can be configured by a higher layer or by the physical layer, for example, a possible set of scaling factors can be {1, 1.2}. An offset can be used instead of a scaling factor. For example, an offset of "1" can represent a resource block 130 that is larger than the RBG size in the sTTI 135 including CRS (or other reference symbols, such as positioning, CSI-RS, etc., or other channels) than the RBG size in the sTTI 135 without CRS (or other reference symbols, such as positioning, CSI-RS, etc., or other channels). When the RBG size is fixed and not signaled in a multi-TTI grant, the offset can be applied even if a single TTI grant is applied. It can be configured by higher layer signaling (such as radio resource control (RRC)) or can be fixed in the specification.

[0049] In one embodiment, if there is an sTTI 135 with a scaled or offset RBG size relative to the RBG size of other scheduled sTTIs 135 in a set of multi-TTI 135 schedulings of sTTIs 135 (where only a subset of sTTIs 135 contain reference signals 155), then the same precoder is assumed to be applied to all resource blocks 130 in the RBGs (regardless of RBG size) in all sTTIs 135 that benefit from the same DMRS symbol in terms of reference signal usage from other sTTIs 135. This approach enables the eNB to flexibly utilize resources in sTTIs 135 without CRS to schedule other user equipment 110.

[0050] 3A to 3H 1 is a schematic block diagram illustrating an embodiment of a reference signal location at a predetermined TTI instance 135 of a plurality of TTIs 135 within a subframe 125. The predetermined TTI instance 135 is indicated below with cross-hatching. The illustrated reference signal location 145 is an example of a reference signal transmitted within the predetermined TTI instance 135, which is a subset of the plurality of TTIs 135 within the subframe 125, but is not limiting. The reference signal location 145 and the predetermined TTI instance 135 may be determined by calculation, table lookup, and / or one or more logic tests as will be described below.

[0051] The one or more reference signal locations 145 may be determined to be in predetermined TTI instances 135 of the plurality of TTIs 135. The number of predetermined TTI instances 135 and / or the number of predetermined TTI instances 135 may be less than the number of TTIs 135, wherein the reference signal 155 is present only in the predetermined TTI instances 135. In one embodiment, the one or more reference signal locations 145 may be determined to be in predetermined subband instances 140 of the predetermined TTI instances 135.

[0052] For simplicity, seven TTIs 135 and one or two subbands 140 are shown. However, embodiments may be practiced with reference signals 155 transmitted within other combinations of predetermined TTI instances 135 and predetermined subband instances 140.

[0053] Figure 3A One reference signal location 145 is shown within a predetermined TTI instance 135, which is the first TTI 135a of a given subband 140 of a subframe 125. In alternative embodiments, the predetermined TTI instance 135 for the one reference signal location 145 may be any TTI 135a-g of a subframe 125.

[0054] Figure 3BTwo reference signal locations 145 are shown at two predetermined TTI instances 135 within a given subband 140 of a subframe 125. Although the two predetermined TTI instances 135 are depicted as first and third TTIs 135a / c, the two predetermined TTI instances 135 may be any TTIs 135a-g of a subframe 125.

[0055] Figure 3C Three reference signal locations 145 are shown at three predetermined TTI instances 135 within a given subband 140 of a subframe 125. The three predetermined TTI instances 135 are depicted as the first, third, and seventh TTIs 135a / c / g. However, the three predetermined TTI instances 135 may be any TTI 135a-g of the subframe 125. For example, Figure 3D Three reference signal locations 145 in the predetermined TTI instances 135 at the first, third and sixth TTIs 135a / c / f are shown. The predetermined TTI instances 135 may be periodic within the sub-band 140. Alternatively, the predetermined TTI instances 135 may be aperiodic within the sub-band 140.

[0056] Figure 3E One embodiment of reference signal positions 145 for two subbands 140a-b of a subframe 125 is shown. In one embodiment, the one or more reference signal positions 145 are determined to be in predetermined subband instances 140a-b of a predetermined TTI instance 135. For a subset of subbands 140 in the plurality of subbands 140, the pattern of presence and absence of reference signal positions 145 may be different between the respective subbands 140a-b. For example, the presence / absence pattern of reference signal positions 145 may be different for respective subbands 140 in a first set of subbands 140 and for respective subbands 140 in a second set of subbands 140, but the second set of subbands 140 may include at least one presence / absence pattern of reference signal positions 145 that is different from the first set of subbands 140.

