WO2018027917A1

WO2018027917A1 - Methods and apparatus for uplink data transmission

Info

Publication number: WO2018027917A1
Application number: PCT/CN2016/094911
Authority: WO
Inventors: Feifei SUN
Original assignee: Mediatek Singapore Pte. Ltd
Priority date: 2016-08-12
Filing date: 2016-08-12
Publication date: 2018-02-15
Also published as: WO2018028604A1; CN108605364A; TW201806422A

Abstract

Methods and apparatus for UL transmission are provided. In one novel aspect, a method for UL transmission comprises: UE transmits a contention-based resource reservation request (RRR) to eNB. eNB sends a response signal, e. g. an authorization on a reservation resource related to the resource reservation request. UE sends UL data transmission on the reserved resource to eNB. UE could perform retransmission after the first UL data transmission. Optional, eNB feedbacks a ACK/NACK after UE transmits/retransmits UL data. In another novel aspect, firstly, UE transmits request with UL date in the reservation resource to eNB, and then eNB feeds back ACK/NACK to UE, and UE performs UL retransmission based on the ACK/NACK. In another novel aspect, the reservation resource is 1-to-1 mapping the resource for ACK/NACK.

Description

METHODS AND APPARATUS FOR UPLINK DATA TRANSMISSION

FIELD OF INVENTION

This disclosure relates generally to wireless communications and, more particularly, to uplink transmission of UEs.

BACKGROUND OF THE INVENTION

Machine-Type Communication (MTC) is an important revenue stream for operators and has a huge potential from the operator perspective. Lowering the cost of MTC user equipment (UEs) /devices is an important enabler for the implementation of the concept of "Internet of Things" (IOT) . Many MTC devices are targeting low-end (low average revenue per user, low data rate) applications that can be handled adequately by GSM/GPRS. Owing to the low-cost of these devices and good coverage of GSM/GPRS, there is very little motivation for MTC UE suppliers to use modules supporting the LTE radio interface. In order to ensure that there is a clear business benefit to MTC UE vendors and operators for migrating low-end MTC devices from GSM/GPRS to LTE networks, a new type of terminal, i.e. a low cost (LC) MTC UE, is introduced in Rel-11. The cost of the LC-MTC UEs is tailored for the low-end of the MTC market to be competitive with that of GSM/GPRS terminals. The LC-MTC UEs are characterized by: 1) One Rx antenna； 2) Downlink and uplink maximum TBS size of 1000 bits； 3) Bandwidth reduction (BR) –resources for each channel transmission are limited to contiguous 6 PRBs (1.4MHz) for cost reduction, and 4) Coverage enhancement –some applications of LC-MTC UEs will require 15-20dB coverage extension and repeated transmission is a common technique to compensate penetration losses.

In LTE Rel. 12, it is shown that the implementation of half-duplex FDD (HD-FDD) MTC with single received antenna is cost-competitive. The bandwidth reduction technique can offer further cost reduction. The UE with bandwidth reduction (BR-UE) can be implemented with lower cost by reducing the buffer size, clock rate for signal processing, and so on. In IoT/MTC traffic, there is a lot of infrequent small UL traffic data, e.g., up to 100～200 bytes uplink traffic periodically reported 1/hour to 1/year.

Targeting the above scenario, reuse current cellular uplink data transmission, which requires e.g., RACH, establishing a RRC connection, is not efficient. The signaling overhead is quite large: hundreds of bytes information exchanges before the RRC setup.

Novel UL transmission methods are needed to make the BR-UE be able to be signaling and resource efficient.

SUMMARY OF THE INVENTION

Methods, UE and eNB to transmit uplink transmission for wireless communication are provided.

In a first novel aspect, a method is provided, comprising: transmitting a reservation resource request to eNB by a UE in wireless system； receiving ACK/NACk from the eNB； and transmitting UL data a reservation resource to the eNB.

In one embodiment, the reservation resource is indicated explicitly or implicitly to the UE by the eNB by broadcasting or RRC signaling.

In another embodiment, the reservation resource is with a predetermined hopping pattern.

In yet another embodiment, wherein the resource for ACK/NACk is associated with the reservation resource. And multiple ACK/NACk for multiple UEs are localized or distributed.

In another novel aspect, another method is provided, comprising: transmitting a request with UL message to eNB by a UE in wireless system； receiving ACK/NACk from the eNB； and retransmitting UL data a reservation resource to the eNB.

In one embodiment, wherein the NACK indicates to the UE, the UL message does not successfully decoded.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the embodiments, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings.

FIG. 1 illustrates a wireless communication system in accordance with some embodiments of current invention.

Fig. 2 illustrates a method flow of Contention based UL resource reservation in accordance with some embodiments of current invention.

Fig. 3 illustrates another method flow of Contention based UL resource reservation in accordance with some embodiments of current invention.

Fig. 4 illustrates another method flow of Contention based UL resource reservation in accordance with some embodiments of current invention.

Fig. 5 illustrates frequency hopping pattern for different UEs in accordance with some embodiments of current invention. In this embodiment.

Fig. 6 illustrates the resource allocation for RRR, response signal and reservation resources according to the embodiments of this invention

Fig. 7 illustrates the resource allocation for RRR, response signal and reservation resources according to the embodiments of this invention.

