WO2018029527A1

WO2018029527A1 - Method and apparatus for demodulation reference signal enhancement

Info

Publication number: WO2018029527A1
Application number: PCT/IB2017/001088
Authority: WO
Inventors: Ling Su; Min Zhang; Xiaoyi Wang; Frank Hsieh
Original assignee: Alcatel Lucent; Nokia Solutions And Networks Oy
Priority date: 2016-08-12
Filing date: 2017-07-26
Publication date: 2018-02-15
Also published as: CN107733599A; CN107733599B

Abstract

Embodiments of the present disclosure relate to a method and apparatus for demodulation reference signal enhancement. For instance, embodiments of the present disclosure provide a method of communication. The method comprises: determining, at a network device, whether to activate interleaved frequency division multiple access (IFDMA) for transmission of uplink demodulation reference signal (DMRS); generating an indication indicating whether the IFDMA is activated; and transmitting the indication to a terminal device. It is further disclosed a corresponding method implemented at the terminal device and a network device and terminal device capable of implementing the above method.

Description

METHOD AND APPARATUS FOR DEMODULATION REFERENCE

SIGNAL ENHANCEMENT

FIELD

[0001] Embodiments of the present disclosure generally relate to the field of wireless communications, and more specifically, to a method and apparatus for demodulation reference signal enhancement.

BACKGROUND

[0002] At present, for the long term evolution (LTE) system, it has been agreed that uplink DMRS (demodulated reference signal) transmission is to be enhanced in the current 3GPP standardization in order to support more than two orthogonal DMRS for MU-MIMO (multi-user multiple-input multiple-output) transmission with partially overlapping bandwidth allocation.

[0003] In LTE specification, a network device (such as eNB) sends DMRS configuration information to UE by using DCI (downlink control information). The current DCI formats 0 and 4 are used for the scheduling of physical uplink shared channel (PUSCH). However, DCI message in DCI format 0/4 cannot support more than two orthogonal DMRS for MU-MIMO transmission with partially overlapping bandwidth allocation for the reason that the current DCI format 0/4 has 3 bits for DMRS CS (cyclic shift)/OCC (orthogonal coverage code) configuration and can only support up to two orthogonal DMRS ports. Hence, there is a need for DMRS enhanced network device and terminal device.

[0004] IFDMA (interleaved frequency division multiple access) technology is very promising in multiplexing more than two UEs for uplink MU-MEVIO transmission. IFDMA, initially proposed by Uli Sorger et al. in 1998, achieves multiple access by allocating different subcarriers to each user (for example, odd, even subcarriers). As subcarriers of different users are totally orthogonal, multiple user interference (MUI) may be completely avoided under some circumstances. However, there are no schemes at present to apply IFDMA technology to uplink DMRS.

SUMMARY

[0005] Generally the embodiments of the present disclosure provide a method of communication for demodulation reference signal enhancement, as well as a corresponding method and apparatus.

[0006] In a first aspect, embodiments of the present disclosure provide a method of communication. The method comprises: determining, at a network device, whether to activate interleaved frequency division multiple access (IFDMA) for transmission of uplink demodulation reference signal (DMRS); generating an indication indicating whether the IFDMA is activated; and transmitting the indication to a terminal device.

[0007] In a second aspect, embodiments of the present disclosure provide a method of communication. The method comprises: receiving, at a terminal device, an indication indicating whether interleaved frequency division multiple access (IFDMA) is activated from a network device; and analyzing the indication to determine transmission mode of uplink demodulation reference signal (DMRS).

[0008] In a third aspect, embodiments of the present disclosure provide a network device. The network device comprises: a controller configured to determine whether to activate interleaved frequency division multiple access (IFDMA) for transmission of uplink demodulation reference signal (DMRS) and generate an indication indicating whether the IFDMA is activated; and a transceiver configured to transmit the indication to a terminal device.

[0009] In a fourth aspect, embodiments of the present disclosure provide a terminal device. The terminal device comprises: a transceiver configured to receive an indication indicating whether the interleaved frequency division multiple access (IFDMA) is activated from a network device; and a controller configured to analyze the indication to determine transmission mode of uplink demodulation reference signal (DMRS).

