US20130039272A1

US20130039272A1 - Method for data transmission and base station and user equipment using the same

Info

Publication number: US20130039272A1
Application number: US13/571,370
Authority: US
Inventors: Chun-Chia Chen
Original assignee: Industrial Technology Research Institute ITRI
Current assignee: Industrial Technology Research Institute ITRI
Priority date: 2011-08-10
Filing date: 2012-08-10
Publication date: 2013-02-14
Also published as: TW201308956A; TWI472202B; US8873491B2; TW201316732A; TW201320692A; US20130039295A1; US20130039297A1

Abstract

A method for data transmission, a base station using the same and a user equipment (UE) using the same are provided. According to an exemplary embodiment, the present disclosure provides a method of data transmission, adapted for a user equipment (UE), the method contains the steps of receiving from a base station signaling comprising a sub-frame which comprises a control region and a data region; decoding from the data region a first transport block indicated by a first downlink assignment from the control region; and decoding the first transport block to obtain a first control information, wherein the first control information includes a downlink assignment, an uplink grant, or an extended control region indicator.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefits of U.S. provisional application Ser. No. 61/522,050, filed on Aug. 10, 2011. The entirety of the above-mentioned patent applications is hereby incorporated by reference herein and made a part of this specification.

TECHNICAL FIELD

The present disclosure generally relates to a method for data transmission, a base station using the same and a user equipment (UE) using the same.

BACKGROUND

In current wireless broadband standards such as Third Generation Partnership Project Long Term Evolution (3GPP LTE), the control channel capacity usually is highly limited. Specifically, there may be about 10 Physical Downlink Control Channel (PDCCH) signaling which can be sent in one Transmission Time Interval (TTI) in a 10 MHz system bandwidth scenario, in which about at most 10 User Equipments (UEs) can be scheduled for either Downlink (DL) or Uplink (UL) data transmission. While dedicated UEs need to follow scheduling information carried by PDCCH, in fact a large proportion of Control Channel Elements (CCEs) has to be used for non-dedicated/common functions. For instance, about a total of 41 CCEs is available when 3 OFDM symbols are allocated for PDCCH, but out of the 41 available CCEs, up to 16 Control Channel Elements (CCEs) are commonly allocated for Common Search Space (CSS) including control functionalities such as System Information (SI), Paging, Random Access (RA), Transmission Power Control (TPC), and so like. This leaves only about 25 CCEs available for dedicated UE scheduling. For another example, in a scenario where 2 OFDM symbols are allocated for PDCCH, only about 10 CCEs out of a total of 25 CCEs are available for dedicated UE scheduling.
However, the channel capacity is further limited under the circumstance of Carrier Aggregation (CA). In Carrier Aggregation (CA), cross-carrier scheduling may be used to schedule resources on another serving cell and therefore reduce inter-cell interference in Heterogeneous Networks. In addition, cross carrier scheduling may be used to schedule resources on non-backward compatible carriers. For instance, when a wireless communication system is operating with non-backward compatible carriers, during a sub-frame in which the allocated frequency band for a first carrier (CC1) may contain data in the Physical Downlink Shared Channel (PDSCH) and a second carrier (CC2) may contain data in its PDSCH, the control region of a first carrier (CC1) may actually contain PDCCH for both CC1 and CC2 while no PDCCH or Physical Hybrid ARQ Indicator Channel (PHICH) or Physical Control Format Indicator Channel (PCFICH) would exist in the control region of CC2 in order to avoid interference to control region of other cells. For another example of non-backward compatible carriers, the non-backward compatible carrier is close to the backward compatible carrier and may only contain data region. The control region of the backward compatible carrier may contain control signaling for both data regions of backward and non-backward compatible carrier. This means that using carrier aggregation would further require more control channel capacity.
In a practical scenario, for example, the applications of instant communications (e.g. messages services and social networks) may have the characteristics of variant packet inter-arrival time, and small size of packet. In additional, the time of arrivals between packets may be large. If a scheme of periodic resource allocation is adopted, it would result in a waste of resource allocation if the scheduled period were short but would otherwise adversely affect interactivity if the period were long. For real time services such as gaming, video surveillance, remote control, and so like, tight delay and frequent transmissions of data having variable sizes are required. Also for machine type communication in general, such as machine-to-machine traffic, a large amount of small data traffic with variable sizes is required. Therefore, all that has been described necessitate a mechanism to reduce the control signal (e.g. PDCCH) overhead.
Semi-Persistent Scheduling (SPS) could be used to reduce the control signal overhead. For services involving a semi-static packet rate such as VoIP, SPS can be configured to reduce the control signal overhead. For this kind of service to be implemented, the timing and the amount of radio resources require predictability. The SPS enables radio resources to be semi-statically configured and allocated to a UE for a longer time period other than one sub-frame, and the SPS may avoid the need for transmitting specific downlink assignment messages or uplink grant messages over the PDCCH for each sub-frame. However, the SPS may not be suitable for other Internet applications such as social network applications since updating information on the social network website could not be easily predicted.

