Methods for repetition design

Methods and apparatus are provided for repeated transmission. In one novel aspect, the RV sequence is selected from a predefined set of RV sequences for the repeated transmission. In one embodiment, the one or more RV values in the selected RV sequence are repeatedly used for the repeated transmission, by applying each RV value one by one to one block of repetitions cyclically, wherein the number of repetition in the block is determined by the repetition number and the length of the RV sequence. In another embodiment, the one or more RV values in the selected RV sequence are repeatedly used for the repeated transmission, by applying each RV value one by one to one repetition cyclically. In one embodiment, the RV value and the scrambling sequences are the same for the repetition blocks and a symbol level combination is applied.

TECHNICAL FIELD

The disclosed embodiments relate generally to wireless communication, and, more particularly, to repetition design.

BACKGROUND

Third generation partnership project (3GPP) and Long Term Evolution (LTE) mobile telecommunication systems provide high data rate, lower latency and improved system performances. Such systems are optimized for regular data communications, wherein there is no need for repeatedly retransmissions. However, in some situations, repeatedly retransmissions are needed. For example, some UEs, in the basements of residential buildings or locations shielded by foil-backed insulation, metalized windows, or traditional thick-walled building construction, may experience significantly larger penetration losses on the radio interface than normal LTE devices. More resources/power is needed to support these UEs in the extreme coverage scenario. Repetition has been identified as a common technique to bridge the additional penetration losses than normal LTE devices. However, issues remain for the repeated transmission. For example, a same symbol sequence generated from an information packet is repeatedly transmitted in each repetition, or different symbol sequences generated from the information packet are transmitted within different repetitions. Further, whether there are multiple repetitions within one time block at time domain. A new mechanism for repeated transmissions or retransmissions is needed.

SUMMARY

Methods and apparatus are provided for repeated transmission. In one novel aspect, the RV sequence is selected from a predefined set of RV sequences for the repeated transmission. In one embodiment, the UE obtains a repetition configuration, wherein the repetition configuration configures each repetition for repeatedly transmitted information packets. The UE determines a repetition time interval (RTI) length for the repeatedly transmitted information packets. The UE receives information packets from a base station, wherein the information packets are transmitted repeatedly by a repetition number, and wherein a RV value is selected from a preconfigured RV sequence for each repeated transmission. The UE combines received each repetition of the information packets and decoding the information packets based on the repetition configuration.

In one embodiment, the one or more RV values in the selected RV sequence are repeatedly used for the repeated transmission, by applying each RV value one by one to one block of repetitions cyclically, wherein the number of repetition in the block is determined by the repetition number and the length of the RV sequence. In another embodiment, the one or more RV values in the selected RV sequence are repeatedly used for the repeated transmission, by applying each RV value one by one to one repetition cyclically. In one embodiment, the RV value and the scrambling sequences are the same for the repetition blocks and a symbol level combination is applied.

In another one embodiment, the repetition configurations include one or more repetition parameters comprise a scrambling sequence, a RV value, a physical resource location, and a repetition type.

In one embodiment, a repeated transmission of an information packet can be implemented based on one time block in time domain. It means one repetition is performed within one time block and each repetition within one time block is self-decodable. Under such repetition mechanism, a repetition granularity in time domain is one time block. For easy description, a repetition time interval (RTI) is introduced. Under this embodiment, such repetition is based on a basic RTI with a length of one time block.

In a yet another embodiment, an information packet is repeatedly transmitted within a set of resources distributed to a plurality of time blocks, i.e., a subset of the information packet is transmitted in a subset of resources within each time block. Under this repetition mechanism, the RTI length is more than one time block and each transmission in one time block within a longer RTI is not self-decodable. Then, the receiver side can start to decode the information packet after the plurality of time blocks are received.

One of repetition mechanisms in above embodiments is an inter-repetition mechanism with a basic RTI or a longer RTI. To support one-shot transmission of an information packet within one time block and reduce delay in time domain, the information packet is repeatedly transmitted within one time block in a third embodiment. Further, such repetition also repeats within a plurality of time blocks in case that repetition within one time block cannot compensate a coverage loss. Different from the inter repetition based on one or more time blocks, there are multiple repetitions of the information packet within one time block and it can be regarded as an intra repetition mechanism. Such repetition mechanism can improve power consumption at the receiver side due to a smaller latency. Further, scheduling at network will be simpler since connected devices with a coverage loss can be served in a time-domain multiplexing scheme under such one shot transmission, considering connected devices are massive within a cell, and the size of the information packet is quite small.