[0010] As is to be understood from the following description, according to example embodiments of the present disclosure, the network device may send an indication to the terminal devices whether the IFDMA is activated or not by applying the IFDMA technology to the uplink DMRS, so that the terminal devices that receive the indication adopt corresponding schemes (such as, utilize or not utilize IFDMA) to transmit uplink DMRS on the assigned carrier, thereby multiplexing a plurality of terminal devices for uplink MU-MIMO transmission and improving system performance.

[0011] It should be appreciated that contents as described in the summary are not intended to limit key or important features of the embodiments of the present disclosure or used to limit the scope of the present disclosure. Other features of the present disclosure will become easier to understand from the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The above and other features, advantages and aspects of various embodiments of the present disclosure will become apparent from the following detailed illustration, when taken in conjunction with the accompanying drawings in which the same or similar reference numerals denote the same or similar elements, wherein:

[0013] Fig. 1 shows an exemplary communication network in which embodiments of the present disclosure may be implemented;

[0014] Fig. 2 shows a high-level pipe diagram of signaling interaction between a network device with a terminal device for DMRS transmission according to some embodiments of the present disclosure;

[0015] Fig. 3 shows a flow diagram of an exemplary communication method according to some embodiments of the present disclosure;

[0016] Fig. 4A and Fig. 4B show a schematic diagram of allocating subcarriers not using the extension bit in the cyclic shift field according to some embodiments of the present disclosure, and Fig. 4C and Fig. 4D show a schematic diagram of allocating subcarriers not using the extension bit in the cyclic shift field according to improved embodiments of the present disclosure;

[0017] Fig. 5A and Fig. 5B show a schematic diagram of allocating subcarriers using the extension bit in the cyclic shift field according to some embodiments of the present disclosure;

[0018] Fig. 6 shows a flow diagram of an exemplary communication method according to some other embodiments of the present disclosure;

[0019] Fig. 7 shows a block diagram of an apparatus according to some embodiments of the present disclosure;

[0020] Fig. 8 shows a block diagram of an apparatus according to some embodiments of the present disclosure;

[0021] Fig. 9 shows a block diagram of a device according to some embodiments of the present disclosure. [0022] Through the drawings, identical or similar reference numbers represent the same or similar elements.

DETAILED DESCRIPTION

[0023] Embodiments of the present disclosure will be described in more detail with reference to the accompanying drawings, in which some embodiments of the present disclosure have been illustrated. However, the present disclosure can be implemented in various manners, and thus should not be construed to be limited to the embodiments disclosed herein. On the contrary, those embodiments are provided for the thorough and complete understanding of the present disclosure. It should be understood that the accompanying drawings and embodiments of the present disclosure are merely for the illustration purpose, rather than limiting the protection scope of the present disclosure.

[0024] The term "network device" used herein refers to other entities or nodes having particular functions in the base station or communication network. The term "base station" used herein may represent a node B (NodeB or NB), an Evolved Node B (eNodeB or eNB), a remote radio unit (RRU), a radio frequency head (RH), a remote radio head (RRH), a relay, or a low power node such as a Femto station and a Pico station, and the like. In the context of the present disclosure, for the sake of convenience, the term "network device" and "base station" can be used interchangeably and probably eNB is mainly taken as an example of the network device.

[0025] The term "terminal device" or "user equipment" (UE) used herein refers to any terminal device that can perform wireless communication with base stations or with each other. As an example, the terminal device may comprise a mobile terminal (MT), a subscriber station (SS), a portable subscriber station (PSS), a mobile station (MS), or an access terminal (AT), and on-board devices as above. In the context of the present disclosure, for the sake of convenience, terms "terminal device" and "user equipment" can be used interchangeably.

[0026] The terms "comprise", "include" and their variants used here are to be read as open terms that mean "include, but is not limited to". The term "based on" is to be read as "based at least in part on". The term "one embodiment" is to be read as "at least one embodiment"; the term "another embodiment" is to be read as "at least one other embodiment". Definitions of other terms will be presented in description below.

[0027] Although in 3GPP standard, an orthogonal DMRS that supports two UEs paired for MU-MIMO has been proposed, the number of UEs is likely to be expanded as needed. The current DCI formats 0 and 4 support orthogonal DMRS of two UEs, namely, two UEs are allocated with different OCCs. As a potential alternative solution, if in combination with IFDMA technology, the number of supported UEs may be at least doubled. For example, when three UEs are paired for uplink MU-MIMO, two UEs are allocated with the same OCC code and the other UE is allocated with another different OCC code. For two UEs allocated with the same OCC code, IFDMA may be used to maintain orthogonal DMRS. For instance, the two UEs may perform uplink DMRS transmission on odd subcarriers and even subcarriers, respectively. However, the current DCI formats 0 and 4 cannot provide necessary information for allocating subcarriers for UE.

