WO2010049584A1

WO2010049584A1 - Backwards compatible downlink assignment index

Info

Publication number: WO2010049584A1
Application number: PCT/FI2009/050847
Authority: WO
Inventors: Peng Chen; Chunyan Gao; Xiangguang Che
Original assignee: Nokia Corporation
Priority date: 2008-10-29
Filing date: 2009-10-21
Publication date: 2010-05-06

Abstract

In certain exemplary embodiments, methods, apparatus and computer programs are disclosed that include indicating in a downlink assignment index field in an uplink grant for a user equipment a total number of downlink grants within a downlink grant region comprising a portion of a resource space, wherein the resource space comprises a plurality of subframes, each subframe having a plurality of chunks. These further include indicating in a downlink assignment index field of a downlink grant for a user equipment a number of downlink grants in a selected region of the resource space.

Description

BACKWARDS COMPATIBLE DOWNLINK ASSIGNMENT INDEX

TECHNICAL FIELD:

The exemplary and non- limiting embodiments of this invention relate generally to wireless communication systems, methods, devices and computer programs and, more specifically, relate to extended bandwidth wireless systems and the signaling of ACK/NACK indications between a user device and a network access node.

BACKGROUND:

This section is intended to provide a background or context to the invention that is recited in the claims. The description herein may include concepts that could be pursued, but are not necessarily ones that have been previously conceived or pursued. Therefore, unless otherwise indicated herein, what is described in this section is not prior art to the description and claims in this application and is not admitted to be prior art by inclusion in this section.

The following abbreviations that may be found in the specification and/or the drawing figures are defined as follows:

3GPP third generation partnership project

ACK acknowledge

BW bandwidth DAI downlink assignment index

DL downlink (eNB towards UE)

DTX discontinuous transmission eNB EUTRAN Node B (evolved Node B)

EPC evolved packet core EUTRAN evolved UTRAN (LTE)

FDD frequency division duplex

FDMA frequency division multiple access HARQ hybrid automatic repeat request

HO handover

LTE long term evolution

MAC medium access control

MM/MME mobility management/mobility management entity

NACK not acknowledge/negative acknowledge

Node B base station

OFDMA orthogonal frequency division multiple access

O&M operations and maintenance PDCCH physical downlink control channel

PDCP packet data convergence protocol

PDSCH physical downlink shared channel

PHY physical (layer 1)

PUCCH physical uplink control channel PUSCH physical uplink shared channel

RLC radio link control

RRC radio resource control

RRM radio resource management

SGW serving gateway SCFDMA single carrier, frequency division multiple access

TDD time division duplex

UE user equipment

UL uplink (UE towards eNB)

UTRAN universal terrestrial radio access network

A communication system known as evolved UTRAN (EUTRAN, also referred to as UTRANLTE or as EUTRA) is nearing completion of development within the 3GPP. As presently specified the DL access technique will be OFDMA, and the UL access technique will be SCFDMA.

One specification of interest is 3GPP TS 36.300, V8.5.0 (2008-05), 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (EUTRA) and Evolved Universal Terrestrial Access Network (EUTRAN); Overall description; Stage 2 (Release 8).

Figure 1 reproduces Figure 4.1 of 3GPP TS 36.300, and shows the overall architecture of the EUTRAN system. The EUTRAN system includes eNBs, providing the EUTRA user plane (PDCP/RLC/MAC/PHY) and control plane (RRC) protocol terminations towards the UE. The eNBs are interconnected with each other by means of an X2 interface. The eNBs are also connected by means of an Sl interface to an EPC, more specifically to a

MME (Mobility Management Entity) by means of a Sl MME interface and to a Serving Gateway (SGW) by means of a S 1 interface. The S 1 interface supports a many to many relationship between MMEs / Serving Gateways and eNBs.

The eNB hosts the following functions: functions for Radio Resource Management: Radio Bearer Control, Radio Admission Control, Connection Mobility Control, Dynamic allocation of resources to UEs in both uplink and downlink (scheduling);

IP header compression and encryption of the user data stream; selection of a MME at UE attachment; routing of User Plane data towards Serving Gateway; scheduling and transmission of paging messages (originated from the MME); scheduling and transmission of broadcast information (originated from the MME or

O&M); and a measurement and measurement reporting configuration for mobility and scheduling.