DETAILED DESCRIPTION

FIG. 1is an exemplary block diagram illustrating a schematic diagram of a wireless communications system according to one embodiment of the present invention. A wireless communications system100includes one or more fixed base infrastructure units101and102, forming one or more access networks110and120distributed over a geographical region. The access network120and110may be a Universal Terrestrial Radio Access Network (UTRAN) in the WCDMA technology or an E-UTRAN in the Long Term Evolution (LTE)/LTE-A technology. The base unit may also be referred to an access point, base station, Node-B, eNode-B, or other terminologies used in the art. In some systems, one or more base stations are communicably coupled to a controller forming an access network that is communicably coupled to one or more core networks.

InFIG. 1, one or more mobile stations103and104are connected wirelessly to base stations101and102for wireless service within a serving area, for example, a cell or within a cell sector. The mobile station may also be called as user equipment (UE), a wireless communication device, terminal or some other terminologies. Mobile station103sends uplink data to base stations101via uplink channel111in the time and/or frequency domain. Mobile station104sends uplink data to base stations102via uplink channel113in the time and/or frequency domain. The serving base stations101and102transmit downlink signals via a downlink channel112and114to mobile stations103and104, respectively. In one embodiment, the communication system utilizes Orthogonal Frequency Division Multiplexing Access (OFDMA) or a multi-carrier based architecture including Adaptive Modulation and Coding (AMC) on the downlink and next generation single-carrier (SC) based FDMA architecture for uplink transmissions. SC based FDMA architectures include Interleaved FDMA (IFDMA), Localized FDMA (LFDMA), DFT-spread OFDM (DFT-SOFDM) with IFDMA or LFDMA. In OFDMA based systems, remote units are served by assigning downlink or uplink radio resources that typically comprises a set of sub-carriers over one or more OFDM symbols. Exemplary OFDMA based protocols include the developing LTE/LTE-A of the 3GPP standard and IEEE 802.16 standard. The architecture may also include the use of spreading techniques such as multi-carrier CDMA (MC-CDMA), multi-carrier direct sequence CDMA (MC-DS-CDMA), Orthogonal Frequency and Code Division Multiplexing (OFCDM) with one or two dimensional spreading, or may be based on simpler time and/or frequency division multiplexing/multiple access techniques, or a combination of these various techniques. In alternate embodiments, the communication system may utilize other cellular communication system protocols including, but not limited to, TDMA or direct sequence CDMA. The disclosure, however, is not intended to be limited to any particular wireless communication system.

InFIG. 1, wireless communication network100is an OFDM/OFDMA system comprising a base station eNB101and eNB102, and a plurality of mobile station103and mobile station104. When there is a downlink data block to be sent from base station to mobile station, each mobile station gets a downlink assignment, e.g., a set of radio resources in a physical downlink shared channel (PDSCH). When a UE needs to send an uplink data block to base station, the mobile station gets a grant from the base station that assigns a set of uplink radio resources. In 3GPP LTE system based on OFDMA downlink, the radio resource is partitioned into subframes each of which is comprised of two slots and each slot has seven OFDMA symbols in the case of normal Cyclic Prefix (CP). Each OFDMA symbol further consists of a number of OFDMA subcarriers depending on the system bandwidth. The basic unit of the radio resource grid is called Resource Element (RE), which spans an OFDMA subcarrier over one OFDMA symbol. One type of the basic block of the radio resources for scheduling in LTE is called physical resource block (PRB), each of which contains several consecutive OFDM symbols in one subframe and several consecutive subcarriers in frequency domain. Virtual resource blocks (VRB) is another type of the basic block of the radio resources definition in LTE system, which have two types: localized type and distributed type. For each virtual resource blocks, a pair of virtual resource blocks over two slots in a subframe is assigned together by a single virtual resource block number. One downlink assignment or an uplink grant consists of one or multiple basic blocks of the radio resources, e.g., a set of PRBs.