[0028] Therefore, an effective method is required to enable the UE to learn if IFDMA is activated. Furthermore, when the IFDMA is activated, UE needs to learn the subcarriers used for uplink DMRS transmission, for example, they are odd subcarriers or even subcarriers when the repetition factor (RPF) is 2. [0029] To at least partially address these and other potential problems, embodiments of the present disclosure provide a new communication method and a corresponding apparatus. According to the embodiments of the present disclosure, the network device may determine whether to activate the IFDMA for uplink DMRS transmission. Then, the network device may generate an indication indicating whether the IFDMA is activated and transmitting the indication to the terminal device. It should be noted that the indication indicating whether the IFDMA is activated to be sent to each terminal device may be different, namely, the indication that IFDMA is activated may be sent to one or more terminal devices thereof and the indication that IFDMA is not activated may be sent to other terminal devices.

[0030] In this manner, the network device may send the indication on whether the IFDMA is activated to the terminal devices so that the terminal devices that receive the indication may adopt the corresponding schemes to transmit uplink DMRS on the allocated carrier, thereby multiplexing a plurality of terminal devices for uplink MU-MIMO transmission and improving system performance.

[0031] Fig. 1 shows an exemplary communication network 100 in which embodiments of the present disclosure may be implemented. The communication network 100 includes a network device 150 and a plurality of terminal devices, namely, a first terminal device 110, a second terminal device 120, a third terminal device 130 and a fourth terminal device 140. The terminal devices 110-140 may communicate with the network device 150 and attempt to use the same resource blocks.

[0032] It is to be understood that the number of network devices and terminal devices shown in Fig. 1 is merely for illustration purpose rather than limiting. The network 100 may include any proper number of network devices and terminal devices. In particular, the embodiments of the present disclosure depicted in the following text may apply to individual user equipment.

[0033] According to the embodiments of the present disclosure, the network device 150 may pair the first terminal device 110, the second terminal device 120, the third terminal device 130, and the fourth terminal device 140 together for the uplink MU-MIMO. It is to be understood that apart from paring the first terminal device 110, the second terminal device 120, the third terminal device 130, and the fourth terminal device 140, the network device 150 may also perform pairing in different manners. As an example, as stated above, it is possible to pair three terminal devices together, i.e., to pair the first terminal device 110, the second terminal device 120, and the third terminal device 130 together for the uplink MU-MIMO.

[0034] The communication in network 100 may be implemented in accordance with any appropriate communication protocol, including without limitation to, the first generation (1G), the second generation (2G), the third generation (3G), the fourth generation (4G), the fifth generation (5G), and other cellular communication protocol, wireless local area network communication protocol such as Institute for Electrical and Electronics Engineers (IEEE) 802.11, and/or any other protocols that are currently known or to be developed later. Furthermore, the communication utilizes any appropriate wireless communication technology, including without limitation to, code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), frequency division duplexing (FDD), time division duplexing (TDD), multiple input multiple output (MIMO), orthogonal frequency division multiplexing (OFDM), and/or any other technology that is currently known or to be developed later.

[0035] According to the embodiments of the present disclosure, the network device 150 may determine whether to activate the IFDMA for uplink DMRS transmission. Next, the network device 150 may generate an indication on whether the IFDMA is activated and send the indication to the first terminal device 110, the second terminal device 120, the third terminal device 130, and the fourth terminal device 140. As stated above, the indication on whether the IFDMA is activated sent to the first terminal device 110, the second terminal device 120, the third terminal device 130, and the fourth terminal device 140 may be different. Namely, the indication that IFDMA is activated may be sent to the first terminal device 110 and the second terminal device 120 and the indication that the IFDMA is activated may be sent to the third terminal device 130 and the fourth terminal device 140. The first terminal device 110 and the second terminal device 120 are assigned with the same OCC code while the third terminal device 130 and the fourth terminal device 140 are assigned with another OCC code.