SUMMARY

Accordingly, the present disclosure is directed to a method for data transmission, a base station using the same and a user equipment (UE) using the same. According to an exemplary embodiment, the present disclosure provides a method of data transmission, adapted for a user equipment (UE), the method contains the steps of receiving from a base station signaling comprising a sub-frame which comprises a control region and a data region; decoding from the data region a first transport block indicated by a first downlink assignment from the control region; and decoding the first transport block to obtain a first control information.
According to an exemplary embodiment, the present disclosure provides a user equipment which has a transceiver and a processor. The transceiver transmits and receives wireless signals. The processor is coupled to the transceiver and is configured to receive from a base station signaling comprising a sub-frame which comprises a control region and a data region, decode from the data region a first transport block indicated by a first downlink assignment from the control region, and decode the first transport block to obtain a first control information.
According to an exemplary embodiment, the present disclosure provides a base station which contains a transceiver and a processor. The transceiver transmits and receives wireless signals. The processor is coupled to the transceiver and is configured to configure data comprising a sub-frame which comprises a control region and a data region, encode in the control region a first downlink assignment, encode in the data region a first transport block indicated by the first downlink assignment, and encode the first transport block to comprise a first control information.
The accompanying drawings are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the disclosure and, together with the description, serve to explain the principles of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a wireless communication system including an eNB communicating with at least one UEs in accordance with an exemplary embodiment.

FIG. 2 illustrates the contents of sub-frames of data used in the wireless communication system in accordance with an exemplary embodiment of the present disclosure.

FIG. 3A illustrates an example of the control information and data in a sub-frame.

FIG. 3B illustrates piggyback control information in a transport block according to an exemplary embodiment.

FIG. 3C illustrates using an extended control region.

FIG. 3D illustrates using piggyback control information to indicate the location of the extended control region according to an exemplary embodiment.

FIG. 4 is a process flow chart illustrating a method of using piggyback control information for data transmission according an exemplary embodiment.

FIG. 5 illustrates various approaches of allocating piggyback control information elements in a MAC PDU according to an exemplary embodiment.

FIG. 6 is a process flow chart illustrating a process of piggyback control information in a transport block for a downlink assignment according to an exemplary embodiment.

FIG. 7 is a flow chart illustrating parallel a PDCCH assignment and a piggyback downlink assignment according to an exemplary embodiment.

FIG. 8 is a process flow chart illustrating a process of piggyback control information in the transport block for an uplink grant according to an exemplary embodiment.

FIG. 9 is a flow chart illustrating parallel a PDCCH assignment and a piggyback uplink grant according to an exemplary embodiment.

FIG. 10 illustrates a process of piggybacking control information for a combination of DL assignment and UL grant according to an exemplary embodiment.