FIG. 1further shows a simplified block diagram of base station101in accordance to the current invention. Base station101has an antenna155, which transmits and receives radio signals. A RF transceiver module153, coupled with the antenna, receives RF signals from antenna155, converts them to baseband signals and sends them to processor152. RF transceiver153also converts received baseband signals from processor152, converts them to RF signals, and sends out to antenna155. Processor152processes the received baseband signals and invokes different functional modules to perform features in base station101. Memory151stores program instructions and data154to control the operations of base station101. Base station101also includes a RV handler161that handles the RV selection for the UEs.

FIG. 1also shows a simplified block diagram of mobile station103in accordance to the current invention. Mobile station103has an antenna135, which transmits and receives radio signals. An RF transceiver module133, coupled with the antenna, receives RF signals from antenna135, converts them to baseband signals and sends them to processor132. RF transceiver133also converts received baseband signals from processor132, converts them to RF signals, and sends out to antenna135. Processor132processes the received baseband signals and invokes different functional modules to perform features in mobile station103. Memory131stores program instructions and data134to control the operations of mobile station103.

Mobile station103includes several modules that carry out different tasks in accordance with embodiments of the current invention, including a repetition configurator141, a RTI estimator142, a RV selector143, and a decoder144. Repetition configurator141obtains a repetition configuration in the wireless communication system, wherein the repetition configurator configures each repetition for repeatedly transmitted information packets. RTI estimator142determines a RTI length for the repeatedly transmitted information packets. RV selector143receives information packets from a base station, wherein the information packets are transmitted repeatedly by a repetition number, and wherein a RV value is selected from a preconfigured RV sequence for each repeated transmission. Decoder144combines received each repetition of the information packets and decodes the information packets based on the repetition configuration.

Repetition Mechanism in Time Domain

In embodiments of this invention, a repeated transmission means an initial repeated transmission of an information packet, and a repeated retransmission of the information packet in case of failure decoding.

In one embodiment, a repeated transmission of an information packet can be implemented based on one time block in time domain. It means one repetition is performed within one time block and each repetition within one time block is self-decodable. Under such repetition mechanism, a repetition granularity in time domain is one time block. For easy description, such granularity is named as a repetition time interval (RTI). Moreover, such repetition scheme can be regarded as an inter-repetition mechanism based on one time block, or on a basic RTI. Subsequently, a repetition number of the transmitted information packet bits equals to a number of occupied time blocks with each carrying one repetition of the information packet. Here, a time block is a basic time unit at time domain. For example, a time block is a subframe in a LTE system.

FIG. 2shows an example of a repeated transmission of an information packet by an inter repetition mechanism based on one time block. In this figure, an information packet210is repeatedly transmitted within a duration230. Specifically, a repeated transmission of information packet210comprises a repetition220at time block200, a repetition211at time block201and a repetition213at time block202. Each repetition is different in the frequency domain.

In a second embodiment, an information packet is repeatedly transmitted within a set of resources distributed to a plurality of time blocks, i.e., a subset of the information packet is transmitted in a subset of resources within each time block. Under this repetition mechanism, the RTI length is more than one time block and each transmission in one time block within a longer RTI is not self-decodable. At the receiver side, the receiver can start to decode the information packet after the plurality of time blocks are received. This repetition scheme is an inter repetition mechanism based on a longer RTI comprising multiple time blocks. Transmissions within one longer RTI are considered as one repetition. For easy description, each transmission within one time block within the longer RTI is named as a part of one repetition.

FIG. 3shows an illustration of a repeated transmission of an information packet by an inter repetition based on a longer RTI. An information packet310comprises two information subsets311and312, and transmitted repeatedly within a duration340. Specifically, subsets311and312are repeated within different time blocks. Repetition of subset311comprises a repetition320at time block300, a repetition323at time block302, and a repetition325at time block304, while repetition of subset312comprises a repetition321at time block301, a repetition324at time block303and a repetition326at time block305. In this example, a transmission320of information subset311in time block300and a transmission321of information subset312in time block301constitute a complete repetition of the whole information packet310based on a longer RTI with two time blocks.

To support one-shot transmission of an information packet within one time block and to reduce the delay in the time domain, the information packet is repeatedly transmitted within one time block in a third embodiment. Further, such repetitions also repeat within a plurality of time blocks in case that multiple repetitions within one time block cannot compensate the coverage loss. Different from the inter repetition based on one or more time blocks, there are multiple repetitions of the information packet within one time block or a basic RTI.