[0036] For two UEs assigned with the same OCC code, IFDMA may be used to maintain orthogonal DMRS. For example, the two UEs may perform uplink DMRS transmission on odd subcarriers and even subcarriers, respectively. Since the network device 150 sends the indication on whether the IFDMA is activated to the first terminal device 110, the second terminal device 120, the third terminal device 130, and the fourth terminal device 140, the terminal devices that receive the indication adopt the corresponding schemes to transmit uplink DMRS on the assigned carrier, thereby multiplexing the first terminal device 110, the second terminal device 120, the third terminal device 130, and the fourth terminal device 140 for uplink MU-MIMO transmission and improving system performance.

[0037] Fig. 2 shows a high-level pipe diagram of signaling interaction between the network device 150 and one of the terminal devices 110 for DMRS transmission according to some embodiments of the present disclosure. As shown in Fig. 2, before performing uplink DMRS, the network device 150 sends an indication on whether the IFDMA is activated to the paired plurality of terminal devices. Fig. 2 only schematically illustrates one terminal device among a plurality of terminal devices, namely, the first terminal device 110 analyses the indication and transmits uplink DMRS on the subcarriers assigned according to the indication. The indication on whether the IFDMA is activated sent to the terminal devices may be different.

[0038] The principles and detailed embodiments of the present disclosure will be illustrated in detail from the sides of the network device 150 and the first terminal device 110 with reference to Figs. 3-6, respectively. First of all, reference is made to Fig. 3 which shows a flow diagram of an exemplary communication method 300 according to some embodiments of the present disclosure. It is to be appreciated that the method 300 may be executed at the network device 150, for instance, shown in Fig. 1 and Fig. 2. For the discussion purpose, the method 300 will be illustrated with reference to Fig. 1 and Fig. 2. [0039] In step 305, the network device 150 is configured to determine whether to activate IFDMA for the transmission of the uplink DMRS. In step 310, the network device 150 is configured to generate an indication indicating whether the IFDMA is activated. In step 315, the network device 150 is configured to transmit the indication to the first terminal device HO.

[0040] In this manner, the network device 150 may send the indication indicating whether the IFDMA is activated to the first terminal device 110 so that the first terminal device 110 that receives the indication may adopt the corresponding scheme to transmit uplink DMRS on the assigned carrier, thereby utilizing IFDMA technology for uplink DMRS transmission and enhancing uplink DMRS. The processing of the terminal device side will be described in detail in the following text with reference to Fig. 6.

[0041] In some embodiments, step 310 may include establishing, by the network device 150, one or more higher level parameters to indicate whether the IFDMA is activated, for example, establishing, on the radio resource control (RRC) layer, one or more parameters to indicate whether the IFDMA is activated. When parameters at higher level indicate that the IFDMA is activated, Table 1 below, for instance, may be used to allocate subcarriers for the terminal device to transmit uplink DMRS.

Table 1

[0042] When parameters at higher level indicate that IFDMA is not activated, the current table may be used (such as Release 10). In Table 1, comb 1 and comb 2 of IFDMA comb may be used to represent odd subcarriers and even subcarriers, respectively, and vice versa. As an example, combl represents odd subcarriers and comb2 represents even subcarriers. An exemplary allocation method will be described in detail in the following text with reference to Table 2 and Fig. 4A and Fig. 4B. It is to be appreciated that there are multiple manners of allocating IFDMA subcarriers. Therefore, those skilled in the art may make other modifications and improvement under the teaching of the allocation manner described in the present disclosure.

[0043] In this manner, besides enhancing the uplink DMRS, it is convenient to make changes to the current system, particularly without changes to the traditional DCI configuration.

[0044] In some embodiments, step 310 may further include generating, by the network device 150, a DCI indicating whether the IFDMA is activated. In this manner, though DCI needs to be changed, besides enhancing uplink DMRS, it is possible to make more flexible configuration in response to the change of the system, since the adjustment is made to the lower layer. As such, the allocation of the subcarriers may be further optimized.

[0045] In some embodiments, in response to IFDMA being activated, the network device 150 may be configured to generate DCI to indicate subcarriers for the first terminal device 110 to perform uplink DMRS transmission. Specifically, the schemes indicating the assigned subcarriers may be divided into two types: the first type, adding no DCI bit, namely, not using extension bits in the cyclic shift field but re-allocating subcarriers with the current cyclic shift field; the second type, adding the DCI bit, namely, using the extension bit in the cyclic shift field, or other bits in the DCI. The bit may be used to indicate whether the IFDMA is activated in order to allocate the subcarriers.