Also of interest herein are further releases of 3GPP LTE targeted towards future wireless communication systems, which may be referred to herein for convenience simply as LTE- Advanced (LTE-A), or as ReI. 9, or as ReI. 10. For example, reference can be made to 3GPP TR 36.913, V8.0.0 (2008-06), 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Requirements for Further Advancements for E-UTRA (LTE -Advanced) (Release X). LTE-A is intended to be an evolution of the LTE ReI. 8 system that fulfills the ITU-R requirements for IMT -Advanced. One of the main assumptions for LTE-A made by 3GPP is related to backwards compatibility. That is, a ReI. 8 E-UTRA terminal must be able to operate in an Advanced E-UTRAN system, and an advanced E-UTRA terminal should be operable in a ReI. 8 E-UTRAN system.

In order to address the backwards compatibility requirements carrier aggregation is being considered as a method to extend the BW in the LTE-A system. Channel aggregation can be viewed as a multi-carrier extension of LTE ReI. 8. From an UL/DL control signaling point of view, a most straightforward multi-carrier concept is simply copy the existing ReI.

8 control plane (PDCCH, PUCCH, etc) to each chunk (i.e., frequency portion or BW portion of the spectrum). One may refer to this concept as a NxPDCCH structure in LTE-A

It can be shown that for UEs having resource allocations in multiple chunks, the use of a per chunk HARQ mechanism is an efficient approach. In LTE ReI.8 TDD, a 2-bit DAI field is added to DCI formats 1, IA, IB, 2 to handle the error cases due to DL grants missing. In addition, a DAI containing the number of allocated subframes within a "scheduling window" is also suggested to be added in the UL grant to handle error cases if ACK/NACK(s) are to be transmitted on the PUSCH.

Reference with regard to ReI. 8 TDD use of the DAI may be made to 3GPP TS 36.213 V8.4.0 (2008-09) Technical Specification 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA); Physical layer procedures (Release 8), for example clause 7.3 entitled "UE procedure for reporting ACK/NACK". 3GPP TS 36.213 V8.4.0.

SUMMARY

In one aspect, an apparatus is disclosed that includes 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: (1) indicating in a downlink assignment index field in an uplink grant for a user equipment a total number of downlink grants within a downlink grant region comprising a portion of a resource space, wherein the resource space comprises a plurality of subframes, each sub frame having a plurality of chunks; and (2) indicating in a downlink assignment index field of a downlink grant for a user equipment a number of downlink grants in a selected region of the resource space.

In another aspect, a method is disclosed that includes indicating in a downlink assignment index field in an uplink grant for a user equipment a total number of downlink grants within a downlink grant region comprising a portion of a resource space, wherein the resource space comprises a plurality of subframes, each subframe having a plurality of chunks. The method further includes indicating in a downlink assignment index field of a downlink grant for a user equipment a number of downlink grants in a selected region of the resource space.

In a third aspect, a computer program is disclosed that comprises code for indicating in a downlink assignment index field in an uplink grant for a user equipment a total number of downlink grants within a downlink grant region comprising a portion of a resource space, wherein the resource space comprises a plurality of subframes, each subframe having a plurality of chunks. The computer program further comprises code for indicating in a downlink assignment index field of a downlink grant for a user equipment a number of downlink grants in a selected region of the resource space. The code performs functions when the computer program is run on a processor.

BRIEF DESCRIPTION OF THE DRAWINGS

In the attached Drawing Figures:

Figure 1 reproduces Figure 4 of 3GPP TS 36.300, and shows the overall architecture of the EUTRAN system.

Figure 2A shows a simplified block diagram of various electronic devices that are suitable for use in practicing the exemplary embodiments of this invention.

Figure 2B shows a more particularized block diagram of a user equipment such as that shown at Figure 2A.

Figure 3 depicts a first embodiment of a DAI design, wherein DAI in an UL grant indicates the total number of DL grants within its "DL grant region", and DAI in a DL grant indicates the previous number of DL grants within a current subframe over the entire UE reception bandwidth.

Figure 4 depicts another embodiment of a DAI design, wherein DAI in an UL grant indicates the total number of DL grants within its "DL grant region", and DAI in a DL grant indicates the previous number of DL grants within a current chunk over an entire scheduling window.