[0057] In the depicted embodiment, each subband 140a-b includes a reference signal position 145 at a predetermined TTI instance 135 in a first TTI 135. However, the reference signal positions 145 may be allocated such that the predetermined TTI instance 135 for the reference signal position 145 is not located in a concurrent TTI 135. In one embodiment, the one or more reference signal positions 145 for the second predetermined subband instance 140b of the second predetermined TTI instance 135 are determined further based on the one or more reference signal positions 145 of the first predetermined subband instance 135 of the first predetermined TTI instance 145. For example, if the third TTI 135c is selected as the second predetermined TTI instance 135 for the first predetermined subband instance 140a, the second TTI 135b may be selected as the second predetermined TTI instance 135 for the second predetermined subband instance 140b based on selecting the third TTI 135c as the second predetermined TTI instance 135 for the first predetermined subband instance 140a.

[0058] In one embodiment, some of the predetermined TTI instances 135 may differ between one or more subbands 140 in the set of subbands 140. Additionally, all of the predetermined TTI instances 135 may differ between one or more subbands 140 in the set of subbands 140. In a particular embodiment, the number of predetermined TTI instances 135 may differ between one or more subbands 140 in the set of subbands 140. Table 1 shows additional examples of differences in predetermined TTI instances 135 between subbands 140, where TTI 135 index numbers are listed for each subband 140. This table is exemplary and not limiting.

[0059] Table 1

[0060] Predetermined TTI instance 135 for the first subband 140a The predetermined TTI instance 135 for the second subband 140b TTI: 1,3,5 TTI: 2,4,5 TTI: 1, 2, 4 TTI: 1,3,4,5 TTI: 2,4,6 TTI: 1,3,5,7

[0061] The predetermined TTI instances 135 may be periodic between the sub-bands 140. Alternatively, the predetermined TTI instances 135 may be aperiodic between the sub-bands 140.

[0062] In one embodiment, if a single transport block is sent across two or more resource block groups (or subbands), the benefit of using different reference signal presence / absence patterns (or different predetermined TTIs) for different resource block groups (or subbands) may become smaller, depending on factors such as the coding rate associated with the transport block.

[0063] Figure 3FOne embodiment of reference signal locations 145 for two subbands 140a-b of a subframe 125 is shown. In the depicted embodiment, each subband 140a-b includes a reference signal location 145 at a predetermined TTI instance 135 in a first TTI 135a. However, the reference signal locations 145 may be allocated such that the predetermined TTI instances 135 for subsequent reference signal locations 145 are not located in concurrent TTIs 135. In the depicted embodiment, the predetermined TTI instances 135 for the first subband 140a are at the first, third, and seventh TTIs 135a / c / g, while the predetermined TTI instances 135 for the second subband 140b are at the first, second, and sixth TTIs 135a / c / f.

[0064] Figure 3G Four reference signal locations 145 are shown at four predetermined TTI instances 135 within a given subband 140 of a subframe 125. The four predetermined TTI instances 135 are depicted as the first, third, fifth, and seventh TTIs 135a / c / e / g.

[0065] Figure 3H Three reference signal locations 145 are shown at three predetermined TTI instances 135 within a given subband 140 of a subframe 125. The three predetermined TTI instances 135 are depicted as the first, fourth, and seventh TTIs 135a / d / g.

[0066] Fig. 3I 1 is a schematic block diagram illustrating one embodiment of allocating data 150 in scheduled TTIs 135. Some scheduled TTIs 135 may include reference signals 155 as well as data. In the depicted embodiment, data 150 for three user equipment instances 110a-c are allocated to two subbands 140 of a subframe 125. First data 150a for a first user equipment instance 110a is allocated to the first, second, third, fourth, and sixth TTIs 135a / b / c / d / f of the first subband 140a. Second data 150b for a second user equipment instance 110b is allocated to the fifth and seventh TTIs 135e / g of the first subband 140a and the first, second, third, and fourth TTIs 135a-d of the second subband 140b. Additionally, third data 150c for a third user equipment instance 110c is allocated to the fifth, sixth, and seventh TTIs 135e-g of the second subband 140b.

[0067] In one embodiment, the first TTI 135a may require more reference signal positions 145 to achieve a particular channel estimation performance, and subsequent TTIs 135 may require fewer reference signal positions 145 because, if the channel is not changing rapidly (such as in low Doppler conditions), the subsequent TTIs 135 can reuse the reference signal 135 of the previously scheduled TTI 135.

[0068] Figure 4 4 is a schematic block diagram illustrating one embodiment of a computer 400. The computer 400 may be included in the user equipment 110 and / or the base station 105. In the depicted embodiment, the computer 400 includes a processor 405, a memory 410, and communication hardware 415. The memory 410 may include a semiconductor memory device, a hard disk drive, an optical memory device, a micromechanical memory device, or a combination thereof. The memory 410 may store code and data. The processor 405 may execute code and process data.

[0069] The communication hardware 415 may include one or more transmitters and one or more receivers for transmitting data 150 between the base station 105 and the user equipment 110 over the network 115. Each transmitter and / or receiver may include one or more antenna ports.