Such repetition mechanism can improve power consumption at the receiver side due to a smaller latency. Further, scheduling at network will be simpler, since connected devices with a coverage loss are served in a time domain multiplexing scheme under such one shot transmission, considering connected devices are massive within a cell, and size of an information packet is quite small. To support such repetition mechanism, an indicator within a control signaling can be used to inform the receiver side in one embodiment.

FIG. 4andFIG. 5show some examples of a repeated transmission of an information packet based on the intra repetition mechanism and the inter repetition mechanism. InFIG. 4, a repeated transmission of an information packet happens within a duration440, wherein there are repetitions both within one time block and among time blocks. In this example, there are two repetitions within one time block. Within time block400, there are repetitions420and421. Moreover, there are repetitions422and423within time block401, and repetitions424and425within time block403. Such method uses both the intra repetitions and the inter repetitions for information packet410.

FIG. 5illustrates an exemplary diagram of an intra repetition within one time block. Different fromFIG. 4, there are only intra repetitions within one time block inFIG. 5. In detail, a repeated transmission of information packet510only occurs in time block501, where there are repetitions520,521,522, and523at different locations in frequency domain.

The time blocks for a repeated transmission can be contiguous in time domain in one embodiment, or discrete in time domain in another embodiment. At the receiver side, the receiver should determine which time block is occupied for a repeated transmission before reception.

Resource Allocation for a Repeated Transmission

A resource size is assumed identical for one transmission, which is one complete repetition, a part of one repetition, or multiple repetitions in each occupied time block, in this invention. However, physical resource location of each transmission in frequency domain within each occupied time block can be different. In one embodiment, physical resource locations of other transmissions in frequency domain are identical to the first physical resource location for the first transmission within the first time block, which is a starting point of a repeated transmission. In another embodiment, physical resource location within other occupied time blocks are a predefined function of a first physical resource location in a first time block. Specifically, parameters of the predefined function comprise a starting index of the first physical resource location in frequency domain, and the index of occupied time blocks for repetitions. An example function of this predefined function is as follow
Rnstart=(R1ststart+In)modNBWEq. (1)
wherein Rnstartand R1ststartdenote a start point of a physical resource location within n-th time block and 1sttime block during a repeated transmission, and NBWis a channel bandwidth. From this example, physical resource locations of other time blocks can be obtained by adding a shift based on the index of time block to the first physical resource location within the first time block.

The first physical resource location is obtained by an indicator within a control signaling in one embodiment, or predefined in another embodiment.FIG. 6andFIG. 7show illustrations of physical locations of resources within different occupied time blocks for a repeated transmission.

InFIG. 6, an information packet610is repeatedly transmitted by a repetition620in time block600, a repetition622in time block601and a repetition624in time block603. Specifically, resource locations of repetitions620,622and624are identical in frequency domain.

InFIG. 7, an information packet710is repeatedly transmitted by a repetition720in time block700, a repetition722in time block701and repetition724in time block703. Physical resource location741for repetition722is obtained by adding a shift with a value 2 to physical resource location740of repetition720, while physical resource location742of repetition724is obtained by adding a shift with value 6 to740.

Further, resources within one time block can be discrete in one embodiment and contiguous in another embodiment. Some examples are shown inFIG. 8˜FIG. 10. InFIG. 8, an information packet800is transmitted repeatedly by an inter repetition810based on one time block. Resources for one repetition820in time block850comprise two subsets830and831, and these two subsets of resources are discrete in frequency domain. InFIG. 9, an information packet900is repeatedly transmitted by an intra repetition910, and there are two repetitions within each time block. Specifically, in time block950, resources for two repetitions920and921are distributed into three subsets of resources930,931and932in frequency domain. InFIG. 10, for an intra repetition1010for an information packet1000, there are two repetitions in each time block. Specifically, resources1030in frequency domain for repetitions1020and1021in time block1050are contiguous.

Except for the resources in frequency domain, the receiver should also determine which time block to detect for reception. In one embodiment, time blocks for a repeated transmission of an information packet are discrete in time domain. In another embodiment, a set of contiguous time blocks is used for a repeated transmission.