Fig. 8 illustrates the mapping between the reservation resources and the resource for response signal according to the embodiments of this invention.

Fig. 9 illustrates the mapping between the reservation resources and the resource for response signal according to the embodiments of this invention.

Fig. 10 illustrates the mapping between the reservation resources and the resource for response signal according to the embodiments of this invention.

Fig. 11 further illustrates power control for UL non-orthogonal multiple access (NOMA) according to the embodiments of this invention.

Corresponding numerals and symbols in the different figures generally refer to corresponding parts unless otherwise indicated. The figures are drawn to clearly illustrate the relevant aspects of the embodiments and are not necessarily drawn to scale.

DETAILED DESCRIPTION

Certain terms are used throughout the description and following claims to refer to particular components. As one skilled in the art will appreciate, manufacturers may refer to a component by different names. This document does not intend to distinguish between components that differ in name but not function. In the following description and in the claims, the terms "include" and "comprise" are used in an open-ended fashion, and thus should be interpreted to mean "include, but not limited to ... " . Also, the term "couple" is intended to mean either an indirect or direct electrical connection. Accordingly, if one device is coupled to another device, that connection may be through a direct electrical connection, or through an indirect electrical connection via other devices and connections. The making and using of the embodiments of the disclosure are discussed in detail below. It should be appreciated, however, that the embodiments can be embodied in a wide variety of specific contexts. The specific embodiments discussed are merely illustrative, and do not limit the scope of the disclosure. Some variations of the embodiments are described. Throughout the various views and illustrative embodiments, like reference numbers are used to designate like elements.

In IoT/MTC traffic, there is a lot of infrequent small UL traffic data, e.g., up to 100～200 bytes uplink traffic periodically reported 1/hour to 1/year. Targeting the above scenario, reuse current cellular uplink data transmission, which requires e.g., RACH, establishing a RRC connection, is not efficient. The signaling overhead is quite large: hundreds of bytes information exchanges before the RRC setup. In addition, in order to achieve UL coverage, narrow band system/signal carrier system provides a very promising coverage without increasing UL Tx power. Multiple tones/resources are available for UE to do accessing. Furthermore, with longer CP and GP, TA is not needed before data transmission.

Contention based uplink transmission can significantly reduce signaling overhead. However, there are some issues to be solved. For example, for the poor coverage of UE, UE may need to transmit for a long time to compensate path loss, it is too costly on power consumption if a long transmission collides with another UE’s transmission, so that it has to retransmit data. On the other hand, it is hard to support HARQ combination if the transmission is contention based than scheduling based.

Methods to provide a more efficiency contention based UL transmission including contention based UL resource reservation, power control for NOMA (non-orthogonal multiple access) are provided. In addition, methods of HARQ for UL contention based UL transmission, which will allow eNB to obtain HARQ combining gain to improve the performance, are provided.

FIG. 1 illustrates a wireless communication system in accordance with some embodiments. The wireless communication system 100 includes one or more fixed base infrastructure units forming a network distribution over a geographical region. The base unit may also be referred to as an access point, access terminal, base station, Node-B, eNode-B (eNB) , or by other terminology used in the art. As shown in FIG. 1, the base units,

e.g. eNB

101 and 102 serve a number of remote units, e.g. UE 103 and 110 within a serving area, for example, a cell, or within a cell sector. In some systems, one or more base units are communicably coupled to a controller to form an access network that is communicably coupled to one or more core networks. The disclosure however is not intended to be limited to any particular wireless communication system.

In some embodiments, UE 103 or 110 comprises a wireless module (not shown in FIG. 1) for performing the functionality of wireless transmissions and receptions to and from

eNB

101 and 102, and comprises a controller module (not shown in FIG. 1) for controlling the operation of the wireless module and other functional components, such as a display unit and/or keypad serving as the MMI (man-machine interface) , a storage unit storing the program codes of applications or communication protocols, or others. To further clarify, the wireless module may be a radio frequency (RF) unit, and the controller module may be a general-purpose processor or a micro-control unit (MCU) of a baseband unit.

Generally, the

eNB

101 and 102 respectively transmit downlink communication signals 112, 113 to UE 103, and 104 in the time and/or frequency and/or code domain. UE 103, and 104 communicate with one or more eNB 101 and 102 via uplink communication signals 113, and 114 respectively. The one or more eNB 101 and 102 may comprise one or more transmitters and one or more receivers that serve the

UE

103 and 103. The UE 103, and 104 may be fixed or mobile user terminals. The UE may also be referred to as subscriber units, mobile stations, users, terminals, subscriber stations, user terminals, or by other terminology used in the art. The UE 103, and 104 may also comprise one or more transmitters and one or more receivers. The UE 103, and 104 may have half-duplex (HD) or full-duplex (FD) transceivers. Half-duplex transceivers do not transmit and receive simultaneously whereas full-duplex terminals transmit and receive simultaneously. In one embodiment, one eNB 101 can serve different kind of UEs. UE 103 and 104 may belong to different categories, such as having different RF bandwidth or different subcarrier spacing. UE belonging to different categories may be designed for different use cases or scenarios. For example, some use case such as Machine Type Communication (MTC) may require very low throughput, delay torrent, the traffic packet size may be very small (e.g., 1000 bit per message) , extension coverage. Some other use case, e.g. intelligent transportation system, may be very strict with latency, e.g. orders of 1ms of end to end latency. Different UE categories may be introduced for these diverse requirements. Different frame structures or system parameters may also be used in order to achieve some special requirement. For example, different UEs may have different RF bandwidths, subcarrier spacings, omitting some system functionalities (e.g., random access, CSI feedback) , or use physical channels/signals for the same functionality (e.g., different reference signals) .