DETAILED DESCRIPTION OF DISCLOSED EMBODIMENTS

In this disclosure, 3GPP-like keywords or phrases are used merely as examples to present inventive concepts in accordance with the present disclosure; however, the same concept presented in the disclosure can be applied to any other systems such as IEEE 802.11, IEEE 802.16, WiMAX, sensor network and so like by persons of ordinarily skilled in the art.
Throughout the disclosure, the term PDCCH is used to represent the a control region or a downlink control channel to indicate downlink (DL)/uplink (UL) resource allocation assignment, the same concept by the present disclosure can also be applied to other downlink control channels including DL-MAP, UL-MAP, MBS-MAP, and so like through simple analogy.
The term “eNodeB” or “eNB” in this disclosure may be, for example, a base station (BS), a Node-B, an advanced base station (ABS), a base transceiver system (BTS), an access point, a home base station, a relay station, a scatterer, a repeater, an intermediate node, an intermediary, and/or satellite-based communication base stations, remote radio header (RRH), and so like.
The term “user equipment” (UE) in this disclosure may be, for example, a mobile station, an advanced mobile station (AMS), a server, a client, a desktop computer, a laptop computer, a network computer, a workstation, a personal digital assistant (PDA), a tablet personal computer (PC), a scanner, a telephone device, a pager, a camera, a television, a hand-held video game device, a musical device, a wireless sensor, a smart phone, and so like. In some applications, a UE may be a fixed computer device operating in a mobile environment, such as a bus, train, an airplane, a boat, a car, and so like.
Presently, with applications using small data packets with diverse data inter-arrival time on the rise, the control region in a sub-frame carrying control information may require more space in order to accommodate the increase of the control signaling. However, since the PDCCH capacity in the control region is highly limited, there is a need to either reduce the PDCCH overhead or to increase the control region space. In this present disclosure, a method for data transmission and a base station and a user equipment using the same method are proposed to enhance the data transmission by piggybacking control information in the transport block (TB). Here, the transport block may refer to data in the data region of wireless signals transmitted from a base station to a UE.
FIG. 1 illustrates a wireless communication system according to an exemplary embodiment. The wireless communication system includes an eNB (101) in communication with at least one UEs (103, 105, . . . 10x) in accordance with a wireless communication standard. Each UE contains, for example, at least a transceiver circuit (111), an analog to digital (A/D)/digital to analog (D/A) converter (113), and a processing circuitry (115). The transceiver circuitry (111) is capable of transmitting uplink signal and/or receives downlink signal wirelessly. The transceiver circuitry (111) may also perform operations such as low noise amplifying, impedance matching, frequency mixing, up or down frequency conversion, filtering, amplifying, and so like. The transceiver circuitry (111) also includes an antenna unit (not shown in FIG. 1). The analog-to-digital (A/D)/digital-to-analog (D/C) converter (113) is configured to convert from analog signal format to digital signal format during downlink signal processing and digital signal to analog signal during uplink signal processing. The processing circuitry (115) is configured to process digital signal and to perform procedures of the proposed method for data transmission in accordance with exemplary embodiments of the present disclosure. Also, the processing circuitry (115) may include a memory unit (not shown in FIG. 1) to store data or record configurations assigned by the eNB 101. The eNB (101) contains similar elements which lead to the converted digital signal to be processed by its processing circuitry (117) so as to implement the method for data transmission in accordance with exemplary embodiments of the present disclosure.
FIG. 2 illustrates the contents of a sub-frame used in the wireless communication system in accordance with an exemplary embodiment of the present disclosure. According to FIG. 2, there could be, for example, 10 sub-frames per frame (200), and each sub-frame is a transmission time interval (TTI). Within each sub-frame, in sub-frame #0 (201) for example, there may be a control region (210) and a data region (220). Conventionally, the control region (210) may include PDCCH which contains resource allocation information such as DL assignment and UL grant. Specifically, the Downlink Control Information (DCI) in PDCCH provides resource allocation information for downlink or uplink. The data region (220) may include PDSCH which is configured to carry numerous transport blocks (TB) (230). It is possible that the control signal overhead can be overwhelming when there are a lot of demands for dynamic downlink or uplink resource assignment. Therefore, one of the concepts behind piggyback control information is to carry DCI information in the transport blocks (TB). Also, another one of the concepts behind piggyback control information is to carry the location information of an extended control region in the TB. A base station or eNB may transmit DL data to a UE through a PDCCH and PDSCH or assign UL resource on a PUSCH to a UE through a PDCCH. A UE may monitor a DL channel, e.g., PDCCH and PDSCH, in a sub-frame to obtain the control information and data. FIG. 3A illustrates an example of the control information and data in a sub-frame transmitted from an eNB. Upon a UE receiving from a base station DL signaling containing PDCCH (32) and PDSCH (34), the DCI information (30) could be obtained by the UE through blindly decoding the PDCCH. The PDCCH (32) may be referred to as the control region and PDSCH (34) may be referred to as payload region, and a MAC PDU in a sub-frame may also be known as a packet data unit or a packet data or a radio resource. The DCI information obtained by the UE may indicate the location of a TB (36) which contains data for the UE. In another example, the DCI information may indicate an uplink resource for UE to transmit UL data.
FIG. 3B illustrates piggybacking control information in a TB. Upon a UE receiving from a base station DL signaling containing PDCCH (32) and PDSCH (34), the DCI information (30) could be obtained by the UE through blindly decoding the PDCCH. The DCI information obtained by the UE may indicate the location of a TB (36) which contains data for the UE. The TB (36) may contain control information for resource allocation, namely DCI information, related to an uplink grant or a downlink assignment. In other words, the control information which would normally be in the PDCCH (32) is piggybacked onto the PDSCH region (34), namely a TB (36) in the data region. The TB may contain one or more DCI (40) information for downlink resource assignment or/and one or more DCI (40) information for uplink resource assignment. If the DCI (40) information contains the downlink resource assignment, the downlink resource assignment may indicate a TB (43) in this sub-frame or another TB in the future sub-frame. The UE may then acquire a TB (43) based on the DCI (40) information. The TB (43) may contain another set of piggyback control information as well. Alternatively, if the DCI (40) information contains the UL resource assignment, the UE may store the UL resource assignment, namely UL grant, and then will transmit UL data based on the UL grant in a future sub-frame.
FIG. 3C illustrates an example of using an extended control region, namely extended physical downlink control channel (E-PDCCH), for carrying DCIs. The PDSCH (34) may contain the extended physical downlink control channel (E-PDCCH) (45) which is an extended control region used to carry control signaling such as DCIs. When the UE successfully decodes DCI(s) (46) in the E-PDCCH, UE would discover that the DCI is for a DL resource assignment or for an UL resource assignment. If the DCI (40) indicates a DL resource, then the UE decodes the TB (47) based on the DCI information (46) to obtain the DL data. Alternatively, if the DCI (46) indicates an UL resource, then the UE stores the DCI (46) information, namely UL grant, and will transmit the UL data based on the UL grant in the future sub-frame.