Figure 5 depicts another embodiment of a DAI design, wherein DAI in an UL grant indicates the total number of DL grants within its "DL grant region", and DAI in a DL grant indicates the previous number of DL grants within a current "DL grant region".

Figure 6 is a logic flow diagram that illustrates the operation of a method, and a result of execution of computer program instructions embodied on a computer readable memory, in accordance with a first exemplary embodiment of this invention.

Figure 7 is a logic flow diagram that illustrates the operation of a method, and a result of execution of computer program instructions embodied on a computer readable memory, in accordance with a second exemplary embodiment of this invention.

Figure 8 is a logic flow diagram that illustrates the operation of a method, and a result of execution of computer program instructions embodied on a computer readable memory, in accordance with a third exemplary embodiment of this invention.

DETAILED DESCRIPTION

The exemplary embodiments of this invention relate at least in part to the LTE-A system of 3GPP, and pertain most particularly to the TDD mode. These exemplary embodiments consider the DAI design for ACK/NACK transmission on the PUSCH in the LTE-A TDD mode of operation having the NxPDCCH structure.

With respect to the DAI design in LTE-A TDD, the inventors make the following observations.

As in the LTE Rel.8 TDD, both ACK/NACK bundling (to improve UL coverage) and ACK/NACK multiplexing (to improve system throughput) should be supported in LTE-A TDD. Further, in order to provide backwards compatibility with Rel.8 a 2-bit DAI in the DL grant and a 2-bit DAI in UL grant should be kept in LTE-A TDD. However, if ACK/NACKs are to be transmitted on the PUSCH in LTE-A TDD with the NxPDCCH structure, certain problems can arise due to certain specific features of LTE-A.

In the ACK/NACK bundling mode both the UE and eNB need to know how many packets have been transmitted in the DL, and that thus need to be simultaneously

ACK/NACKed. In the Rel.8 TDD mode the DAI bits in the DL grant and in the UL grant are used to jointly indicate this. However, in LTE-A TDD multiple chunks may be allocated to one subframe. This implies that more assignments within one "scheduling window" need to be indicated through the DAI in the DL and UL grants if the NxPDCCH structure is adopted. Otherwise, a DTX to ACK error can occur.

Further, in the ACK/NACK multiplexing mode at least two options may be used to determine the number of ACK/NACK feedbacks. A first option is that the number of ACK/NACK feedbacks is determined by the possible maximum number of assignments within the "scheduling window" (i.e. configuration-specific feedback). A second option is that the number of ACK/NACK feedbacks is determined by the "actual" number of assignments within the "scheduling window" (i.e., assignment-specific feedback). It should be noted that, in LTE-A TDD, 'configuration-specific feedback' implies that the UE always must reserve a possible maximum number of ACK/NACK resources to support ACK/NACK multiplexing. Considering the fact that multiple chunks may be allocated within one subframe, this method is inefficient and less attractive in LTE-A TDD as it implies possibly unacceptable UL resource consumption/reservation. However, to support 'assignment-specific feedback' in LTE-A TDD, the assignments within one "scheduling window" are needed to be indicated exactly through DAI in the DL and UL grants. Otherwise a misunderstanding concerning multiple ACK/NACK feedbacks may occur between the UE and the eNB, which may lead to severe error cases.

Furthermore, from a backwards compatibility with ReI.8 point of view, using only the existing DAI bits (in the DL grant and the UL grant) to handle these various cases would be the most desirable procedure.

In view of the foregoing observations it should be appreciated that in the DAI design (in the DL/UL grants) for ACK/NACK transmission on the PUSCH in the LTE-A TDD with the NxPDCCH structure, it is necessary to consider certain specific features of the LTE-A TDD, as well as to consider backwards compatibility with the ReI.8 TDD.