FIG. 1 also shows an exemplary diagram of protocol stacks for control-plane for UE 103 and eNB 101. UE 103 has a protocol stack 121, which includes the physical (PHY) layer, the medium access control (MAC) layer, the radio link control (RLC) layer, the pack data convergence protocol (PDCP) layer, and the radio resource control (RRC) layer. Similarly, base station eNB 101 has a protocol stack 122, which includes the PHY layer, the MAC layer, the RLC layer, the PDCP layer, and the RRC layer, each of which connects with their corresponding protocol stack of UE protocol stack 121.

Figure 1 also includes a simplified block diagram of UE and eNB in accordance with novel aspects of the current invention, wherein, the UE could be UE 103, and the eNB could be eNB 101. UE comprises memory 131, a processor 132, a transceiver 133 coupled to an antenna 135. UE also comprises various function modules including ACK/NACK processing module 142, for processing ACK/NACK information； and resource management module 141, for processing the resources for transmission/retransmission. And the above function module could be implemented by software, hardware , firmware of the combination of the above.

The eNB 101 comprises memory 151, a processor 152, a transceiver 153 coupled to an antenna 155. eNB also comprises various function modules including ACK/NACK processing module 156, for processing ACK/NACK information； and resource management module 157, for processing the resources for transmission/retransmission from UEs, decoding module 158, for decoding UL message from UEs. The above apparatus may be implemented with a bus architecture. The bus may include any number of interconnecting buses and bridges depending on the specific application of the system structure and the overall design constraints. The bus links together various circuits including one or more processors and/or hardware modules, represented by the processor and different modules and the computer-readable medium. The bus may also link various other circuits such as timing sources, peripherals, voltage regulators, and power management circuits, which are well known in the art, and therefore, will not be described any further. It is understood that the specific order or hierarchy of steps in the processes disclosed is an illustration of exemplary approaches. Based upon design preferences, it is understood that the specific order or hierarchy of steps in the processes may be rearranged. Further, some steps may be combined or omitted. The accompanying method claims present elements of the various steps in a sample order, and are not meant to be limited to the specific order or hierarchy presented.

In one embodiment, the wireless communication system 100 utilizes an 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) , and DFT-spread OFDM (DFT-SOFDM) with IFDMA or LFDMA. In OFDMA based systems, UE 103 and 110 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 Long Term Evolution (LTE) of the 3GPP UMTS standard and the 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. In other embodiments, the architecture 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 wireless communication system 100 may utilize other cellular communication system protocols including, but not limited to, TDMA or direct sequence CDMA.

For example, in the 3GPP LTE system based on SC-FDMA uplink, the radio resource is partitioned into subframes, and each of the subframes comprises 2 slots and each slot has 7 SC-FDMA symbols in the case of normal Cyclic Prefix (CP) . For each user, each SC-FDMA symbol further comprises a number of subcarriers depending on the uplink assignment. The basic unit of the radio resource grid is called Resource Element (RE) which spans an SC-FDMA subcarrier over one SC-FDMA symbol.

Each UE gets an assignment, i.e., a set of REs in a Physical Uplink Shared Channel (PUSCH) , when an uplink packet is sent from a UE to an eNB. The UE gets the downlink and uplink assignment information and other control information from its Physical Downlink Control Channel (PDCCH) or Enhanced Physical Downlink Control Channel (EPDCCH) whose content is dedicated to that UE. The uplink assignment is indicated in downlink control information (DCI) in PDCCH/EPDCCH. Usually, the uplink assignment indicated the resource allocation within one certain subframe, for example k+4 subframe if DCI is received in subframe k for FDD and for TDD, the timing relationship is given in a table in TS 36.213. TTI bundling is used in uplink transmission in LTE system to improve uplink coverage. If TTI bundle is enabled, one uplink assignment indicates several subframes to transmit one transport block using different redundancy version (RV) .

Uplink control information is transmitted in Physical Uplink Control Channel (PUCCH) or transmitted with or without a transport block in PUSCH. UCI includes HARQ, scheduling request (SR) , channel status information (CSI) . PUCCH is allocated the border PRBs in uplink system bandwidth. Frequency diversity gain for PUCCH is obtained by frequency hopping between two slots in one subframe. Code Division Multiplexing (CDM) is used for PUCCH multiplexing between different UEs on the same radio resource.