FIG. 3D illustrates piggyback control information to indicate the location information of the extended control region. The UE first blindly decodes the PDCCH (32) to obtain the DCI (30), which subsequently indicates the location of a TB (36). The UE then decodes the TB (36) according to the parameters in the DCI (30). Upon the successfully decoding of the TB (36), an extended control region indicator or an E-PDCCH indicator (49) might be found in the TB (36). The E-PDCCH indicator indicates the location of an E-PDCCH region in the PDSCH (34) of a sub-frame. E-PDCCH may be in the current sub-frame or in the future sub-frame based on predetermination or the parameters in the extended control region indicator. Next, the UE may blindly decode the E-PDCCH (45) which may contain a set of DCIs (46). A DCI (46) for downlink resource assignment may indicate a location of another TB (47). The TB (47) may also contain another set of piggyback control information. The UE then decodes the TB (47) based on the parameters in DCI (46) to obtain the DL data and maybe another piggyback control information which may indicate an uplink grant or a downlink assignment. The UE would deal with the UL grant or the DL assignment as the previous description. Alternatively, a DCI (46) for UL resource assignment may indicate the UL resource information, namely UL grant. The UE stores the UL grant and then will transmit UL data in the future time. An extended control region could be shared by multiple UEs. There may have multiple extended control regions in a data region (PDSCH) of a time slot.
A TB indicated by a piggyback control information may be shared by different UEs. In other words, the location of a TB may be indicated by multiple piggyback control information from other different TBs received by different UEs. This one TB may contain data for one UE. The UEs may try to decode the TB. When decoding successfully, the UE stores data and forwards the data to an upper layer. The UE may send an ACK to the base station or eNB. When decoding unsuccessfully, the UE may discard this piggyback control information.
In another exemplary embodiment, this one TB indicated by multiple piggyback control information may contain multiple data for multiple UEs with each data designated for a different UE. The UEs may decode this TB and subsequently find the corresponding data in the TB for each UE based on the UE indication information in the TB or based on a predetermined location. For example, UE IDs or a bitmap in the TB header indicates whether or not the corresponding data exists in this TB. Furthermore, the data size information for each UE may be predetermined or contained in this TB header.
FIG. 4 is a process flow chart illustrating a method for data transmission of an exemplary embodiment. In step S401, a UE receives PDCCH and PDSCH. Next in step S403, the UE blindly decodes PDCCH to obtain DCI information with assignment information which is assigned by the base station to the UE. Next, in step S405, the UE locates a TB based on the DCI information, and then after the TB is located, the TB is decoded according to the assignment information in the DCI. Next, in step S407, assuming that the TB is successfully decoded, MAC (Media Access Control) PDU (Protocol Data Unit) can be obtained by the UE from the TB. The UE would then be able to obtain piggyback control information from the MAC PDUs of the TB. Next, in step S409, the obtained control information may be stored in the memory of the UE. The control information may be used for a downlink resource assignment at the current time or in a future time, may be used for an uplink resource assignment at the current time or in a future time, or may be used for indicating a location of an extended control region at the current time or in a future time. In step S411, the downlink assignment, the uplink assignment, or the extended control region indicator is processed.
A TB may contain one or multiple Media Access Control Protocol Data Units (MAC PDU) or PDU. A MAC PDU is also referred to a packet data unit. In an embodiment of the disclosure, the piggyback control information may be placed inside the MAC control elements (MAC CE) of a MAC PDU. A MAC CE is also referred to a part of the payload region of a packet data unit. The piggyback control information may be a downlink (DL) assignment information for the DL TB or an uplink grant information for the UL resource or an extended control region indicator for the location of extended control region. A TB may contain one or more piggyback control information. That is, a TB may contain one or more piggyback control information for DL assignment, one or more piggyback control information for UL grant, and one or more piggyback control information for extended control region indicators. A piggyback control information in the TB may indicate an DL assignment or an UL grant or an extended control region indicator in the current time slot or in the future time slot. For example, a type indicator could be used in a MAC CE to indicate that the piggyback control information in a TB for a specific UE is a DL assignment or an UL grant or an extended control region indicator.
In some embodiments, a type indicator may be placed in a MAC sub-header or in the header region of a packet data unit. A MAC header is also referred to the header region of a packet data unit. A header region of a packet data unit may contain one or more sub-headers. FIG. 5 illustrates indicators in MAC sub-header or in MAC CE according to an exemplary embodiment. According to FIG. 5, a MAC PDU (500) contains a MAC header (510), a few blocks of MAC CE (532) followed by payloads of data packets including MAC Service Data Units (SDU) (534), and optional padding (536).
A MAC header (510) may contain numerous MAC sub-headers (520). A MAC sub-header may indicate a corresponding MAC CE or a MAC SDU. According to an exemplary embodiment, there may be three different formats for a MAC sub-header. For the first format (522) of a MAC sub-header, there are 8 bits of information. R is a reserved bit. E is an extension field which is a flag indicating whether more MAC sub-header fields are present in a MAC header or not. The Logic Channel identification (LCID) (5221) field identifies the logic channel instance of the corresponding MAC SDU or the type of the corresponding MAC CE or padding.
For the second format (524) of MAC sub-header, there is an additional byte of a bit F and a 7 bit length field L, where F is the field which indicates the size of the length field (L), and L is the length field indicating the length of the corresponding MAC SDU or variable-sized MAC CE in bytes. If the size of the MAC SDU or variable-sized MAC control element is less than 128 bytes, the value of the F field is set to 0, otherwise it is set to 1.
For the third format (526) of the MAC sub-header, the value of the F field is set to 1 and the L field is lengthened as there are a total of 15 bits available for the L length field.
In another embodiment, an LCID field may also be used as a type indicator to indicate a DL assignment, an UL grant, or an extended control region indicator in a MAC CE. For example, one LCID value in the LCID field of a MAC sub-header can be used to indicate a DL assignment in a MAC CE, another LCID value can be used to indicate an UL grant in a MAC CE, and another one LCID value can be used to indicate an extended control region indicator in a MAC CE.