[0070] Figure 5A is a schematic flow chart illustrating an embodiment of a reference signal position determination method 500. The reference signal position determination method 500 may determine one or more reference signal positions 145 and a predetermined TTI instance 135 and may transmit a reference signal 155 in the predetermined TTI instance 135. The method 500 may be performed by a base station 105, a user equipment 110, or a combination thereof. In addition, the method 500 may be performed by a processor 405 of the base station 105 and / or the user equipment 110.

[0071] The method 500 begins, and in one embodiment, the processor 405 determines 505 a number of signal reference locations 145 based on the number of a plurality of TTIs 135 for a scheduled transmission 165. Additionally, the number of signal reference locations 145 may be determined 505 based on the number of a plurality of TTIs 135 and one or more of a subframe index, a time interval between TTIs 135 in the scheduled transmission 165, a subframe size, and a TDD configuration for the scheduled transmission 165.

[0072] In one embodiment, processor 405 of base station 105 determines 510 reference signal position 145 for reference signal 155 transmitted in subframe 120 of scheduled transmission 165. As used herein, "determine" means to calculate, look up, and / or make a logical decision based on one or more inputs.

[0073] The processor 405 may determine 505 the number of signal reference positions 145 for the scheduled message based on the number of TTIs 135 and / or the number of predetermined TTI instances 135. In one embodiment, there is a unique number of the number of TTIs 135 for the scheduled message for each number of signal reference positions 145 and / or predetermined TTI instances 135. The number of the number of TTIs 135 for the scheduled message may be determined from a lookup table.

[0074] In one embodiment, the processor 405 determines 510 the reference signal positions 145 by determining the number of reference signal positions 145 for the subframe 120 based on an operating criterion. For example, the operating criterion may specify that the reference signal 155 should be transmitted in three reference signal positions 145 at three predetermined TTI instances 135 for each subband 140.

[0075] In an alternative embodiment, processor 405 may determine the number of reference signal positions 145 for subframe 120 based on available bandwidth of network 115. For example, processor 405 may determine 505 that a greater number of reference signal positions 145 may be allocated for subframe 120 if the available bandwidth exceeds a bandwidth threshold.

[0076] Figure 5E Alternative embodiments are described for determining 510 the number of reference signal locations 145. The embodiments for determining the number of reference signal locations 145 may be used alone or in combination.

[0077] The processor may determine 510 the reference signal position 145 based on the number of predetermined TTI instances 135. For example, a lookup table may specify the reference signal position 145 for the predetermined TTI instance 135 such that the number of the predetermined TTI instance 135 is used as an index.

[0078] The processor 405 may determine the number of signal reference locations 145 and / or the number of predetermined TTI instances 135 for the scheduled transmission 135 based on the number of TTIs 135 in the plurality of TTIs 135. The processor 405 may determine the number of predetermined TTI instances 135 and / or the TTIs 135 of the predetermined TTI instances 135 for the scheduled transmission 165 based on the number of TTIs 135 in the plurality of TTIs 135.

[0079] In one embodiment, the processor 405 determines the signal reference position 145 and / or the number of predetermined TTI instances 135 for the scheduled transmission 165 based on the number of TTIs 135 in the plurality of TTIs 135, and one or more of a subframe index, a time interval between TTIs 135 in the scheduled transmission 165, a subframe size, and a TDD configuration for the scheduled transmission 165.

[0080] In one embodiment, the processor 405 may determine 510 the reference signal locations 145 based on one or more of the number of TTIs 135, the subframe index, the time interval between TTIs 135 in the scheduled transmission 165, the subband size, and the TDD configuration for the scheduled transmission 165. The one or more reference signal locations 145 may be in predetermined TTI instances 135 of the plurality of TTIs 135. The number of predetermined TTI instances 135 may be less than the number of the plurality of TTIs 135. The reference signal 155 may only be present in the predetermined TTI instances 135.

[0081] In one embodiment, the reference signal locations 145 are determined 510 to be in predetermined TTI instances 135 of the plurality of TTIs 135, and the number of predetermined TTI instances 135 is less than the number of the plurality of TTIs 135, wherein the reference signal 155 is present only in the predetermined TTI instances 135. In response to one TTI 135 in the scheduled transmission 165, one or more reference signal locations 145 may be determined 505 to be in a first predetermined TTI instance 135 at a first TTI 135a in the plurality of TTIs 135, such as Figure 3A In response to three consecutive TTIs 135 in the scheduled transmission 165, one or more reference signal locations 145 may be determined 505 as being in a first predetermined TTI instance 135 at a first TTI 135a and a third predetermined TTI instance 135 at a third TTI 135c in the plurality of TTIs 135, such as Figure 3B In response to seven consecutive TTIs 135 in the scheduled transmission 165, one or more reference signal locations 145 may be determined 505 as being at a first predetermined TTI instance 135 at a first TTI 135a, a third predetermined TTI instance 135 at a third TTI 135c, and a seventh predetermined TTI instance 135 at a seventh TTI 135g in the plurality of TTIs 135, such as Figure 3CAlternatively, in response to seven consecutive TTIs 135 in the scheduled transmission 165, at least one reference signal 155 may be determined 505 to be in a first predetermined TTI instance 135 at a first TTI 135a, a third predetermined TTI instance 135 at a third TTI 135c, and a sixth predetermined TTI instance 135 at a sixth TTI 135f in the plurality of TTIs 135.