RE Mapping/Rating Matching for a Repeated Transmission

Under an inter repetition mechanism based on a longer TTI, the length of a symbol sequence, which is generated from an information packet to be transmitted, depends on the size of overall resources within a longer RTI, wherein the overall resources comprise multiple subsets of resources with an identical size and located in occupied time blocks within a longer RTI, in one embodiment. Then, the symbol sequence is divided into multiple parts equally, wherein a length of each part depends on a size of resources within one time block, and each part is transmitted in one time block within a longer RTI.

FIG. 11shows an example of signal generation for an inter repetition based on a long RTI. In this figure, a symbol sequence1101with a length1110is generated from an information packet1100, and the symbol sequence comprises two parts1103with a length1111and1104with a length1112. One repetition of1101comprises two time blocks, i.e.,1103and1104are repeatedly transmitted within different time blocks. Specifically,1103is repeatedly transmitted by repetitions1130at time block1150,1132at time block1152and1134at time block1154, while1104is repeatedly transmitted by repetitions1131at time block1151,1133at time block1153and1135at time block1155. The length value1110of symbol sequence1101depends on the size1142of overall resource for one complete repetition within two time blocks, wherein the overall resources comprise resource1140and resource1141. Sizes of overall resources for each longer RTI (time block1150,1151,1152,1153,1154, and1155) are identical.

Under an intra repetition mechanism, a basic resource granularity is proposed for one repetition of the information packet. Specifically, a length of a symbol sequence generated from the information packet depends on a size of the basic resource granularity in one embodiment. There is one or multiple of such basic resource granularities within one time block to support one-shot transmission.

The basic resource granularity is predefined between eNB and UE, and fixed during the entire repeated transmission in one embodiment. In another embodiment, the basic resource granularity is given by a control signaling, or in some cases, the basic resource granularity is adjusted dynamically. In a third embodiment, the basic resource granularity is indicated by a higher layer signaling and changes semi-statically.

FIG. 12gives an example of signal generation for an intra repetition mechanism. In this example, an information packet1200is repeatedly transmitted by a one-shot transmission within time block1201by 4 repetitions. Specifically, a symbol sequence1201with a length1210generated from1200is repeatedly 4 times within 4 subsets of resources1220,1221,1222and1223, while the size of each subset of resource is size1230. Further, the length1210is determined by size1230. In this example,1220,1221,1222and1223are four basic resource granularities with size1230.

To support such repetition within one time block, the size of the basic resource granularity and the size of the information packet should be determined. The sizes are indicated in a control signaling, while the sizes are same for all repetitions within different occupied time blocks within one repeated transmission. Note that one size of the basic resource granularity corresponds to the size of one information packet and such relationship is specified in one embodiment, and corresponds to multiple sizes of one information packet in another embodiment.

In another embodiment, the basic resource granularity is predefined with a specific size, and several sizes of an information packet. Under this design, the sizes of the information packet are indexed and indicated by an indicator within a control signaling for transmission.

FIG. 13toFIG. 15show illustrations of designing a resource granularity under an intra repetition mechanism. InFIG. 13, a table1300about the sizes for a basic resource granularity and information packet is predefined. In the table, block1310denotes sizes for a basic resource granularity with values1311˜1315, while block1330denotes sizes for an information packet with values1331˜1334. Block1320is indices for sizes of information packet. An indicator1341within a control signaling1340will indicate a size of an information packet to the receiver side, and another indicator1342informs the receiver the size of the resource granularity.

InFIG. 14, an indicator1401within a control signaling1400carries an index value for a receiver side to determine a size of an basic resource granularity and also a size for an information packet, and the receiver can determine detail values by checking a table1420. For this example, sizes of the basic resource granularity and information packet are indexed with a one-to-one mapping relationship. Specifically, in table1420, block1440with sizes1441,1442and1443corresponds to information packet sizes1450with value1451,1452, and1453.

InFIG. 15, an indicator1501within a control signaling1500carries an index value to determine the size of the information packet. Predefined sizes for an information packet are1541,1542,1543, and indexed in a table1520by indices1531,1532, and1532. A receiver side can determine the size by an indicator1501within a control signaling. In this example, a size of a basic resource granularity is predefined.

To accommodate multiple repetitions within one time block, a reserved set of resources within one time block is predefined in one embodiment. In another embodiment, a set of resources is indicated by the control signaling. The size of overall resources for multiple repetitions within one time block is multiple of the size of the basic resource granularity.