In an exemplary embodiment, if an LCID value is shared between a DL assignment and an UL grant, an indicator is further needed for indicating that the current piggyback control information in a MAC CE is a DL assignment or an UL grant. For example, an R bit in MAC subheader can be further used as the indicator. For example, R=0 may indicate a DL assignment, and R=1 may indicate an UL grant. For another example, a type indicator in the piggyback control information in a MAC CE may be used. In another exemplary embodiment, if an LCID value is shared among a DL assignment, an UL grant and an extended control region indicator, a type indicator is further needed for indicating that the current piggyback control information in a MAC CE is a DL assignment, an UL grant or an extended control region indicator. For example, two R bits in MAC sub-header can be further used to indicate that the current piggyback control information in a MAC CE is a DL assignment, an UL grant or an extended control region indicator. For example, RR=01 may indicate a DL assignment, RR=10 may indicate an UL grant, and RR=11 may indicate an extended control region indicator. For another example, one R bit in MAC subheader can be further used to indicate that the current piggyback control information in a MAC CE is a resource allocation (DL assignment or UL grant) or extended control region indicator. Furthermore, a type indicator in the piggyback control information in a MAC CE may be used to indicate that the current piggyback control information in a MAC CE is a DL assignment or an UL grant. Therefore, the type indicator is shared among a logical channel identification and two reserve bits of sub-headers of the header region to indicate a downlink assignment, an uplink grant, or an extended control region indicator.
For a DL assignment in a piggyback control information, the DCI information may include the following parameters: a type indicator for indicating a DL assignment, a carrier indicator to indicate one of multi-carriers, resource allocation header, resource block assignment, modulation and coding scheme (MCS), HARQ process number, new data indicator, redundancy version, TPC command for PUCCH, downlink assignment index, and timing indicator (k), where k is an integer greater than or equal to 0, and in some cases, k may be 0 to indicate the TB is for the current time slot. Timing indicator (k) indicates a sub-frame number. In other words, a downlink assignment under the method for data transmission with the piggyback control information may indicate that a TB is for the current time slot or for a future time slot. If the timing indicator (k) field is absent, the DL assignment is for the current time slot or for a future time slot with a predetermined time period. If a type indicator is in MAC sub-header, the type indicator in the DCI information may be not needed. The aforementioned parameters such as the type indicator, the carrier indicator, and the timing indicator (k) are novel indicators proposed in accordance with an exemplary embodiment.
For an UL grant in a piggyback control information, the DCI information may include the following parameters: a type indicator for indicating an UL grant, a carrier indicator, a flag for format0/format1A differentiation, a frequency hopping flag, a resource block assignment and a hopping resource allocation, a modulation and coding scheme and redundancy version, a new data indicator, a TPC command for scheduled physical uplink shared channel (PUSCH), cyclic shift for demodulation reference signal (DM RS) and optical carrier component (OCC) index, UL index, Downlink Assignment Index (DAD, channel state information (CSI) request, sounding reference signal (SRS) request, resource allocation type and timing indicator (n), where n is an integer greater than or equal to 0. The timing indicator indicates that piggyback control information for UL resource assignment is for the current time slot or for a future time slot. If a type indicator is in MAC sub-header, the type indicator in the DCI information may be not needed. If the timing indicator (n) field is absent, the UL grant is for a future time slot with a predetermined time period. The aforementioned parameters listed for UL grant such as the type indicator, the carrier indicator and the timing indicator (n) are novel indicators proposed according to an exemplary embodiment.
A base station or an eNB may start or stop using piggy back control information for any UE based on statistics of UE data traffic and/or the usage of PDCCH control region. A base station is likely to start piggy back control information as the UE data traffic experiences an increase or as the usage of PDCCH control region is high.
For re-transmission, a UE may send ACK if the UE correctly decodes the data, and a UE may not send NACK if the UE does not correctly decode the data. If a base station does not receive an ACK from the UE, the base station may re-transmit the same resource allocation assignment according to conventional rules. In the case of piggyback control information for which an extended control region, or E-PDCCH is used, the downlink transmission only carrying extended control region information may not need HARQ, and the UE may not need to provide ACK or NACK feedback.
The eNB or base station may transmit the DL data which is indicated by the piggyback control information to one of the UEs, and the eNB may transmit other DL data for the same UE by normal PDCCH assignment at the same time slot. In other words, the base station can configure a UE for piggyback control information in conjunction with normal PDCCH assignment. Also, the piggyback control information operation and the normal control information operation for each UE could either be performed in parallel or exclusive at any time slot.
FIG. 6 is a process flow chart illustrating the process of piggybacking control information operation in the TB for a downlink resource assignment according to an embodiment. An exemplary embodiment of the procedure of DL assignment is as follows: The DL assignment can be either from PDCCH or from the piggyback control information in a TB previously received. In step S601, an UE receives PDCCH and PDSCH at time t. In step S603, if an UE finds a DL assignment in the PDCCH, the UE executes step S605, otherwise the process ends. In the step S605, the UE decodes TB in PDSCH based on the DL assignment information which is received in this PDCCH, or is from a piggyback control information for a DL assignment received in this time slot or is from a stored DL assignment received in the previous time slot. The UE then processes this TB to obtain packet data and the piggyback control information if any from this TB. If the packet data is found in this TB, the UE may forward the data to an upper layer. In step S617 the UE determines if a stored DL assignment obtained from the previously received TB indicates DL resource for this current time slot. If the determination results in a yes in the step S617, then in step S619, the UE receives PDSCH and may also receive PDCCH for normal DL/UL assignment. Then, in step S605 the UE decodes the TB based on the stored DL assignment information.
In step S607, the UE would attempt to find piggyback control information for DL assignment in this TB. If no piggyback control information for DL assignment in the TB is found in the step S607, then the process for handling DL assignment ends. If a DL assignment in the TB is found by the UE in the step S607, then in step S609 the UE determines if the DL assignment is for the current time slot (e.g., the timing indicator field, k=0 or the field is absent). If the DL assignment is for the current time slot, then the UE processes the TB based on this DL assignment as the procedure loops back to step S605.
If however back in the step S609, the resource allocation is not for the current time slot but for a future time slot (e.g., t+k, where k is a number greater than or equal to zero and is a multiple of a sub-frame period), then in step S611 the UE stores the DL assignment as the UE would need to receive PDSCH at time t+k. Note that the parameter k may be predetermined or defined in the DL assignment information, i.e., the timing indicator. The UE would then process the TB in PDSCH at time t+k based on the stored DL assignment information. The processing of the TB would include for UE receiving downlink data, or for base station transmitting downlink data.