[0082] In one embodiment, the one or more reference signal positions 145 are determined 510 to be in a predetermined subband instance 140 of a predetermined TTI instance 135. The one or more reference signal positions 145 of a second predetermined subband instance 140b of a second predetermined TTI instance 135 may be determined 505 based on the one or more reference signal positions of a first predetermined subband instance 140a of a first predetermined TTI instance 135, such as FIG. 3E to FIG. 3F shown.

[0083] In one embodiment, one or more reference signal positions 145 for the transmission layers of the scheduled transmissions 165 for the plurality of TTIs 135 are further determined 510 based on the parameters communicated in the resource assignment message 160. For example, the reference signal positions 145 may be calculated based on the parameters communicated in the resource assignment message 160. Additionally, the number of one or more reference signal positions 145 for the subbands 140 for the plurality of TTIs 135 may be further determined 505 from the resource assignment message 160. For example, the value in the resource assignment message 160 may specify the number of one or more reference signal positions 145 for the subbands 140.

[0084] In one embodiment, first and second pluralities of TTIs 135 having the same number of TTIs 135 and the same epoch may have different numbers of reference signal locations 145 based on the resource assignment message 165. For example, the first plurality of TTIs 135 may have a first number of reference signals 155 based on the first resource assignment message 165, and the second plurality of TTIs 135 may have a second number of reference signals 155 for the second plurality of TTIs 135 based on the second resource assignment message 165.

[0085] In a particular embodiment, a given reference signal 155 of the one or more reference signals 155 is mapped to two given reference signal locations 145 of two TTIs 135 of the plurality of TTIs 135 .

[0086] The one or more reference signal positions 145 may be determined 510 to be in the predetermined subband instance 140 of the predetermined TTI instance 135. The one or more reference signal positions 145 for the second predetermined subband instance 140b of the second predetermined TTI instance 135 may be determined based on the one or more reference signal positions 145 for the first predetermined subband instance 140a of the first predetermined TTI instance 135. For example, if the first predetermined TTI instance 135 of the first reference signal position 145 of the first predetermined subband instance 140 is at the third TTI 135c, then, based on the first predetermined TTI instance 135 being at the third TTI 135c, the second predetermined TTI instance 135 for the second reference signal position 145 in the second predetermined subband instance 140b may be in the second TTI 135b, such as Figure 3E shown.

[0087] In one embodiment, the number of first reference signals 155 for the first plurality of TTIs 135 is different from the number of second reference signals 155 for the second plurality of TTIs 135 that is the same as the first plurality of TTIs 135. The difference between the number of reference signals 155 for the first plurality of TTIs 135 and the number of reference signals for the second plurality of TTIs 135 may be communicated via the resource assignment message 160. For example, the first resource assignment message 160 for the first plurality of TTIs 135 may be used to determine the number of first reference signals 155 for the first plurality of TTIs 135, and the second resource assignment message 160 for the second plurality of TTIs 135 may be used to determine the number of second reference signals 155 for the second plurality of TTIs 135.

[0088] The processor 405 may schedule 515 the scheduled transmission 165 of the plurality of TTIs 135 to the user equipment 110. A predetermined TTI instance 135 in the plurality of TTIs 135 may include one or more reference signal positions 145 for the scheduled transmission 165. In one embodiment, a given reference signal 155 in the one or more reference signals 155 is mapped to two given reference signal positions 145 of two TTIs 135 in the plurality of TTIs 135. In one embodiment, the user equipment 110 may determine whether to map a given reference signal 155 in the one or more reference signals 155 to two given reference signal positions 145 of two TTIs 135 in the plurality of TTIs 135 based on the resource assignment message 165.

[0089] In one embodiment, a field in the DCI indicates the number of TTIs 135 and / or one or more reference signal positions 145. Additionally, a radio network temporary identifier (RNTI) may indicate the number of TTIs 135 and / or one or more reference signal positions 145. Alternatively, a fixed value of a field in a multi-TTI grant indicates the number of TTIs 135 and / or one or more reference signal positions 145. In a particular embodiment, a function of the time and / or frequency at which the multi-TTI grant is sent indicates the one or more reference signal positions 145 and / or the number of TTIs 135.