Before describing in further detail the exemplary embodiments of this invention, reference is made to Figure 2A for illustrating a simplified block diagram of various electronic devices and apparatus that are suitable for use in practicing the exemplary embodiments of this invention. In Figure 2A a wireless network 1 is adapted for communication over a wireless link 11 with an apparatus, such as a mobile communication device which may be referred to as a UE 10, via a network access node, such as a Node B (base station), and more specifically an eNB 12. The network 1 may include a network control element (NCE) 14 that may include the MME/SGW functionality shown in Figure 1, and which provides connectivity with a network 1, such as a telephone network and/or a data communications network (e.g., the internet). The UE 10 includes a controller, such as a computer or a data processor (DP) 1 OA, a computer-readable memory medium embodied as a memory (MEM) 1OB that stores a program of computer instructions (PROG) 1OC, and a suitable radio frequency (RF) transceiver 1OD for bidirectional wireless communications with the eNB 12 via one or more antennas. The eNB 12 also includes a controller, such as a computer or a data processor (DP) 12 A, a computer-readable memory medium embodied as a memory (MEM) 12B that stores a program of computer instructions (PROG) 12C, and a suitable RF transceiver 12D for communication with the UE 10 via one or more antennas. The eNB 12 is coupled via a data / control path 13 to the NCE 14. The path 13 may be implemented as the Sl interface shown in Figure 1. The eNB 12 may also be coupled to another eNB via data / control path 15, which may be implemented as the X2 interface shown in Figure 1.

At least one of the PROGs 1 OC and 12C is assumed to include program instructions that, when executed by the associated DP, enable the device to operate in accordance with the exemplary embodiments of this invention, as will be discussed below in greater detail.

That is, the exemplary embodiments of this invention may be implemented at least in part by computer software executable by the DP 1OA of the UE 10 and/or by the DP 12A of the eNB 12, or by hardware, or by a combination of software and hardware (and firmware).

For the purposes of describing the exemplary embodiments of this invention the UE 10 may be assumed to also include a physical (PHY) layer unit 1OE, and the eNB 12 may include a corresponding PHY layer unit 12E, that are assumed to operate with the DAI design for ACK/NACK transmission on the PUSCH in the LTE-A TDD mode of operation having the NxPDCCH structure, as described in detail below.

Note that in a typical use case scenario there will be a plurality of UEs 10 present. Some of the UEs may be LTE-A compatible, while others may be ReI. 8 compatible. As such, backwards compatibility with the ReI. 8 UEs is an important consideration when specifying the operational characteristics of the LTE-A UEs.

In general, the various embodiments of the UE 10 can include, but are not limited to, cellular telephones, personal digital assistants (PDAs) having wireless communication capabilities, portable computers having wireless communication capabilities, image capture devices such as digital cameras having wireless communication capabilities, gaming devices having wireless communication capabilities, music storage and playback appliances having wireless communication capabilities, Internet appliances permitting wireless Internet access and browsing, as well as portable units or terminals that incorporate combinations of such functions. The computer readable MEMs 1OB and 12B may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor based memory devices, flash memory, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory. The DPs 1OA and 12A may be of any type suitable to the local technical environment, and may include one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on multi-core processor architecture, as non-limiting examples.

Figure 2B illustrates further detail of an exemplary UE 10 in both plan view (left) and sectional view (right), and the invention may be embodied in one or some combination of those more function-specific components. At Figure 2B the UE 10 has a graphical display interface 20 and a user interface 22 illustrated as a keypad but understood as also encompassing touch screen technology at the graphical display interface 20 and voice recognition technology received at the microphone 24. A power actuator 26 controls the device being turned on and off by the user. The exemplary UE 10 may have a camera 28 which is shown as being forward facing (e.g., for video calls) but may alternatively or additionally be rearward facing (e.g., for capturing images and video for local storage). The camera 28 is controlled by a shutter actuator 30 and optionally by a zoom actuator 30 which may alternatively function as a volume adjustment for the speaker(s) 34 when the camera 28 is not in an active mode.

Within the sectional view of Fig. 2B are seen multiple transmit/receive antennas 36 that are typically used for cellular communication. The antennas 36 may be multi-band for use with other radios in the UE. The operable ground plane for the antennas 36 is shown by shading as spanning the entire space enclosed by the UE housing though in some embodiments the ground plane may be limited to a smaller area, such as disposed on a printed wiring board on which the power chip 38 is formed. The power chip 38 controls power amplification on the channels being transmitted and/or across the antennas that transmit simultaneously where spatial diversity is used, and amplifies the received signals.