To map symbols to available REs in case there are multiple repetitions within one time block, a symbol sequence generated from the information packet is mapped to available REs in one embodiment. Such mapping scheme can be regarded as a sequence-level mapping or a sequence-level repetition. In another embodiment, symbols within the sequence are repeatedly one by one. Different from the sequence-level repetition, such repetition can be named as a symbol-level mapping.

Some examples are given inFIG. 16andFIG. 17. InFIG. 16, a symbol sequence1610with a length L is repeatedly transmitted by repetitions1601and1602at different frequency locations within one time block, wherein each repetition occupies one pair of PRB. Here, LTE system is considered. In this example, the symbol sequence is repeatedly mapped to available resources. InFIG. 17, a symbol sequence1710with a length L is repeatedly transmitted by repetitions1701and1702at different frequency locations within one time block, wherein each repetition occupies one PRB pair, based on LTE system. In this example, symbols within1710are mapped repeatedly one by one to available resources.

The mapping scheme is specified in one embodiment. No matter which mapping scheme is applied, a repetition number within one time block depends on the size of overall resources and the size of the basic resource granularity. Alternatively, the repetition number can be expressed by the size of overall resources within one time block and a length of the symbol sequence. An example function is given as follow
Nintra=└NRE/Nsymb┘  Eq. (2)
wherein NREdenotes a resource size expressed by a number of available REs within one time block, Nsymbis a number of symbols or a sequence length.
Transmission Scheme and Reception Procedure

In a wireless communication system, a receiver side, either a terminal or a base station, need to combine received data for decoding under HARQ retransmission, wherein a same redundancy version (RV) or different RVs will be used for retransmissions, compared to an initial transmission of a data packet or a sequence of information bits. Taking LTE system as an example, RV value for downlink transmission is indicated by the control signaling, carried by PDCCH. Alternatively, RV value can be predefined for uplink transmission.

To support a repeated transmission of an information packet, a RV sequence is repeatedly used for symbol generation in one embodiment, wherein elements within the RV sequence are different from each other, or some elements within the RV sequence share the same value. If all elements within the RV sequence are identical, only one RV value is used for repetitions actually, i.e., RV values for all repetitions are identical.

For a repeated retransmission of the information packet, a second RV sequence different from a first RV sequence for an initial repeated transmission can be used. Each RV sequence for each retransmission can be different or identical. The length of the RV sequence is less than or equal to the repetition number. The RV sequence is used repeatedly. If the length of the RV sequence is equal to one, it means only one RV is used for all repetitions within a repeated transmission or retransmission. One RV value can be used to multiple consecutive repetitions (for example, X repetitions), and all RV values within the sequence are cycled by each X repetitions.

In one novel aspect, a RV sequence is selected from a predefined set of RV sequences for the repeated transmission. In one embodiment, the RV sequence with one or more RV values are repeatedly used for the repeated transmission, by applying each RV value one by one to one block of repetitions cyclically. In one embodiment, each scrambling sequence is the same for its corresponding RV value in the RV sequence for the repetition transmission. As such, at the receiver side, the symbol-level can be used before demodulation. In another embodiment, the RV sequence with one or more RV values is repeatedly used for the repeated transmission, by applying each RV value one by one to one repetition cyclically.FIG. 18andFIG. 19show some examples of a repeated transmission with a predefined RV sequence.

InFIG. 18, a RV sequence1840with a length1820comprising RV elements1841,1842,1843, and1844is repeatedly used for a repeated transmission1810. Specifically, different symbol sequences are generated by different RV values. RV element1841is used for a repetition1810at time block1800; RV element1841is used for a repetition1811at time block1801; RV element1843is used for repetitions1812and1814at time blocks1802and1805; RV element1844is used for repetitions1813and1815at time blocks1803and1806. In this example, a repetition number of the repeated transmission1890is a multiple of the RV sequence length1820.

In embodiment, the RV sequence is repeatedly used for the repeated transmission by applying each RV value one by one to one repetition cyclically. The RV sequence1840with length1820comprising RV elements1841,1842,1843, and1844is repeatedly used for a repeated transmission1820. Specifically, different symbol sequences are generated by different RV values. For example, repetition transmission1820uses RV sequence1840by applying the RV value of1840one to one repetition cyclically. The RV values,1841,1842,1843, and1844applies to each repetition one by one cyclically. RV element1841is used for a repetition1821at time block1891; RV element1842is used for a repetition1822at time block1892; RV element1843is used for repetition block1823and1893. RV element1844is used for repetition block1824at1894. After the end of the RV sequence, the RV sequence is cyclically applied to the rest of repetition blocks. RV element1841is used for a repetition1825at time block1895; RV element1842is used for a repetition1826at time block1896; RV element1843is used for repetition block1827and1897. RV element1844is used for repetition block1828at1898.