FIG. 7 is a flow chart illustrating parallel PDCCH assignment and piggyback assignment according to an exemplary embodiment. An eNB may transmit more than one TB at the same time slot to a UE by PDCCH assignment and piggyback assignment. The UE on the other hand may receive more than one TB at the same time slot based upon PDCCH assignment and piggyback assignment. An exemplary embodiment of the parallel PDCCH assignment and piggyback assignment procedure is as follows.
In step S701, a UE receives PDCCH and PDSCH. In step S703, if the UE finds a DL assignment in the PDCCH, then in step S705, the UE would decode a TB in PDSCH based on the DL assignment information from the PDCCH and then processes this TB and executes step S707. If in step S703, the UE does not find a DL assignment in PDCCH, then no TB is indicated as step S707 would be executed instead. In step S707, the UE determines if a stored DL assignment obtained from a previous piggyback TB block indicates a DL resource in this current time slot. If the DL resource is for this time slot, then in step S709 the UE decodes a TB in PDSCH based on the DL assignment information and then processes this TB. If there is not a stored DL assignment in step S707, then the UE executes step S711.
Next, in step S711, if one or more DL assignments in these decoded TBs is found, then in step S713, the UE checks if the DL assignment(s) is for this time slot (e.g., the timing indicator field, k=0 or the field is absent). If the DL assignment is for the current time slot, then the UE processes the TB based on this DL assignment as the procedure loops back to step S709, since the TB decoded back in step S709 could contain yet another DL resource assignment. If however in the step S713, the resource allocation is not for the current time slot but for a future time slot (e.g., t+k, where k is a number greater than or equal to zero and is a multiple of a sub-frame period), then in step S715 the UE stores the DL assignment as the UE would need to receive PDSCH at time t+k. Note that the parameter k may be predetermined or defined in the DL assignment information, i.e., the timing indicator. The UE would then process the TB in PDSCH at time t+k based on the stored DL assignment information.
FIG. 8 is a flow chart illustrating the process of piggybacking control information operation in the TB for an UL resource assignment according to an embodiment. Referring to FIG. 8, the procedure of an UL grant is described as follows: In step S801, an UE receives PDCCH and PDSCH at time t. Next, in step S803, the UE determines whether a DL assignment in PDCCH is found. If not, the process ends. Otherwise, the UE continues to determine if a DL assignment in PDCCH is found. If the determination result is yes in the step S803, the UE continues to execute step S805. In the step S805 the UE decodes TB in PDSCH based on the DL assignment information from the PDCCH and then process this TB. In step S807, if the UE finds an UL grant in this TB, then in step S809 UE stores the UL grant for future uplink. In step S811 which occurs at time t+n, in which n stands for the total time for n numbers of sub-frames to elapse, UE prepares to transmit a TB in PUSCH at time t+n according to the information in the stored UL grant. It is noted that the number n could be non-zero since the UE could always wait for a number of sub-frames to elapse before transmitting the TB. In addition, the number n may be pre-determined or obtained from the timing indicator in the UL grant. In the step S813, the UE transmits a TB in PUSCH based on the stored UL grant information at time t+n.
FIG. 9 is a flow chart illustrating parallel PDCCH assignment and piggyback control information for uplink resource assignment according to an exemplary embodiment. The steps S901 to S909 and step S913 correspond to steps S801 to S809 and step S813 respectively, and therefore the explanation for these steps is not repeated. Comparing with step S811, in step S911 the UE may need to process more than one UL grant, i.e., the UE may have UL grant, which indicates the UL resource for this time slot, from PDCCH or from a piggyback control information. The other difference between FIG. 8 and FIG. 9 is situated in two additional steps, namely S915 and S917. In S915, the UE blindly decode DCI in the PDCCH for an UL grant. If an UL grant is found in PDCCH, then the UE processes this UL grant in parallel with the piggyback uplink assignment found in the steps S901 to S909. In step S917, an UL grant found in PDCCH is then stored and is to be transmitted in PUSCH in the step S913. In step S913, the UE may transmit more than one UL data (or TB) on PUSCH according to the stored UL grants which may from the PDCCH or from the piggyback control information.
Furthermore, the process of DL resource assignment from PDCCH or piggyback control information and the process of UL resource assignment from PDCCH or piggyback control information could both be processed in parallel. FIG. 10 is a flow chart illustrating an exemplary embodiment for the combination of DL assignment and UL grant from PDCCH or from piggyback control information. Since this procedure is similar to the procedure described by FIG. 6, FIG. 8, and their corresponding written descriptions, this process flow is quickly described. The steps of S1001, S1003, S1005, S1007, S1009, and S1011 would be respectively identical to S601, S603, S605, S607, S609, and S611 as illustrated in FIG. 6. However, in step S1013 of FIG. 10, an UL grant in the decoded TB could be found instead of a DL resource allocation. In this case, the handing for the UL grant by the UE in steps S1013, S1015, S1021, and S1023 would be respectively identical S807, S809, S811, and S813 of FIG. 8. Therefore, the description is not repeated.
The procedures of executing downlink assignment, uplink assignment, parallel processing of PDCCH assignment and piggyback assignment, and processing DL assignment and UL grant in combination for the exemplary embodiments as described in FIGS. 3B, 3C, and 3D are similar and are not repeated again. In addition, the DL/UL assignment also could be obtained from the extended control region (E-PDCCH). So the procedure of the DL/UL assignment from PDCCH or piggyback control information could also be combined with a pre-determined extended control region or an extended control region indicated by the piggyback control information. The combined procedures are similar to the procedures of the exemplary embodiments and are not repeated again.
Even though the examples of processing downlink and uplink assignment through piggyback control information are disclosed from a UE's point of view, the implementation of these processes for a base station would be apparent for a person of ordinarily skilled in the art.
In view of the aforementioned descriptions, the present disclosure is able to improve data transmission by piggybacking control information in the TB. Piggyback control information in the data region of a sub-frame could provide pre-allocated resource for both DL or UL resource and thus reduce the packet delay. In addition, piggyback control information can provide dynamic interval SPS (Semi-Persistent Scheduling)-like resource and robust control information in PDSCH rather than in PDCCH. Since the same data may be in two resource blocks, the transmit diversity gain can be increased when one data may be assigned by normal PDCCH and the other may be assigned by piggyback control information. Furthermore, the embodiments of the present disclosure allow an UE to process multiple DL TBs and multiple UL resource blocks in a time slot. Extend Control region could be also taken advantage as it is used for allocating DL resource or UL resource by the piggyback control information.
It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the disclosed embodiments without departing from the scope or spirit of the disclosure. In view of the foregoing, it is intended that the disclosure cover modifications and variations of this disclosure provided they fall within the scope of the following claims and their equivalents.