The power chip 38 outputs the amplified received signal to the radio-frequency (RF) chip 40 which demodulates and downconverts the signal for baseband processing. The baseband (BB) chip 42 detects the signal which is then converted to a bit stream and finally decoded. Similar processing occurs in reverse for signals generated in the apparatus 10 and transmitted from it.

Signals going to and from the camera 28 pass through an image/video processor 44 that operates to encode and decode the various image frames. A separate audio processor 46 may also be present controlling signals to and from the speakers 34 and the microphone 24. The graphical display interface 20 is refreshed from a frame memory 48 as controlled by a user interface chip 50 which may process signals to and from the display interface 20 and/or additionally process user inputs from the keypad 22 and elsewhere.

Certain embodiments of the UE 10 may also include one or more secondary radios such as a wireless local area network radio WLAN 37 and a Bluetooth7 radio 39, which may incorporate an antenna on-chip or be coupled to an off-chip antenna. Throughout the apparatus are various memories such as random access memory RAM 43, read only memory ROM 45, and in some embodiments a removable memory such as the illustrated memory card 47 on which the various programs 1OC are stored. All of these components within the UE 10 are normally powered by a portable power supply such as a battery 49.

The aforesaid processors 38, 40, 42, 44, 46, 50, if embodied as separate entities in a UE 10 or eNB 12, may operate in a slave relationship to the main processor 1OA, 12A, which may then be in a master relationship to them. In some embodiments the functionality may be disposed across various chips and memories as shown or disposed within another processor that combines some of the functions described above for Figure 2B. Any or all of these various processors of Fig. 2B access one or more of the various memories, which may be on-chip with the processor or separate from the processor. Similar function- specific components that are directed toward communications over a network broader than a piconet (e.g., components 36, 38, 40, 42-45 and 47) may also be disposed in exemplary embodiments of the access node 12, which may have an array of tower- mounted antennas rather than the two shown at Fig. 2B. Note that the various chips (e.g., 38, 40, 42, etc.) that were described above may be combined into a fewer number than described and, in a most compact case, may all be embodied physically within a single chip.

Described now are various exemplary and non- limiting embodiments for a DAI design for ACK/NACK transmission on the PUSCH in the LTE-A TDD with the NxPDCCH structure.

One may first consider a high level rule:

in LTE-A TDD with the NxPDCCH structure, it is desirable to re-use the 2-bit DAI in the

DL grant and the 2-bit DAI in the UL grant in order to handle error cases for both the

ACK/NACK bundling and the ACK/NACK multiplexing modes, in the case that the

ACK/NACK(s) is transmitted on the PUSCH.

One advantage that is realized by conforming to this rule is that it is fully compatible with

ReI.8, and no additional signaling overhead is introduced.

In addition, for all UL grants there is performed a one-to-one or a many-to-one mapping between the chunk(s) (within the entire bandwidth or the UE reception bandwidth) and the UL grant. The mapping may be a pre-defined mapping, or it may be a dynamic mapping, and the mapping (or mapping rule) is known by both the UE 10 and the eNB 12.

Furthermore, for each particular UL grant the DL grants within its associated chunk(s) over the entire "scheduling window" form a "DL grant region" for the particular UL grant.

In addition, the 2-bit DAI in the UL grant indicates the total number of DL grants within its "DL grant region".

In addition, the 2-bit DAI in the DL grant indicates, in a first embodiment, the previous/or total number of DL grants within the current subframe over the entire bandwidth or UE reception bandwidth, or in a second embodiment the previous/or total number of DL grants within the current chunk over entire "scheduling window", or in athird embodiment the previous/or total number of DL grants within the current "DL grant region".

In order to maintain the number of DAI bits at 2, a 'wrap-around' method (i.e., mod (4)) may be used in the DAI encoding. The implementation of the 'wrap-around' method is straightforward and may be viewed as a simple extension from the DAI definition. For example, if one uses m to indicate the previous/or total number of DL grants within the certain region, from the eNB 12 perspective the DAI is set according to (m) mod 4. From the UE 10 perspective, the UE 10 compares the value of the DAI with {the previous/or total number of received/detected DL grants within the certain region) mod 4. Thus, the error cases due to DL grant(s) missing are detectable by the UE 10.