[0090] In one embodiment, a field in the DCI indicates whether the number of scheduled TTIs 135 is greater than 1. Additionally, the RNTI may indicate whether the number of scheduled TTIs 135 is greater than 1. Alternatively, a fixed value of a field in the multi-TTI grant indicates whether the number of scheduled TTIs 135 is greater than 1. In a particular embodiment, a function of the time and / or frequency at which the multi-TTI grant is sent indicates whether the number of scheduled TTIs 135 is greater than 1.

[0091] The processor 405 may send 520 a resource assignment message 160 to the user equipment 110 and the user equipment 110 may receive 555 the resource assignment message. The processor 405 of the user equipment 110 may determine 560 a number of the plurality of TTIs 135 in the scheduled transmission 165. The number of the plurality of TTIs 135 may be determined 560 from the resource assignment message 160.

[0092] In one embodiment, the processor 405 determines 565 a reference signal position 145 for the scheduled transmission 165 based on the number of the plurality of TTIs 135. The processor 405 of the user equipment 110 may determine the number of the plurality of TTIs 135 using a function and / or criterion used by the processor 405 of the base station 105 and / or a function and / or criterion that is inverse to the function and / or criterion used by the processor 405 of the base station 105.

[0093] In one embodiment, the reference signal location 145 is determined based solely on the number of TTIs 135. For example, the reference signal location 145 may be retrieved from a lookup table using the number of TTIs 135 as an index.

[0094] In a particular embodiment, the reference signal location 145 is determined 565 from one or more of the number of TTIs 135 and a resource assignment message 160, parameters received from a higher layer, a subframe index, a time interval between TTIs 135 in a scheduled transmission 165, a subband size, and a TDD configuration for the scheduled transmission 165, where the higher layer is higher than the physical layer.

[0095] In one embodiment, the reference signal locations 145 are determined 565 to be in predetermined TTI instances 135 of the plurality of TTIs 135, and the number of predetermined TTI instances 135 is less than the number of the plurality of TTIs 135, wherein the reference signal 155 is present only in the predetermined TTI instances 135. In response to one TTI 135 in the scheduled transmission 165, one or more reference signal locations 145 may be determined 565 to be in a first predetermined TTI instance 135 at a first TTI 135a in the plurality of TTIs 135, such as Figure 3A In response to three consecutive TTIs 135 in the scheduled transmission 165, one or more reference signal locations 145 may be determined 565 as being in a first predetermined TTI instance 135 at a first TTI 135a and a third predetermined TTI instance 135 at a third TTI 135c in the plurality of TTIs 135, such as Figure 3B In response to seven consecutive TTIs 135 in the scheduled transmission 165, one or more reference signal locations 145 may be determined 565 as being at a first predetermined TTI instance 135 at a first TTI 135a, a third predetermined TTI instance 135 at a third TTI 135c, and a seventh predetermined TTI instance 135 at a seventh TTI 135g in the plurality of TTIs 135, such as Figure 3C Alternatively, in response to seven consecutive TTIs 135 in the scheduled transmission 165, at least one reference signal 155 may be determined 565 to be in a first predetermined TTI instance 135 at a first TTI 135a, a third predetermined TTI instance 135 at a third TTI 135c, and a sixth predetermined TTI instance 135 at a sixth TTI 135f in the plurality of TTIs 135.

[0096] In one embodiment, the one or more reference signal locations 145 are determined 565 to be in a predetermined subband instance 140 of a predetermined TTI instance 135. The one or more reference signal locations 145 of a second predetermined subband instance 140b of a second predetermined TTI instance 135 may be determined 565 based on the one or more reference signal locations of a first predetermined subband instance 140a of a first predetermined TTI instance 135, such as FIG. 3E to FIG. 3F shown.

[0097] In one embodiment, one or more reference signal positions 145 for the transmission layers of the scheduled transmissions 165 for the plurality of TTIs 135 are further determined 565 based on the parameters received in the resource assignment message 160. For example, the reference signal positions 145 may be calculated based on the parameters received in the resource assignment message 160. Additionally, the number of one or more reference signal positions 145 for the subbands 140 for the plurality of TTIs 135 may be further determined 565 from the resource assignment message 160. For example, the value in the resource assignment message 160 may specify the number of one or more reference signal positions 145 for the subbands 140.

[0098] The one or more reference signal positions 145 are further determined 565 from a field in the DCI indicating the number of TTIs 135 and / or the one or more reference signal positions 145. Additionally, the number of TTIs 135 and / or the one or more reference signal positions 145 may be further determined from the RTNI. Alternatively, the number of TTIs 135 and / or the one or more reference signal positions 145 may be further determined 565 from a fixed value of a multi-TTI grant. In a particular embodiment, the number of TTIs 135 and / or the one or more reference signal positions 145 are further determined 565 based on the time and / or frequency at which the grant is sent.