[0046] The first type of schemes for allocating subcarriers will be described in the following text, namely, not adding DCI bits and not changing CS/OCC configuration while only adding implicit IFDMA comb indications in the CS field. Table 2 below shows the specific allocation of the subcarriers.

Table 2

S field in DCI (2)

OCC IFDMA configuration

000 0 6 3 9 [1 i] [1 i] [1 -1] [1 -1] no IFDMA

001 6 0 9 3 [1 -1] [1 -1] [1 i] [1 i] no IFDMA

010 3 9 6 0 [1 -1] [1 -1] [1 i] [1 i] odd subcarriers

011 4 10 7 1 [1 i] [1 i] [1 i] [1 i] no IFDMA

100 2 8 5 11 [1 i] [1 i] [1 i] [1 i] even subcarriers

101 8 2 11 5 [1 -1] [1 -1] [1 -1] [1 -1] even subcarriers

110 10 4 1 7 [1 -1] [1 -1] [1 -1] [1 -1] no IFDMA

111 9 3 0 6 [1 i] [1 i] [1 -1] [1 -1] odd subcarriers n ,(2)

[0047] In Table 2, DMRS, l represents the specific value of cyclic shift (CS). The four columns of values represent four layers and the four columns in OCC column also represent these four layers. It is to be appreciated that the number of layers described herein may be varied and expanded. Typically, generating DCI to allocate IFDMA subcarriers includes: creating CS field in the DCI, where information in the CS field is used to specify that the first terminal device 110 is allocated with one or more subcarriers each having an odd sequential number and the second terminal device 120 is allocated with one or more subcarriers each having an odd sequential number, or the first terminal device 110 is allocated with one or more subcarriers each having an even sequential number and the second terminal device 120 is allocated with one or more subcarriers each having an odd sequential number. Meanwhile, the first terminal device 110 and the second terminal device 120 are assigned with the same OCC (as may be seen from Fig. 2, each pair of odd and even subcarriers has OCC with the same first and second layer). As stated above, CS/OCC configuration is not changed. The last column of the table shows the indication of the IFDMA combs, namely, indication of odd subcarriers or even subcarriers when the repetition factor is 2. The method for allocating IFDMA subcarriers will be described in the following text with reference to Fig. 4A and Fig. 4B.

[0048] Fig. 4A and Fig. 4B show a schematic diagram of allocating subcarriers not using the extension bit in the cyclic shift field according to some embodiments of the present disclosure. As an example, lines of the first and second layers being [1 1] in OCC are selected from Table 2 so that the corresponding values of the first column in the CS specific values may be found in the four lines, namely, 0, 4, 2, 9. Then, as shown in Fig. 4A, 9 has the maximum separation distance with respect to 0, 4, 2 and thus, 9 may be chosen as the odd subcarrier. Furthermore, since the separation distances from 2 and 4 to 9 are the same and larger than that from 0 to 9, any one of them may be chosen as the even subcarrier. Here, 2 is chosen as the even subcarrier. The remaining 0 and 4 are selected as no-IFDMA. After that, lines of the first and second layers being [1 -1] in OCC are selected from Table 2, and the corresponding values of the first column are found from CS specific values, namely, 6, 3, 8, 10. Then, as shown in Fig. 4B, 3 has the maximum separation distance with respect to 6, 8 and 10 and thus, 3 may be selected as the odd subcarrier. Moreover, since the separation distances from 8 and 10 to 3 are the same and larger than that from 6 to 3, any one of them may be chosen as the even subcarrier. 8 is chosen herein as the even subcarrier and the remaining 6 and 10 are selected as no-IFDMA. In this way, the allocation of IFDMA subcarriers is completed. It is to be appreciated that there are various ways of allocating IFDMA subcarriers. Hence, those skilled in the art may make other modifications and improvement under the teaching of the allocation manner described in the present disclosure.

[0049] As another example, Fig. 4C and Fig. 4D show a schematic diagram of allocating subcarriers not using the extension bit in the cyclic shift field according to improved embodiments of the present disclosure. As shown in Fig. 4C and Fig. 4D, the positions of 2 and 3 in the figure are swapped. As shown in Fig. 4C, 9 and 3 have the maximum separation distance and as shown in Fig. 4D, 8 and 2 have the maximum separation distance. Therefore, subcarriers allocated to the paired terminal devices according to the embodiments have better correlation. Table 3 below shows the specific allocation of the improved subcarriers. It is clear that CS values in line 3 and line 5 of Table 3 are swapped.