In LTE-A TDD with the NxPDCCH structure, one may assume as an example that four DL subframes are associated with one UL subframe, and the UE 10 reception bandwidth is set as five chunks. In accordance with this non-limiting example, Figures 3-5 depict various DAI design examples.

Figure 3 depicts a first embodiment of the DAI design and method, wherein the DAI in an UL grant indicates the total number of DL grants within its "DL grant region", and the DAI in a DL grant indicates the previous number of DL grants within a current subframe over the entire UE reception bandwidth. Figure 4 depicts another embodiment of the DAI design and method, wherein the DAI in an UL grant indicates the total number of DL grants within its "DL grant region", and the DAI in a DL grant indicates the previous number of DL grants within a current chunk over an entire scheduling window. Note that DL grant region #1 includes two chucks. Figure 5 depicts another embodiment of the DAI design and method, wherein the DAI in the UL grant indicates the total number of DL grants within its "DL grant region", and the DAI in the DL grant indicates the previous number of DL grants within a current "DL grant region".

If one assumes the use of the 2-bit DAI in the DL grant, and a "pure counter" approach, then in accordance with a first method the 2-bit DAI in the DL grant indicates the previous number of DL grants within the current subframe over the entire UE reception bandwidth; in accordance with a second method the 2-bit DAI in the DL grant indicates the previous number of DL grants within the current chunk over the entire "scheduling window"; and in accordance with third method the 2-bit DAI in the DL grant indicates the previous number of DL grants within current "DL grant region".

As can be appreciated, these various exemplary approaches to providing DAI bits in the DL grant and the UL grant are suitable for use with LTE-A TDD with the NxPDCCH structure, and furthermore a fully compatible with ReI.8 TDD and do not require additional signaling overhead as compared with the approach taken in ReI. 8 TDD.

Based on the foregoing it should be apparent that the exemplary embodiments of this invention provide a method, apparatus and computer program(s) to provide backwards compatible signaling in the LTE-A system.

Figure 6 is a logic flow diagram that illustrates the operation of a method, and a result of execution of computer program instructions, in accordance with the exemplary embodiments of this invention.

In accordance with these exemplary embodiments a method performs, at Block 6A, a step of indicating using a DAI field in an UL grant a total number of DL grants within a DL grant region, and at Block 6B indicating in a DAI field in a DL grant a previous or total number of DL grants within a current subframe over an entire UE reception bandwidth.

Figure 7 is a logic flow diagram that illustrates the operation of a method, and a result of execution of computer program instructions, in accordance with the exemplary embodiments of this invention.

In accordance with these exemplary embodiments a method performs, at Block 7A, a step of indicating using a DAI field in an UL grant a total number of DL grants within a DL grant region, and at Block 7B indicating in a DAI field in a DL grant a previous or total number of DL grants within a current chunk over an entire scheduling window. Figure 8 is a logic flow diagram that illustrates the operation of a method, and a result of execution of computer program instructions, in accordance with the exemplary embodiments of this invention.

In accordance with these exemplary embodiments a method performs, at Block 8 A, a step of indicating using a DAI field in an UL grant a previous or total number of DL grants within a DL grant region, and at Block 8B indicating in a DAI field in a DL grant a total number of DL grants within a current DL grant region.

In each of these methods the DAI field may be two bits for each of the UL grant and the DL grant as taken in ReI. 8 TDD.

In each of these methods, for the UL grants there may be performed a one-to-one or a many-to-one mapping between the chunk(s), within the entire bandwidth or the UE reception bandwidth, where the mapping may be one of pre-defined or dynamic using a mapping rule known to both the UE and to the eNB, and where for each particular UL grant those DL grants within its associated chunk(s) over the entire scheduling window form the DL grant region for the particular UL grant.

Each of these methods may comprise the use of a wrap-around (mod (4)) method to encode the DAI, where m indicates a previous/or total number of DL grants within a certain region, and where the DAI is set according to (m) mod (4).

In the method of the preceding paragraph, further comprising comparing the value of the DAI with {the previous/ or total number of received/ detected DL grants within the certain region) mod (4) for enabling a user equipment to detect a case of a missing DL grant.