Claims

1. A method of data transmission, adapted for a user equipment (UE), the method comprising:

receiving from a base station signaling comprising a sub-frame which comprises a control region and a data region;

decoding from the data region a first transport block indicated by a first downlink assignment from the control region; and

decoding the first transport block to obtain a first control information.

2. The method of claim 1, wherein the first control information comprises a downlink assignment, an uplink grant, or an extended control region indicator.

3. The method of claim 1, wherein claim 1 further comprises:

if the first control information indicates a downlink assignment, obtaining a second transport block according to the first control information; and

processing the second transport block.

4. The method of claim 3, wherein the second transport block may be shared by multiple UEs.

5. The method of claim 3, wherein the second transport block contains multiple data for multiple UEs with each data designated for a different UE.

6. The method of claim 3 wherein the step of processing the second transport block comprises:

decoding the second transport block;

obtaining a second control information from the second transport block; and

processing the second control information according to the content of the second control information.

7. The method of claim 1, wherein if the first control information indicates an extended control region indicator, claim 1 further comprises:

obtaining an extended control region according to the first control information;

decoding the extended control region to obtain a second control information;

if the second control information indicates a downlink assignment, obtaining a second transport block according to the second control information and processing the second transport block; and

if the second control information indicates an uplink grant, storing the uplink grant and transmitting data according to the uplink grant.

8. The method of claim 1, wherein the step of decoding the first transport block to obtain the first control information, comprises:

decoding the first transport block to obtain packet data units comprising a header region and a payload region, wherein the header region comprises a type indicator, and the payload region comprises a control information.

9. The method of claim 8, wherein the control information comprises at least one selected from the group consisting of:

a type indicator to indicate an uplink grant, a downlink assignment, and an extended control region indicator;

a carrier indicator to indicate one of multi-carriers; and

a timing indicator to indicate a sub-frame number.

10. The method of claim 8, wherein a logical channel identification (LCID) in a logical channel identification field of the header region is used as the type indicator which indicates a downlink assignment, an uplink grant, or an extended control region indicator.

11. The method of claim 8, wherein the type indicator is in two reserve bits of sub-headers of the header region to indicate a downlink assignment, an uplink grant, or an extended control region indicator.

12. The method of claim 8, wherein the type indicator is shared among a logical channel identification and two reserve bits of sub-headers of the header region to indicate a downlink assignment, an uplink grant, or an extended control region indicator.

13. The method of claim 1 further comprises:

if the first control information indicates a downlink assignment received at time t, decoding a second transport block at time t+k according to the first control information, wherein k is predetermined or is a value of a timing indicator in the first control information, and processing the second transport block at time t+k.

14. The method of claim 13 further comprises:

receiving a second downlink assignment at time t+k from decoding the control region;

decoding a third transport block according to the second downlink assignment; and

processing the third transport block.

15. The method of claim 1, further comprises:

if the first control information indicates an uplink grant received at time t, transmitting an uplink data at time t+n according to the first control information, wherein n is predetermined or is a value of a timing indicator in the first control information.

16. The method of claim 15, further comprising:

receiving a second downlink assignment at time t+n from decoding the control region;

decoding a second transport block according to the second downlink assignment; and

processing the second transport block and transmitting the uplink data according to the first control information.

17. A user equipment (UE), comprising:

a transceiver, configured to transmit and receive wireless signals; and

a processor, coupled to the transceiver, configured to:

receive from a base station signaling comprising a sub-frame which comprises a control region and a data region;

decode from the data region a first transport block indicated by a first downlink assignment from the control region; and

decode the first transport block to obtain a first control information.

18. The UE of claim 17, wherein the first control information comprises a downlink assignment, an uplink grant, or an extended control region indicator.

19. The UE of claim 17, wherein if the first control information indicates a downlink assignment, the processor is further configured to:

obtain a second transport block according to the first control information; and

process the second transport block which may comprise another control information.