Fig. 2 illustrates a method flow of Contention based UL resource reservation in accordance with some embodiments of current invention. Please refer to fig. 2, UE is in connected mode or in idle mode, in step 1, UE 201 transmits a contention-based resource reservation request (RRR) to eNB 202. And in step 2, eNB 202 sends a response signal, e.g. an authorization on a reservation resource related to the resource reservation request from UE to UE 201. In step 3, UE 201 sends UL data transmission on the reserved resource to eNB 202. In one case, UE 201 could perform retransmission after the first UL data transmission. Optional, eNB 202 feedbacks an ACK/NACK signal after UE transmits/retransmits UL data. After that, if UE 201 received NACK, UE 201 could perform retransmission until eNB 202 sends back ACK, end the procedure. If UE 201 does not received ACK under some condition, for example, a retransmission timer expires, or the maximum retransmission reached, UE 201 turns into IDLE mode if UE 201 is in connected mode originally, or UE 201 keeps in IDLE mode if UE is in IDLE mode originally.

Please further refer to fig. 2, before Step 1, UE selects a resource within resource pool to send a UL message. This UL message, in one embodiment, it could be a “reservation resource request” message. In another embodiment, it includes UE ID within the RRR, and in another embodiment, it comprises a UL transmission block, which may carry UL traffic data, or called UL message.

In the first example, the “resource reservation request (RRR) ” may be a sequence. And eNB 202 can detect the RRR with low complexity. UE 201 can send RRR within a short time, avoiding to send a large message, when eNB cannot decode it due to bad channel condition or if collides with other UEs. It is good for UE to save power consumption by avoiding useless transmission.

Please refer to fig. 2, in Step 2: UE receives a response signal from eNB. This response signal could be authorization signal. Alternatively, this response signal could be an ACK/NACK signal. And in details, UE receives the response signal on a resource could base on transmission of RRR message: RRR content based (hereinafter, CR) , or RRR resource based (herein after, RR) ； and reception of response signal authorization signal (AR) , or resource of authorization signals (SR) . The eNB replies response signal based on AR or SR of RRR. In one example, this authorization signal (a) and the resource (b) transmitting the response signal is 1-on -1 mapping to the resources used in “resource reservation request” message. According to the different formats of response signals, the following embodiment are described :

In case 1, the response signal is based on CR +AR, in this case, UE transmits sequence n for Resource Reservation Request (RRR) , eNB generates a response signal based on sequence n. Or UE transmits RRR with one message (e.g., UE ID, RNTI, Random number) , eNB generates a response signal based on the one message (e.g., UE ID, RNTI, Random number) .

In case 2, the response signal (AR) is based on the resource of RRR (RR) ., In this case, authorization signal is generated by eNB based on the resource of RRR, where the resource of RRR is one or combination of more: time/frequency resource (one subcarrier is a special case. ) , spreading code, scrambling code, code book. For example, UE selects the resource_n for RRR； on the resource n , UE transmits RRR message, ； eNB generates a response signal based on the resource n, for example, based on the index, indicator or location of the resource, wherein the resource n could be one or combination of more: time/frequency resource (one subcarrier is a special case) , spreading code, scrambling code, or code book.

For the above two cases, the response signal is transmitted in a pre-known resource (or UE blind detected in a resource set) , e.g., pre-defined resource, or can be determined based the resource (e.g., FH pattern) used in step 1 (one on one mapping to the resource used by UE) . Some one-to-one mapping can be defined to avoid blind detection in UE to save power consumption. For example, , in some RS_MAP field in MAC header.

In case 3, the response signal is based on RR+SR, in this case, UE selects the resource n for RRR transmission, where the resource n is one or multiple of time/frequency resource, spreading code, code book, scrambling code, sequence, subcarrier index, etc； eNB transmit a response signal on resource m, where resource m is selected by eNB based on resource n. In another word, UE transmits RRR message on selected resource n； UE detects for response signal on resource m corresponding to resource n for RRR message transmission.

In case 4, the response signal is based on CR+SR, in this case, UE transmits RRR with a content (e.g., UE ID, RNTI, Random number) ； eNB transmit a response signal on resource m based on the content in RRR. For example, UE transmits RRR message with C-RNTI and eNB successfully decodes the RRR message, obtains the content C-RNTI, and transmits a response signal on resource m, where resource m is based on the content C-RNTI. In this example, UE detects for the response signal on resource m based on its C-RNTI..

In the above cases, the response signal, for example the authorization signal may include UE identity (UE ID or RNTI) , which is similar as current Msg 4 for contention resolution.

Please refer to fig. 2. In step 3, in option 1, If UE successfully decodes an authorization signal, UE transmits UL data in the corresponding resources to the “RRR” . UE may attempt to decode the authorization signal within a window. (As UE expecting Msg 2. ) As mentioned above in step 2, RS_MAP field in MAC header may be used. In option 2, If UE does not decode an authorization signal (e.g., no indication in RS_MAP) , UE assumes it failed. UE will select a new reservation resource and send RRR again, which is similar to the way UE expecting Msg 2. If UE does not receive ACK or NACK signal, UE may wait for a random time, or wait for a while based on the configuration in SIB from eNB for a while before transmitting the next request.