The various blocks shown in Figures 6, 7 and 8 may be viewed as method steps, and/or as operations that result from operation of computer program code, and/or as a plurality of coupled logic circuit elements constructed to carry out the associated function(s). In general, Figures 6, 7 and 8 may be viewed as being descriptive of the operations of the PHY layer units 1OE and 12E of Figure 2A. The various exemplary embodiments may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. For example, some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device, although the invention is not limited thereto. While various aspects of the exemplary embodiments of this invention may be illustrated and described as block diagrams, flow charts, or using some other pictorial representation, it is well understood that these blocks, apparatus, systems, techniques or methods described herein may be implemented in, as non- limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

It should thus be appreciated that at least some aspects of the exemplary embodiments of the inventions may be practiced in various components such as integrated circuit chips and modules, and that the exemplary embodiments of this invention may be realized in an apparatus that is embodied as an integrated circuit. The integrated circuit, or circuits, may comprise circuitry (as well as possibly firmware) for embodying at least one or more of a data processor or data processors, a digital signal processor or processors, baseband circuitry and radio frequency circuitry that are configurable so as to operate in accordance with the exemplary embodiments of this invention.

Various modifications and adaptations to the foregoing exemplary embodiments of this invention may become apparent to those skilled in the relevant arts in view of the foregoing description, when read in conjunction with the accompanying drawings. However, any and all modifications will still fall within the scope of the non- limiting and exemplary embodiments of this invention.

For example, while the exemplary embodiments have been described above in the context of the EUTRAN (UTRAN-LTE) system and the LTE-A system, it should be appreciated that the exemplary embodiments of this invention are not limited for use with only this one particular type of wireless communication system, and that they may be used to advantage in other wireless communication systems.

It should be noted that the terms "connected," "coupled," or any variant thereof, mean any connection or coupling, either direct or indirect, between two or more elements, and may encompass the presence of one or more intermediate elements between two elements that are "connected" or "coupled" together. The coupling or connection between the elements can be physical, logical, or a combination thereof. As employed herein two elements may be considered to be "connected" or "coupled" together by the use of one or more wires, cables and/or printed electrical connections, as well as by the use of electromagnetic energy, such as electromagnetic energy having wavelengths in the radio frequency region, the microwave region and the optical (both visible and invisible) region, as several non- limiting and non-exhaustive examples.

Further, the various names used for the described parameters (e.g., ACK/NACK, DAI, etc.) are not intended to be limiting in any respect, as these parameters may be identified by any suitable names. Further, the various names assigned to different channels (e.g., PDSCH, PUSCH, PDCCH, etc.) are not intended to be limiting in any respect, as these various channels may be identified by any suitable names.

Furthermore, some of the features of the various non-limiting and exemplary embodiments of this invention may be used to advantage without the corresponding use of other features. As such, the foregoing description should be considered as merely illustrative of the principles, teachings and exemplary embodiments of this invention, and not in limitation thereof.

Claims

CLAIMSWhat is claimed is:

1. 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 configured to, with the at least one processor, cause the apparatus to perform at least the following: indicating in a downlink assignment index field in an uplink grant for a user equipment a total number of downlink grants within a downlink grant region comprising a portion of a resource space, wherein the resource space comprises a plurality of subframes, each subframe having a plurality of chunks; and indicating in a downlink assignment index field of a downlink grant for a user equipment a number of downlink grants in a selected region of the resource space.

2. The apparatus of claim 1 , wherein indicating in a downlink assignment index field of a downlink grant further comprises indicating in the downlink assignment index field one of a previous or a total number of downlink grants within a current subframe over an entire bandwidth that includes all of the chunks for the current subframe.

3. The apparatus of claim 1 , wherein indicating in a downlink assignment index field of a downlink grant further comprises indicating in the downlink assignment index field one of a previous or a total number of downlink grants within a current one of the plurality of chunks over an entire scheduling window that includes one or more selected chunks for each of the plurality of subframes.

4. The apparatus of claim 1 , wherein indicating in a downlink assignment index field of a downlink grant further comprises indicating in the downlink assignment index field one of a previous or a total number of downlink grants within a current downlink grant region.

5. The apparatus of any one of claims 1 to 4, where the downlink grant region for each particular uplink grant comprises downlink grants within chunks associated with an entire scheduling window.