20. The UE of claim 19, wherein the second transport block may be shared by multiple UEs.

21. The UE of claim 19, wherein the second transport block contains multiple data for multiple UEs with each data designated for a different UE.

22. The UE of claim 17 wherein if the first control information indicates an extended control region indicator, the processor is further configured to:

obtain an extended control region according to the first control information;

decode the extended control region to obtain a second control information;

if the second control information indicates a downlink assignment, obtain a second transport block according to the second control information and processing the second transport block; and

if the second control information indicates an uplink grant, store the uplink grant and transmit data according to the uplink grant.

23. The UE of claim 17, wherein the processor is configured to decode the first transport block to obtain the first control information comprises:

24. The UE of claim 23, wherein the control information comprises at least one selected from the group consisting of:

a carrier indicator to indicate one of multi-carriers; and

a timing indicator to indicate a sub-frame number.

25. The UE of claim 23, wherein the type indicator is in a logical channel identification (LCID) field of the header region which indicates a downlink assignment, an uplink grant, or an extended control region indicator.

26. The UE of claim 23 wherein the type indicator is in two reserve bits of sub-headers of the header region to indicator a downlink assignment, an uplink grant, or an extended control region indicator.

27. The UE of claim 23, wherein the type indicator is shared among a logical channel identification and two reserve bits of sub-headers of the header region to indicate a downlink assignment, an uplink grant, or an extended control region indicator.

28. The UE of claim 17, wherein the processor is further configured to:

receive a second transport block at time t+k according to the first control information if the first control information indicates a downlink assignment received at time t, wherein k is predetermined or is a value of a timing indicator in the first control information, and process the second transport block.

29. The UE of claim 28 further wherein the processor further configured to:

receive a second downlink assignment at time t+k from decoding the control region;

decode a third transport block according to the second downlink assignment; and

process the third transport block.

30. The UE of claim 17, wherein the processor is further configured to:

transmit an uplink data at time t+n according to the first control information if the first control information indicates an uplink grant received at time t, wherein n is predetermined or is a value of a timing indicator in the first control information.

31. The UE of claim 30, wherein the processor further configured to:

receive a second downlink assignment at time t+n from decoding the control region;

decode a second transport block according to the second downlink assignment; and

process the second transport block and transmit the uplink data according to the first control information.

32. A base station comprising:

a transceiver, configured to transmit and receive wireless signals; and

a processor, coupled to the transceiver, configured to:

configure data comprising a sub-frame which comprises a control region and a data region;

encoding in the control region a first downlink assignment;

encoding in the data region a first transport block indicated by the first downlink assignment; and

encoding the first transport block to comprise a first control information.

33. The base station of claim 32, wherein the first control information comprises a downlink assignment, an uplink grant, or an extended control region indicator.

34. The base station of claim 32, wherein if the first control information comprises a downlink assignment, according to the first control information, the processor is further configured to encode in the data region the second transport block which may comprise another control information.

35. The base station of claim 34, wherein the second transport block may be shared by multiple UEs.

36. The base station of claim 34, wherein the second transport block contains multiple data for multiple UEs with each data designated for a different UE.

37. The base station of claim 32, wherein if the first control information comprises an extended control region indicator, the processor is further configured to:

encode a second control information in the extended control region which is indicated by the first control information; and

if the second control information indicates a downlink assignment, encode in the data region a second transport block according to the second control information.

38. The base station of claim 32, wherein the processor is configured to encode the first transport block to comprise the first control information comprises:

encoding in the first transport block packet data units comprising a header region and a payload region, wherein the header region comprises a type indicator, and the payload region comprises a control information.

39. The base station of claim 38, wherein the control information comprises at least one selected from the group consisting of:

a type indicator to indicate an uplink assignment, a downlink assignment, and an extended control region indicator;

a carrier indicator to indicate one of multi-carriers; and

a timing indicator to indicate a sub-frame number.

40. The base station of claim 38, wherein the type indicator is in a logical channel identification (LCID) field of the header region which indicates a downlink assignment, an uplink grant, or an extended control region indicator to indicate the type of the control information.

41. The base station of claim 38, wherein the type indicator is in two reserve bits of sub-headers of the header region to indicator a downlink assignment, an uplink grant, or an extended control region indicator to indicate the type of the control information.

42. The base station of claim 38, wherein the type indicator is shared among a logical channel identification and two reserve bits of sub-headers of the header region to indicate a downlink assignment, an uplink grant, or an extended control region indicator.

43. The base station of claim 32, wherein the processor is further configured to:

transmit a second transport block encoded in the data region at time t+k according to the first control information when the first control information indicates a downlink assignment transmitted at time t, wherein k is predetermined or is a value of a timing indicator in the first control information.

44. The base station of claim 43, wherein the processor is further configured to:

transmit a second downlink assignment encoded in the control region at time t+k;

encode in the data region a third transport block according to the second downlink assignment; and

transmit the third transport block.

45. The base station of claim 32, wherein the processor further configured to:

receive an uplink data at time t+n according to the first control information if the first control information indicates an uplink grant transmitted at time t, wherein n is predetermined or is a value of a timing indicator in the first control information.

46. The base station of claim 45, wherein the processor further configured to:

transmit a second downlink assignment encoded in the control region at time t+n;

encode in the data region a second transport block based on the second downlink assignment; and

transmit the second transport block and receive the uplink data according to the first control information.