In one novel aspect, more than one UE may send same or different RRR on the same resource. eNB may be able to know it or not. If eNB knows it, eNB can tell UE NACK, or simply sends nothing so that UE will re-transmit RRR later. If eNB doesn’t know it, the collision may happen in step 3 of fig. 2, then contention resolution is needed later. The difference between the proposed method and legacy PRACH is, in Msg 2, there is no need to transmit that much bit (e.g., UL grant, TA, RNTI) , 1 bit granted message is enough.

Fig. 3 illustrates another method flow of Contention based UL resource reservation in accordance with some embodiments of current invention. Different from fig. 2, in step 1 of fig. 6, the RRR includes at least UE ID. And UE ID could be UE ID/RNTI/random number, BSR, CSI, or data volume (DV) . And in step 2, similar as message 2, eNB sends UL grant with UE ID for contention resolution on the resource used for response signal. And in step 3, UE performs UL data transmission on the reservation resource. If eNB receives and decodes the UL data, and eNB transmits ACK to UE in step 4, or transmits NACK to UE in step 4 if eNB does not successfully decoding the information from UE. And then, UE could perform retransmission until ACK. And then UE turns in to IDLE mode or PSM mode for power saving. Please note that, after receiving NACK, SPS-liked scheme can be used by UE so that multiple TBs can be transmitted.

In this embodiment, the “resource reservation request” includes an identity (e.g., UE ID (40bits) , or RNTI (16bits) , or a random ID selected by UE) , where the UE identity is used for eNB 202 to know which UE is sending message. Please refer to table. 1. For example in the second example, in NB-IoT system, Msg 3 is 88 bits, including: resume ID, Est Cause, short MAC-I, DCI (mac) , MAC spare, PHR, MAC overhead, RRC overhead, RRC spare. DVI is the data volume in MSG3 indicates the amount of user data (including SMS) and NAS signalling data volume sent over user plane or control plane. The DVI field is in MAC. And the 88bits of message 3 is the only TB size that is assumed, when specifying support for UL CCCH. In this example, the multi-tone capability bit should be interpreted as an IOT bit (inter operability test) .

Table. 1 Msg 3 content in NB-IoT

For the embodiments of fig. 2 and fig. 3, similar to procedure for PRACH, the RRR, or called the scheduling request can be on part of the reserved resource for PRACH. So that eNB can know this is different from PRACH and gives a larger UL grant than the ordinary UL grant for PRACH in step 2 of fig. 2 or fig. 3, which grants transmission for step 3. For eNB, it will consider the BSR or DV report in scheduling request for transport block size in UL grant, and further, it will consider the CSI in the scheduling request for MCS in UL grant. Especially in NB-IoT system, the reserved bit in Msg 2 can be used for UL grant of Msg 3, for UE to choose the reserved part of resource of PRACH to read the reserved resource.

Fig. 4 illustrates another method flow of Contention based UL resource reservation in accordance with some embodiments of current invention. In this embodiment, UE can transmit UL message with the resource reservation without any request, and on this reservation resource, UE can transmit more than one transport block on the reserved resource one time or several times in step 1. Further to say, UE can send a resource release message in the UL message in step 1.

Because UE transmitted the UL messages within or as the RRR, so eNB could receive the UL message from UE on the reservation resource in step 1, and after decoding the UL message on the reserved resource, eNB expects one or more UL transmission on a corresponding UL data transmission resource. There is no need to for explicit UL grant, and may be contention free. Furthermore, in step 2, eNB may transmit an ACK or NACK signal to UE to trigger a retransmission or new transmission.

In one embodiment, the UL message can include a sequence. The sequence can further used by eNB for channel estimation, or for eNB to detect for if there is any UE sending request. Moreover, eNB can detects this sequence to know if there is more than one UE request to use this resource. In one case, eNB sends ACK/NACK signal, eNB may be able to detect for a sequence on a UL resource, but fails to decode a UL message. eNB can send an NACK signal to trigger an retransmission of the UL message. The UL message further includes: FH pattern (frequency resource allocation in each subframe) , and/or start subframe, and/or end subframe, number of repetition, scrambling sequence, code book index, spreading code.

The end subframe may be learned by eNB by receiving an “end transmission indicator” . By this way, eNB learns that UL data transmission resource from the UE transmitting with resource reservation request are released. The end subframe is not necessary if a field indicated how many packets need to be transmitted is signaled by UE in step 1.

The reservation resources could be localized or distributed with FH or not. And the distributed resource could be called separated resource. And the pros of separated resource: there is no need for contention expected during the UL data transmission from other UE. And the relationship between the reservation resource and the resource for response signal is the same with the above embodiment, for example, there is binding relationship between the reservation resource and the resource for response signal, for example, one-to-one mapping.

Please note that, although the embodiment of fig. 4 is described without additional RRR, the embodiment of fig. 4 could be combined with embodiments in fig. 2 and fig. 3, as the step 4, which comprising the transmission/retransmission with ACK/NACK.

Fig. 5 illustrates frequency hopping pattern for different UEs in accordance with some embodiments of current invention. In this embodiment. For the reservation resources used in embodiments of fig. 2-fig4, the reservation resources belong to a resource pool. The “resource pool” is pre-known to UE 201, for example, by broadcasting in the system information, indicating by SIB information or other RRC message to UE 201. And the “resource pool” may be related to cell ID, UE ID, subframe number, frame number, so the “resource pool” could be indicated to UE 201 explicitly or implicitly.