In another embodiment, the RV sequence is repeatedly used for the repeated transmission by applying each RV value one by one to one block of repetitions cyclically, wherein the number of repetition in the block is determined by the repetition number and the length of the RV sequence. Specifically, each RV value is repeated used for a block of repetition cyclically. Specifically, different symbol sequences are generated by different RV values. For example, repetition transmission1830uses RV sequence1840by applying the RV value of1840one to one block of repetition cyclically. The number of repetition in the block is determined by the repetition number and the length of the RV sequence. In this example, the number of repetition is eight and the length of the RV sequence is four. Therefore, there are two blocks of repetition apply the same RV value. RV element1841is used for a repetition1831and1832at time block1891and1892. RV element1842is used for a repetition1833and1834at time block1893and1894. RV element1843is used for a repetition1835and1836at time block1895and1896. RV element1844is used for a repetition1837and1838at time block1897and1898.

InFIG. 19, a RV sequence1940with a length1920comprising RV elements1941,1942,1943, and1944is repeatedly used for a repeated transmission1990. Specifically, different symbol sequences are generated by different RV values. RV element1941is used for a repetition1910and1914at time block1900and1904; RV element1941is used for a repetition1911at time block1901; RV element1943is used for repetitions1912and1915at time blocks1902and1906; RV element1944is used for repetitions1913at time blocks1903. In this example, a repetition number of the repeated transmission is not a multiple of RV sequence length1920, and RV element1943is used for the last repetition1915.

Under an inter repetition mechanism based on a basic RTI or a longer RTI, only one RV is used for one repetition within the basic RTI or the longer RTI. Under an intra repetition mechanism, one RV is used for multiple repetitions within one time block in one embodiment. In another embodiment, a RV sequence is used repeatedly for the whole repetition, and different RV values are applied for different repetitions within one time block.

FIG. 20andFIG. 21show examples of an intra repetition with a RV sequence. InFIG. 20, a RV sequence2030with a length2020is used for a repeated transmission2060, wherein2060is based on an inter repetition and an intra repetition. Moreover, RV sequence2030comprises multiple RV elements2040,2041,2042and2043, and these RV elements are used for different repetitions. In this example, the whole RV sequence is used repeatedly by applying different RV values for different repetitions within one time block. RV element2040is used a repetition2010at time block2000, and RV element2041is used for another repetition2011within the same time block; RV element2042is used for a repetition2012at time block2001, and repetition2015at time block2002, and RV element2043is used for another repetition2013within the same time block2001, and repetition2014at time block2002. Last two repetitions2014and2015within time block2002are based on RV element2043and2042respectively, since repetition number of2060is multiple of2020.

InFIG. 21, a RV sequence2130with a length2120is repeatedly used for a repetition2160. Specifically, a RV element2140is used for repetitions2110and2111within time block2100; a RV element2141is used for repetitions2112and2113at time block2101; a RV element2143is used for repetitions2114and2115within time block2102. Note that the number of occupied time blocks for2160is multiple of2120, and the last RV element2143within2130is used for repetitions within the last occupied time block2102of2160.

If each RV value for each repetition is identical, and each scrambling sequence for each repetition is identical. A repeated transmission means a same symbol sequence is repeatedly transmitted in one embodiment. It can be regarded as an identical repetition. To generate a scrambling sequence for all repetitions, the scrambling sequence can be a function of a first time block index, wherein the first time block is a starting point for a repeated transmission or retransmission. In another embodiment, different symbol sequences, which are generated from the same information packets are transmitted in different repetitions. Here, different symbol sequences means different RV values are applied to explore a coding gain, or different scrambling sequences are used to randomize interference. It is assumed that a modulation order remains identical during repetitions for above designs.