[0099] In one embodiment, a field in the DCI indicates whether the number of scheduled TTIs 135 is greater than 1. Additionally, the RNTI may indicate whether the number of scheduled TTIs 135 is greater than 1. Alternatively, a fixed value of a field in the multi-TTI grant indicates whether the number of scheduled TTIs 135 is greater than 1. In a particular embodiment, a function of the time and / or frequency at which the multi-TTI grant is sent indicates whether the number of scheduled TTIs 135 is greater than 1.

[0100] In one embodiment, in response to different resource assignment messages 160 for first and second pluralities of TTIs 135 having the same number and duration of TTIs 135, the number of first reference signals 155 for the first plurality of TTIs 135 is different than the number of second reference signals 155 for the second plurality of TTIs 135. In a particular embodiment, a given reference signal 155 of the one or more reference signals 155 is mapped to two given reference signal locations 145 of two TTIs 135 of the plurality of TTIs 135.

[0101] Figure 5B and Figure 5C Additional embodiments are described for determining 565 reference signal location 145. The embodiments for determining 565 reference signal location 145 may be used alone or in any combination.

[0102] In one embodiment, the data may be precoded using a given precoding matrix for a first TTI 135 of a predetermined TTI instance 135 and a second TTI 135 that is not a predetermined TTI instance 135. The base station 105 may transmit 525 the data of the scheduled transmission 165 to the user equipment 110. The data may be transmitted over a plurality of TTIs 135. The reference signal 145 may be transmitted in one or more reference signal locations 145 at the predetermined TTI instance 135. The number of predetermined TTI instances 135 and / or corresponding reference signal locations 145 may be less than the number of TTIs 135 in the scheduled transmission 165. The user equipment 110 may receive 570 the data.

[0103] In one embodiment, the processor 405 demodulates 575 at least one TTI 135 in the scheduled transmission 165 using at least one reference signal 155 from one or more reference signal locations 145. The at least one TTI 135 may be demodulated 575 based on a previous reference signal 160 and at least one of a current reference signal 160 and a future reference signal 160, e.g., the TTI 135 may be demodulated 575 using scheduling information from each of a previous reference signal 164 of a previously scheduled transmission 165 and a current reference signal 164 of a currently scheduled transmission 165.

[0104] The user equipment 110 may transmit 580 an acknowledgement message 175 to the base station 105. In one embodiment, the user equipment 110 transmits 580 an acknowledgement message 175 corresponding to the demodulated data for each of the plurality of TTIs 135. The base station 105 may receive 530 the acknowledgement message 175, and the method 500 ends. The method 500 may be used for multi-TTI grant scheduling, and may be used to reduce reference signal delay.

[0105] Figure 5B 8 is a schematic flow chart illustrating one embodiment of a pattern assignment method 800. The method 800 may generate a pattern of reference signal positions 145 and assign the pattern to a subband 140. Figure 5A The method 800 may be used in steps 505 and 565 of the embodiment. The method 800 may be performed by the base station 105, the user equipment 110, or a combination thereof. In addition, the method 800 may be performed by the processor 405 of the base station 105 and / or the user equipment 110.

[0106] Method 800 and in one embodiment, processor 405 generates 805 a reference signal position pattern of reference signal positions 145. The reference signal position pattern may include a plurality of predetermined TTI instances 135. As used herein, "generate" refers to calculating, finding, and / or making a logical decision based on an input. The reference signal position pattern may be generated 805 based on the number of TTIs 135. Alternatively, the reference signal position pattern may be generated based on the number of reference signal positions, operating criteria, available bandwidth, and / or the possibility of interference. In one embodiment, the reference signal position pattern is generated 805 from one or more of the number of TTIs 135 and a resource assignment message 160, a parameter received from a higher layer, a subframe index, a time interval between TTIs 135 in a scheduled transmission 165, a subband size, and a TDD configuration for the scheduled transmission 165, wherein the higher layer is higher than the physical layer.

[0107] In the reference signal position pattern, the reference signal positions 145 may be present in some TTIs 135 of the slot 125 and / or the subframe 120 and absent in other TTIs 135 . FIG. 3E to FIG. 3F An example of a reference signal position pattern is illustrated. The processor 405 further assigns 810 the reference signal position pattern to the subbands 140. For example, the processor may assign 810 the first reference signal position pattern to the first subband 140a. The processor 405 further determines 815 whether the reference signal position pattern is assigned to all subbands 140. If the reference signal position pattern is not assigned to all subbands 140, the processor 405 may reorder 820 the reference signal position patterns. For example, Figure 3F The predetermined TTI instances 135 and / or reference signal positions 145 of the first subband 140a of the embodiment of the present invention may represent a first reference signal position pattern. The first reference signal position pattern may be reordered 820 to generate a pattern consisting of Figure 3F In another embodiment, the second reference signal position pattern represented by the predetermined TTI instance 135 and / or the reference signal position 145 of the second subband 140b can be determined based on one or more of the first reference signal position pattern and / or the resource assignment message 165. Figure 3F The predetermined TTI instances 135 and / or the reference signal positions 145 for the second subband 140b of the embodiment of the present invention represent a second reference signal position pattern.