The “resource pool” further includes several sub-pools for different coverage class/level, or channel status class/level, the division of sub-pools could be based on RSRP. The “resource pool” may comprise one or multiple of: time/frequency resource (one subcarrier is a special case) , spreading code, scrambling code, code book. And in further embodiment, the “resource pool” may be based on frequency hopping, and different sub-pools contain be based on different FH patterns, or different frequency allocation. Based on the different requirements, different UEs could choose different reservation resources from the resource pool. Meanwhile, eNB can configure one or more RSRP threshold for UE to select resource from different sub-pools. Note: Multiple UE select in the resource pool, therefore the message is contention based. In one special case, the response signal could be transmitted in the RS_MAP field of MAC header.

Because the relationship between the reservation resource and the resource used for response signal is associated, so the overhead for decoding of UE or transmitting for eNB is low. In a first aspect, it is an Easy way for eNB to detect this RRR since it may be only a sequence as PRACH, in the second aspect, if no RRR received by eNB, corresponding “the resource used for the response signal ” associated with the RRR, can be scheduled by eNB to other UEs for scheduling based UL transmission. This can improve the utilization of UL resource, since the resource reserved for RRR is much smaller than the one for contention based UL message with large payload. In the third aspect, from UE perspective, it minimizes the chance of UE wasting for a lot of power sending a message with large payload but failed to be decoded by eNB.

In the embodiments of this invention, different FH patterns are used to different UEs, illustrated in different filling. In order to obtain a trade-off between supported users and the collision probability, the frequency hopping (FH) patterns are based on Orthogonality/Auto-correlation/Cross-correlation of UEs. In one case, the FH pattern could be hard coded, and Available hopping pattern indices can be broadcasted in the MAC layer (header, MAC CE) or RRC. In a second case, eNB semi-statically configures FH patterns and informs to UEs. And eNB can utilize UE’s channel quality to decide the FH pattern based on channel dependent configuration.

For UE, in option 1, UE obtains the FH pattern from broadcasting information. The available FH pattern indices are broadcasted in the system information in the MAC header/CE or RRC and UE randomly chooses one from the FH pattern pool. Please note that UE should acquire/reacquire the system information before UL data transmission. In option 2, Similar to the generation of LTE preambles, FH pattern is generated according to a sequence, UE randomly inputs parameters to generate the FH pattern. In option 3, FH pattern (FH pattern index) is assigned to each UE after the UE is RRC connected with network, so that the eNB can identify a UE through the used hopping pattern.

Fig. 6 illustrates the resource allocation for RRR, response signal and reservation resources according to the embodiments of this invention. Please refer to fig. 6, UE sends a RRR in the resource 601, and receives a response signal in resource 602, and then UE transmits the UL messages in resource block 603, 604…610. And the mapping relationship between resources for RRR, response signal and the UL message are binding together.

Fig. 7 illustrates the resource allocation for RRR, response signal and reservation resources according to the embodiments of this invention. Please refer to fig. 7, in one example, UE sends a RRR on resource 710 or 720, if an response signal is received that is authorization, UE transmit UL message later in latter subframe (s) on corresponding resource 711, …or 721, …. In one example, the corresponding resources are the same in different subframes as 711, …. In another example, the cosrrespoding resources are different (with frequency hopping) in different subfames as 721…

Fig. 8 illustrates the mapping between the reservation resources and the resource for response signal according to the embodiments of this invention. For the above embodiments, the reservation resource for UL message is one-to-one mapping to the resource for ACk/NACK, as shown in fig. 8. In fig. 8, ACK/NACK for multiple reservation resources are transmitted together. For example, a special DCI format is for ACK/NACK of contention based UL message. The bits in DCI are 1-on-1 mapping to the resources of UL message. For example, the xth bit is mapped to xth resource, shown as fig. 8. The RNTI for the special DCI is cell-specific. The allocation of reservation resources could further be coverage level/channel condition specific, for example, if the reservation resources used for UL message for different coverage level or channel condition are different. Then each reservation resource may have one RNTI. Or the downlink control channel configuration is related to different coverage level. For example, in NB-IoT, the maximum repetition number of NPDCCH (Rmax) is PRACH level specific. Then the same RNTI can be used but the detection of downlink control channel could be under different configurations.

Fig. 9 illustrates the mapping between the reservation resources and the resource for response signal according to the embodiments of this invention. In this embodiment. in this embodiment, a DL message can contain at least one ACK/NACK response to at least one UL message. Within the DL message, several feedbacks can be transmitted. 1-on-1 mapping between the reservation resources for UL message and resource for response signal is also suitable in this case. Moreover, since more than one bit can be transmitted within the case, the different value could represent different meaning. For example, 0 may represents NACK, or there is UE colliding, vise versa. In this embodiment, a new MAC CE could be introduced to further explain the meaning of 0. eNB can tell the collided UEs to use separate resource if the UL message contains UE ID. For example, for ACK or NACK but no collision UE, 1 bit is enough for UEs to know the decoding status at eNB side. Another field on DL message may contains UE IDs if eNB successfully decoded more than one UE UL message at the same resource. Please refer to fig. 9. As explained previously, in one embodiment, eNB is able to detect one or more UE transmitted UL message by detecting reference signal (e.g., sounding reference signal, UL demodulation reference, preamble) , which has 1-on-1 mapping to the resource for RRR or UL message. Therefore, eNB is able to send a NACK signal based on the detected signals to the UE (s) who transmitted UL message or RRR on the corresponding UL resource.