To determine a RV sequence, a set of RV sequences is predefined and an indicator within a control signaling informs the receiver side about the used RV sequence implicitly in on embodiment. At the receiver side, the receiver can determine the used RV sequence by checking a RV sequence index carried by the indicator. In another embodiment, a predefined rule is specified to get RV values for each repetition without any signaling.

Before to receive a repeated transmission of an information packet, at the receiver side, the receiver should first determine configurations for each repetition, wherein the configurations comprise scrambling sequence, RV value, and physical resources including locations in time domain and frequency domain, repetition mechanism (inter repetition or intra repetition). If an identical repetition is applied, the receiver can combine received symbols from different repetitions directly in one embodiment, i.e., a symbol-level combination is performed. The receiver can combine outputs after demodulation in another embodiment. If an identical repetition is not applied, the receiver should perform a combination after demodulation, i.e., a bit-level combination is performed, in a third embodiment.

A reception procedure at the receiver side in one embodiment can be described as followStep 1: determining configurations for each repetition based on control signaling or some predefined rules, like physical resource, scrambling sequence, RV sequence, etc.Step 2: receiving repetitions one by one at corresponding frequency-time resources.Step 3: determining whether it is possible to perform a symbol-level combination among repetitions?If yes, performing a symbol-level combination among received repetitions (Step 4), and then go to Step 6.If not, demodulating received data and obtaining a combination output by combining each demodulation output of each repetition (Step 5), and then go to Step 7.Step 6: demodulating received symbols, and then go to step 7.Step 7: decoding received symbols based on output in Step 5 or Step 6, and end the procedure.

In another embodiment, a reception procedure at the receiver side in one embodiment can be described as followStep 1: determining configurations for each repetition based on control signaling or some predefined rules, like physical resource, scrambling sequence, RV sequence, etc.Step 2: receiving repetitions one by one at corresponding frequency-time resources.Step 3: demodulating each received repetitionStep 4: combining each demodulation output of each received repetition.Step 5: decoding received data based on a combination output in Step 4.

Note that at the receiver side, the receiver can perform decoding by receiving some repetitions, without receiving all repetitions, to reduce time delay in a realistic system in one embodiment. If a successful decoding achieved, for example, CRC check is passed, the receiver can determine a successful reception of transmitted data, and can stop to receive rest repetitions.

FIG. 22andFIG. 23illustrate examples of a procedure of decoding an information packet under a repeated transmission. InFIG. 22, at the receiver side, the receiver determines configurations for each repetition within a repeated transmission in Step2200before performing reception, and then starts to receive each repetition (Step2210). If yes, go to a determination that an identical repetition is applied for the repeated transmission in Step2220, the received will combine received repetitions by a symbol-level combination (Step2230). Then, the receiver will judge whether the repetition finishes (Step2230). If not to Step2230, the receiver will continue to receive rest repetitions. If yes to Step2230, a demodulation will be performed based on the symbol-level combination output (Step2231). Further, received data will be decoded (step2240) by inputting the demodulation output in Step2231. If no to Step2220, the receiver will demodulate each received repetition and buffer each demodulation output (Step2222). Then, the receiver will judge whether the repetition finishes (Step2250). If not to Step2250, the receiver will continue to receive rest repetitions. If yes to Step2250, an output will be obtained for data decoding (Step2240) by combining each demodulation output of each repetition (Step2260).

InFIG. 23, before receiving each repetition (Step2310), at the receiver side, the receiver determines configurations for each repetition within a repeated transmission firstly (Step2300). After receiving one repetition, a demodulation of the received repetition is performed and each output is buffered (Step2320). Then, the receiver will determine whether all repetitions are received (Step2330). If yes to Step2330, a decoding will be performed (Step2350) by combining each demodulation output (Step2340) and the whole procedure stops. If not to Step2330, the receiver continues to receive repetitions.

FIG. 24illustrates an exemplary flow chart of the repetition design using predefined RV sequences in accordance with embodiments of the current invention. At step2401, the UE obtains a repetition configuration in a wireless communication system, wherein the repetition configuration configures each repetition for repeatedly transmitted information packets. At step2402, the UE determines a RTI length for the repeatedly transmitted information packets. At step2403, the UE receives information packets from a base station, wherein the information packets are transmitted repeatedly by a repetition number, and wherein a RV value is selected from a preconfigured RV sequence for each repeated transmission. At step2404, the UE combines received each repetition of the information packets and decoding the information packets based on the repetition configuration.