[0108] The processor 405 continues to assign reference signal position patterns to the subbands 140 until the pattern has been assigned to all subbands 140 and the method 800 ends.

[0109] Figure 5C1 is a schematic flow chart illustrating one embodiment of a reference signal presence / absence determination method 600. The method 600 determines predetermined TTI instances 135 in which a reference signal 155 is present and TTIs 135 in which a reference signal 155 is not present. Figure 5A The method 600 may be used in steps 505 and 565 of the embodiment. The method 600 may be performed by the base station 105, the user equipment 110, or a combination thereof. In addition, the method 600 may be performed by the processor 405 of the base station 105 and / or the user equipment 110.

[0110] The method 600 begins, and in one embodiment, the processor 405 determines whether the distance between TTIs 135 in the scheduled transmission 165 is less than a distance threshold. The distance is the number of TTIs 135 between the last TTI 135 and the current TTI 135. If the number between TTIs 135 is not less than the distance threshold, then a predetermined TTI instance 135 for a reference signal position 145 and / or a reference signal 155 is determined 620 to be present in the current TTI 135. If the number between TTIs 135 is less than the distance threshold, then the processor 405 determines whether the current TTI 135 is an odd TTI 135, such as the first, third, fifth, and / or seventh TTI 135a / c / e / g. If the current TTI 135 is an odd TTI 135, then the reference signal position 145 and / or the reference signal 155 may be present 620 in the current TTI 135.

[0111] If the current TTI 135 is not an odd TTI 135, the predetermined TTI instance 135 for the reference signal position 145 and / or the reference signal 155 is determined not to exist at 615 the current TTI 135, and the method 600 ends. As a result, the reference signal position 145 can be determined based on the distance between TTIs 135 and the position of the TTI 135 within the time slot 125.

[0112] Figure 5D 6 is a schematic flow chart illustrating an embodiment of a reference signal port determination method 650. The method 650 determines an antenna port for transmitting a reference signal 155. The method 650 may be performed by a base station 105, a user equipment 110, or a combination thereof. In addition, the method 650 may be performed by a processor 405 of the base station 105 and / or the user equipment 110.

[0113] The method 650 starts and in one embodiment, the processor 405 determines 655 whether the scheduled transmission 165 supports up to epoch 8. The user equipment 110 may report the epoch to the base station 105. The base station 105 may decode the reported epoch to determine which antenna port to use to receive the transmission from the user equipment 110.

[0114] If up to TTI 8 is not supported, the method 650 ends. If up to TTI 8 is supported, the processor 405 determines 660 whether the reference signal 155 and / or the reference signal position 145 is in the current TTI 135. If the reference signal 155 and / or the reference signal position 145 is not in the current TTI 135, the method 650 ends.

[0115] If the reference signal 155 and / or the reference signal position 145 are in the current TTI 135, the processor 405 determines 670 whether the current TTI 135 is an odd TTI 135. An odd TTI 135 has an index number of 1, 3, 5, etc. If the current TTI 135 is not an odd TTI 135, the processor 405 may transmit 680 the reference signal 155 through one or more second antenna ports of the communication hardware 415, and the method 650 ends. If the current TTI 135 is an odd TTI 135, the processor 405 may transmit 675 the reference signal 155 through one or more first antenna ports of the communication hardware 415, and the method 650 ends.

[0116] Figure 5E 1 is a schematic flow chart illustrating an embodiment of a method for determining the number of reference signals. The method 700 may determine the number of reference signal locations 145 for a scheduled transmission 165. The method 700 may be Figure 5A Alternatively, method 700 may be Figure 5A The method 700 may be performed by the base station 105, the user equipment 110, or a combination thereof. In addition, the method 700 may be performed by the processor 405 of the base station 105 and / or the user equipment 110.

[0117] The method 700 begins, and in one embodiment, the processor 405 determines 705 whether the epoch is less than an epoch threshold. If the epoch is less than the epoch threshold, the processor 405 may decrease 710 the reference signal positions 145 for the scheduled transmission 165, and the method 700 ends. For example, the processor 405 may decrease 710 the reference signal positions 145 to 12 reference signal positions 145. If the epoch is not less than the epoch threshold, the processor 405 may increase 715 the reference signal positions 145 for the scheduled transmission 165, and the method 700 ends. For example, the processor 405 may increase 715 the reference signal positions 145 to 16 reference signal positions 145.

[0118] Embodiments described herein reduce the overhead of reference signals 155 by transmitting reference signals 155 in reference signal locations 145 at predetermined TTI instances 135 that are a subset of TTIs 135 of scheduled transmissions 165. Thus, the number of reference signals 155 is reduced, thereby reducing reference signal overhead.