6. The apparatus of any one of claims 1 to 5, where for the uplink grants, there is a one-to-one or a many-to-one mapping between the chunks, within an entire bandwidth of the resource space or an entire bandwidth of the plurality of chunks for a subframe, where the mapping may be one of pre-defined or dynamic using a mapping rule known to both a user equipment and to a base station.

7. The apparatus of any one of claims 1 to 6, wherein the at least one memory and the computer program code are further configured to, with the at least one processor, cause the apparatus to encode each downlink assignment index using (m) mod (4), where m indicates a previous or total number of downlink grants within the selected region.

8. The apparatus of claim 7, wherein the at least one memory and the computer program code are further configured to, with the at least one processor, cause the apparatus to compare the value of a selected one of the downlink assignment indexes with (the previous or total number of received or detected downlink grants within the selected region) mod (4) to enable a user equipment to detect a case of a missing downlink grant.

9. The apparatus of any one of the preceding claims, wherein the downlink assignment index field comprises two bits for each of the uplink grant and the downlink grant.

10. A method, comprising: indicating in a downlink assignment index field in an uplink grant for a user equipment a total number of downlink grants within a downlink grant region comprising a portion of a resource space, wherein the resource space comprises a plurality of subframes, each sub frame having a plurality of chunks; and indicating in a downlink assignment index field of a downlink grant for a user equipment a number of downlink grants in a selected region of the resource space.

11. The method of claim 10, wherein indicating in a downlink assignment index field of a downlink grant further comprises indicating in the downlink assignment index field one of a previous or a total number of downlink grants within a current subframe over an entire bandwidth that includes all of the chunks for the current subframe.

12. The method of claim 10, wherein indicating in a downlink assignment index field of a downlink grant further comprises indicating in the downlink assignment index field one of a previous or a total number of downlink grants within a current one of the at least one chunks over an entire scheduling window that includes one or more selected chunks for each of the plurality of subframes.

13. The method of claim 10, wherein indicating in a downlink assignment index field of a downlink grant further comprises indicating in the downlink assignment index field one of a previous or a total number of downlink grants within a current downlink grant region.

14. The method of any one of claims 10 to 13, where the downlink grant region for each particular uplink grant comprises downlink grants within chunks associated with an entire scheduling window.

15. The method of any one of claims 10 to 14, where for the uplink grants, there is a one-to-one or a many-to-one mapping between the chunks, within an entire bandwidth of the resource space or an entire bandwidth of the plurality of chunks for a sub frame, where the mapping may be one of pre-defined or dynamic using a mapping rule known to both a user equipment and to a base station.

16. The method of any one of claims 10 to 15, further comprising encoding each downlink assignment index using (m) mod (4), where m indicates a previous or total number of downlink grants within the selected region.

17. The method of claim 16, further comprising comparing the value of a selected one of the downlink assignment indexes with (the previous or total number of received or detected downlink grants within the selected region) mod (4) to enable a user equipment to detect a case of a missing downlink grant.

18. The method ofany one of claims 10 to 17, wherein the downlink assignment index field comprises two bits for each of the uplink grant and the downlink grant.

19. A computer program, comprising: code for indicating in a downlink assignment index field in an uplink grant for a user equipment a total number of downlink grants within a downlink grant region comprising a portion of a resource space, wherein the resource space comprises a plurality of subframes, each subframe having a plurality of chunks; and code for indicating in a downlink assignment index field of a downlink grant for a user equipment a number of downlink grants in a selected region of the resource space; when the computer program is run on a processor.

20. The computer program according to claim 19, wherein the computer program is a computer program product comprising a computer-readable medium bearing computer program code embodied therein for use with a computer.

21. The computer program of claim 19, wherein indicating in a downlink assignment index field of a downlink grant further comprises indicating in the downlink assignment index field one of a previous or a total number of downlink grants within a current subframe over an entire bandwidth that includes all of the chunks for the current subframe.

22. The computer program of claim 19, wherein indicating in a downlink assignment index field of a downlink grant further comprises indicating in the downlink assignment index field one of a previous or a total number of downlink grants within a current one of the at least one chunks over an entire scheduling window that includes one or more selected chunks for each of the plurality of subframes.

23. The computer program of claim 19, wherein indicating in a downlink assignment index field of a downlink grant further comprises indicating in the downlink assignment index field one of a previous or a total number of downlink grants within a current downlink grant region.