Fig. 10 illustrates the mapping between the reservation resources and the resource for response signal according to the embodiments of this invention. In this embodiment, multiple ACK/NACK are transmitted separated. A link downlink physical channel PHICH can be introduced as resource for response signal. The PHICH resource is 1-on-1 mapping to reservation resources used for UL message, as shown in fig. 10.

In this embodiment the UE may transmit multiple TBs, e.g., each TB in on subframe, and expect ACK/NACK from eNB for each TB. If UE receives ACK, UE may transmit a new data and flush the buffer； if UE receives NACK, UE may retransmit the data in the buffer again without flushing. In this case, no DTX is expected since the resource is reserved by the UE. On the other word, eNB will expect UE to transmit a signal on the reserved resource. UE may report how many TBs, or how large a TB is to transmit to eNB so that eNB and UE share the same understanding on how long the transmission is lasting.

For for MTC/NB-IoT/mMTC device, UE may only transmitted one TB since one subframe may only carry 1 bit. UE may report the TB size to eNB in step 1 of fig. 2-fig. 4 for the TB size and/or modulation order and code rate. And in this embodiment, HARQ can also be supported.

Although fig. 8-10 are described as each bit used for one UE, but the format for ACK/NACK could be different, and used for different purpose.

For ACK/NACK responding to RRR without UL message, the ACK/NACK could be used as authorization signal, which authorizes UE to use the reservation resources, and for ACK/NACK responding to RRR with UL message, it could indicate to UE whether eNB successfully decoding the UL message.

In one case, there are different preambles in different reservation resources, if eNB does not find the associated preamble in the associated reservation resource, eNB determines there is no transmission request in the reservation resource, so eNB ignore the information in the reservation resource, or responds NACK. If eNB finds the associated preamble in the associated reservation resource, but it can not decode the information correctly, it could determine error, so responds NACK to UE, to inform UE that, I Know you have transmitted information in the reservation resource, but I have not decoded information correctly, so please retransmit the UL data, and in meanwhile, eNB stores the information in a buffer, jointly decodes the information in the buffer and the next retransmission the next time. In this case, the NACK signal could be 0, or other value, if the NACK signal is multiple bits.

Because multiple UEs could choose the same reservation resource, so the transmission is contention based, and if the multiple UEs are non orthogonal, or time division, or code division, or with different time offset, the eNB could successfully receive and decode the UL data from different UEs in the same reservation resources under some conditions.

For the UE receiving NACK which means eNB does not successfully decoding the UL data, UE could retransmit the same UL date after a fixed time, which could be called a synchronous retransmission way, and the UE could hold the UL data, and retransmit the same UL data after the UE receiving indication for retransmission from eNB, which could be called a non-synchronous retransmission way.

Fig. 11 further illustrates power control for UL non-orthogonal multiple access (NOMA) according to the embodiments of this invention. Please refer to fig. 11, UE1 and UE 2 randomly choose the same UL resource, e.g. the reservation resource 2, in order to receive better and more correct UE information, power control is performed on the transmission power for UE1 and UE2, for example, with a power threshold, UE 1 uses the power with a power offset 1 added to power threshold, and UE2 uses the power with the power threshold minus a power offset. And for eNB, because of the different power of UEs, it could differentiate different transmission from different UEs. Although UE1 and UE 2 in the same reservation resources are described for illustration, the power control could be used for UEs within different reservation resources, which is not limitation.

In this embodiment, UL NOMA is proposed to improve spectral efficiency in the embodiments of this invention, for example, Multi-user shared access (MUSA) , Resource spread multiple access (RSMA) , Sparse code multiple access (SCMA) , Pattern defined multiple access (PDMA) , Non-orthogonal coded multiple access (NCMA) , Low code rate spreading, Frequency domain spreading, Non-orthogonal multiple access (NOMA) . Some of the techniques need interference cancelation, e.g., SIC (Successive Interference Cancellation) , which may be benefit from power difference. For example, the receiver of power domain multiple access (special case of NOMA) decodes UE with higher power first and then cancel the UE with higher power to decode UE with low power. For scheduled based, it is easy for eNB to pair UEs on the same resource. However, for contention based uplink, open loop power control is expected for the first uplink transmission. in one case, it is proposed to divide into several resources and different resources corresponding to different path loss levels. However, this will increase collision possibility. in the embodiments of this invention, methods are provided to add a random power offset on top of open loop power control, comprising: UE measures DL signals and obtain path loss (e.g., RSRP) ； UE calculate transmit power based on path loss, target power (the target power in configured by eNB, e.g., in SIB) and a power offset (the random power offset is configured by eNB, e.g., in SIB) ； UE transmit UL message (preamble, UL traffic) on selected UL resource with the transmit power.