[0119] Embodiments may be practiced in other specific forms. The described embodiments should be considered illustrative and not restrictive in all respects. Therefore, the scope of the present invention is indicated by the appended claims rather than by the foregoing description. All changes within the meaning and scope of the equivalents of the claims are encompassed within their scope.

Claims

1. A method performed by a user equipment UE, comprising: By using a processor, determining a set of periodic transmission time intervals (TTIs); receiving a resource assignment indication corresponding to the periodic TTI set, the resource assignment indication indicating a demodulation reference symbol (DMRS) pattern for the periodic TTI set; as well as Based on the indicated DMRS pattern, the time interval between two TTIs of the periodic TTI set, and the TTI index of the periodic TTI set, a DMRS symbol associated with the periodic TTI set is determined from a lookup table, wherein the periodic TTI set includes a first TTI subset and a second TTI subset, wherein the first TTI subset and the second TTI subset belong to a subframe, the first TTI and the third TTI of the first TTI subset contain DMRS symbols, and the second TTI and the fourth TTI of the second TTI subset do not contain DMRS symbols.

2. The method according to claim 1, wherein: The TTIs of the periodic TTI set are continuous.

3. The method according to claim 1, wherein: The number of DMRS symbols associated with the periodic TTI set is less than the number of TTIs of the periodic TTI set.

4. The method according to claim 1, wherein: The number of TTIs having DMRS symbols is less than the number of TTIs of the periodic TTI set.

5. The method according to claim 1, wherein: The last TTI of the subframe contains DMRS symbols.

6. The method according to claim 1, wherein: The second TTI, the third TTI, the fourth TTI and the fifth TTI of the subframe have a duration of two symbols.

7. The method according to claim 1, wherein: The fifth TTI of the subframe includes a DMRS symbol.

8. The method according to claim 1, wherein: The resource assignment indication is an uplink grant.

9. The method according to claim 1, wherein: Data transmissions in at least one TTI in the subframe are demodulated using at least one of the DMRS symbols associated with the subframe.

10. The method according to claim 9, wherein: Data transmission in at least one TTI of the subframe is demodulated based on the DMRS symbols in a next TTI of the subframe.

11. The method of claim 10, the confirmation message being associated with data demodulated for each TTI in the set of periodic TTIs.

12. The method according to claim 1, wherein: The resource assignment indication includes at least one of the following: a parameter received from a higher layer, a subframe index, a time interval between two TTIs of scheduled transmission, a subband size, and a time division duplex (TDD) configuration for the scheduled transmission, wherein the higher layer is higher than the physical layer.

13. A user equipment UE, comprising: A processor, the processor executing: determining a set of periodic transmission time intervals (TTIs); receiving a resource assignment indication corresponding to the periodic TTI set, the resource assignment indication indicating a demodulation reference symbol (DMRS) pattern for the periodic TTI set; as well as Based on the indicated DMRS pattern, the time interval between two TTIs of the periodic TTI set, and the TTI index of the periodic TTI set, a DMRS symbol associated with the periodic TTI set is determined from a lookup table, wherein the periodic TTI set includes a first TTI subset and a second TTI subset, wherein the first TTI subset and the second TTI subset belong to a subframe, the first TTI and the third TTI of the first TTI subset contain DMRS symbols, and the second TTI and the fourth TTI of the second TTI subset do not contain DMRS symbols.

14. The UE according to claim 13, wherein: The TTIs of the periodic TTI set are continuous.

15. The UE according to claim 13, wherein: The number of DMRS symbols associated with the periodic TTI set is less than the number of TTIs of the periodic TTI set.

16. The UE according to claim 13, wherein: The number of TTIs having DMRS symbols is less than the number of TTIs of the periodic TTI set.

17. The UE according to claim 13, wherein: The last TTI of the subframe contains DMRS symbols.

18. A program product comprising a non-transitory computer-readable storage medium and storing code, the code being executable by a processor to perform: determining a set of periodic transmission time intervals (TTIs); receiving a resource assignment indication corresponding to the periodic TTI set, the resource assignment indication indicating a demodulation reference symbol (DMRS) pattern for the periodic TTI set; and Based on the indicated DMRS pattern, the time interval between two TTIs of the periodic TTI set, and the TTI index of the periodic TTI set, a DMRS symbol associated with the periodic TTI set is determined from a lookup table, wherein: The periodic TTI set includes a first TTI subset and a second TTI subset, wherein the first TTI subset and the second TTI subset belong to a subframe, the first TTI and the third TTI of the first TTI subset contain DMRS symbols, and the second TTI and the fourth TTI of the second TTI subset do not contain DMRS symbols.

19. The program product according to claim 18, wherein: The TTIs of the periodic TTI set are continuous.

20. The program product according to claim 18, wherein: The number of DMRS symbols associated with the periodic TTI set is less than the number of TTIs of the periodic TTI set.

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