Where, the power offset for UE1/UE2 is random chosen from a discrete value set. E. g., [-3dB, 3dB] , or [-2dB, -1dB, 0dB, 1dB, 2dB] . The value can be configured by eNB. In one embodiment, the values sets are per UL resource configured. In another example, the value sets are cell-specific. In another example, the random power offset is generated with a distribution. E.g., uniform distribution within [-2dB, 2dB] . The random power offset can be turn off by eNB. For the path loss needs max Tx power, it could also adopt to a random power offset, but only has minus values or zero with in the offset, e.g, [-2dB, -1dB, 0dB] . The random power offset could be only added for the case with power ramping (that is, not max Tx power case) . Because for the UEs with max tx power, the received signal power density has very little chance to be the same. Receiver can use the power different caused by path loss. In another embodiment, the power offset is calculated based on a pre-defined rule. E.g, UE ID or RNTI, or other UE-specific /group-specific configuration. The above method can also be adopted to other non-orthogonal multiple access which could benefit from power different.

As shown as fig. 5-fig. 7, there are n resources for contention based UL, where the resource could be time/frequency/code book index/scrambling sequence/interleaver/spreading code. The chance for two UEs choose the same resource is

If m power offset if introduced, the collision possibility is further reduced to

Compared with dividing one resource pool into several subsets. This method creates power domain to distinguish UEs.

The embodiments of fig. 2-11 could be used in embodiment of fig. 1, which is not limitation.

The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. Thus, the claims are not intended to be limited to the aspects shown herein, but is to be accorded the full scope consistent with the language claims, wherein reference to an element in the singular is not intended to mean "one and only one" unless specifically so stated, but rather "one or more. " Unless specifically stated otherwise, the term "some" refers to one or more. Combinations such as "at least one of A, B, or C, " "at least one of A, B, and C, " and "A, B, C, or any combination thereof" include any combination of A, B, and/or C, and may include multiples of A, multiples of B, or multiples of C. Specifically, combinations such as "at least one of A, B, or C, " "at least one of A, B, and C, " and "A, B, C, or any combination thereof" may be A only, B only, C only, A and B, A and C, B and C, or A and B and C, where any such combinations may contain one or more member or members of A, B, or C. All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. No claim element is to be construed as a means plus function unless the element is expressly recited using the phrase "means for. "

The techniques described herein may be used for various wireless communication systems such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA and other systems. The terms "system" and "network" are often used interchangeably. A CDMA system may implement a radio technology such as Universal Terrestrial Radio Access (UTRA) , cdma2000, etc. UTRA includes Time Division Synchronous Code Division Multiple Access (TD-SCDMA) , Wideband-CDMA (W-CDMA) and other variants of CDMA. Further, cdma2000 covers IS-2000, IS-95 and IS-856 standards. A TDMA system may implement a radio technology such as Global System for Mobile Communications (GSM) . An OFDMA system may implement a radio technology such as Evolved UTRA (E-UTRA) , Ultra Mobile Broadband (UMB) , IEEE 802.11 (Wi-Fi) , IEEE 802.16 (WiMAX) , IEEE 802.20, Flash-OFDM. RTM., etc. UTRA and E-UTRA are part of Universal Mobile Telecommunication System (UMTS) . 3GPP Long Term Evolution (LTE) is a release of UMTS that uses E-UTRA, which employs OFDMA on the downlink and SC-FDMA on the uplink. UTRA, E-UTRA, UMTS, TD-SCDMA, LTE and GSM are described in documents from an organization named "3rd Generation Partnership Project" (3GPP) . Additionally, cdma2000 and UMB are described in documents from an organization named "3rd Generation Partnership Project 2" (3GPP2) . Further, such wireless communication systems may additionally include peer-to-peer (e.g., mobile-to-mobile) ad hoc network systems often using unpaired unlicensed spectrums, 802. xx wireless LAN, BLUETOOTH and any other short-or long-range, wireless communication techniques.

Although the embodiments and their advantages have been described in detail, it should be understood that various changes, substitutions, and alterations can be made herein without departing from the spirit and scope of the embodiments as defined by the appended claims. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods, and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the disclosure, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed, that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the disclosure. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps. In addition, each claim constitutes a separate embodiment, and the combination of various claims and embodiments are within the scope of the disclosure.

Claims

A method, comprising:

transmitting a reservation resource request to eNB by a UE in wireless system；

receiving ACK/NACK from the eNB； and

transmitting UL data a reservation resource to the eNB.
The method of claim 1, wherein the reservation resource is indicated explicitly or implicitly to the UE by the eNB by broadcasting or RRC signaling.
The method of claim 1, wherein the reservation resource is with a predetermined hopping pattern.
The method of claim 1, wherein the resource for ACK/NACK is associated with the reservation resource.
The method of claim 1, wherein multiple ACK/NACK for multiple UEs are localized or distributed.
A method, comprising:

transmitting a request with UL message to eNB by a UE in wireless system；

receiving ACK/NACK from the eNB； and

retransmitting UL data a reservation resource to the eNB.
The method of claim 6, wherein the NACK indicates to the UE, the UL message does not successfully decoded.
The method of claim 6, where the UL message further comprised a preamble sequence, which has a 1-on-1 mapping to the resource of transmitting the UL message.