Table 3

[0050] As another example, the four lines of CS value

in the first layer being 0,

6, 3, 9 may be chosen for allocating IFDMA subcarriers, as shown in Table 4 below. It may be seen that the difference between Table 4 and Table 2 is that the four CS fields are chosen for IFDMA configuration.

Table 4

(2)

CS field in DCI OCC IFDMA configuration

000 0 6 3 9 [1 i] [1 i] [1 -1] [1 -1] odd subcarriers

001 6 0 9 3 [1 -1] [1 -1] [1 i] [1 i] odd subcarriers 010 3 9 6 0 [1 -1] [1 -1] [1 i] [1 i] even subcarriers

Oil 4 10 7 1 [1 i] [1 i] [1 i] [1 i] no IFDMA

100 2 8 5 11 [1 i] [1 i] [1 i] [1 i] no IFDMA

101 8 2 11 5 [1 -1] [1 -1] [1 -1] [1 -1] no IFDMA

110 10 4 1 7 [1 -1] [1 -1] [1 -1] [1 -1] no IFDMA

111 9 3 0 6 [1 i] [1 i] [1 -1] [1 -1] even subcarriers

[0051] Besides, DMRS with a length of 6 in NB-loT in R13 (Release 13) may also be allocated with subcarriers. As the cyclic shift shown in Tables 1-4 has 12 different values while DMRS with a length of 6 in NB-loT only has four different cyclic shift values 0, 1, 2, 4. The four values may be mapped as 0, 2, 4, 8. The specific allocation manner may be known with reference to the depiction of Fig. 4A and Fig. 4B. The specific allocation result of IFDMA subcarriers is shown in Fig. 5. Besides, those skilled in the art may also make changes to the table, for instance, changing Table 5 with reference to the improvement manner of Fig. 3. Furthermore, Table 5 may be merged with Table 1, Table 2, Table 3 or Table 4, respectively. The details are omitted here.

Table 5

[0052] Now, the second type of schemes of allocating subcarriers, namely, adding DCI bits, will be discussed in the following text. For example, the extension bit in the cyclic shift field may be used and other bits in DCI may also be utilized to indicate whether the IFDMA is activated to allocate the subcarriers. Fig. 5 A and Fig. 5B show a schematic diagram of allocating subcarriers using the extension bit in the cyclic shift field according to some embodiments of the present disclosure. The specific allocation manner may be known with reference to the depiction of Fig. 4 and Fig. 4B. Table 6 below illustrates the specific allocation of the subcarriers with an example of adding an extension bit before the original three bits in the CS field. The extension bit of 0 may represent no IFDMA being used for DMRS and the extension bit of 1 may represent that IFDMA is used for

Furthermore, Table 6 may be merged with Table 5, details of which are omitted here.

Table 6

[0053] As there are 8 new entries for IFDMA, it is permitted that the repetition factor of IFDMA is 4 and there are two OCC codes. 12 subcarriers in a resource block may be divided into four groups of combs. If only the repetition factor of 2 is use, comb 1 and comb 3 fall back to odd subcarriers, and comb 2 and comb 4 refer to even subcarriers. Furthermore, those skilled in the art may make changes to this table, for instance, changing Table 6 with reference to the improvement manner of Table 3.

[0054] Those skilled in the art should note that the physical hybrid-ARQ indicator channel

(PHICH) is represented by the indicator pair ("PMCH > ⁿmicH ⁾ , where ⁿ cH is PHICH class number and "PHICH is orthogonal sequence index in the class, which is defined by the following equation: group _

n PHICH - nPHICH -

where ^UDMRS is mapped as the cyclic shift of the DMRS field with uplink DCI format 4 in the latest physical downlink control channel (PDCCH) (see Table 7, namely, Table 9.1-2.2 in the standard).

Table 7

[0055] As in Table 7 above, the cyclic shift of DMRS field is changed as 4. To continue to use the current Table 7, only the last three bits of cyclic shift are used to obtain ^HDMRS SO that the extension bits may be neglected and PHICH indicator conflict may be avoided.

[0056] Fig. 6 shows a flow diagram of an exemplary communication method 600 according to some embodiments of the present disclosure. It may be appreciated that the method 600 may be executed at the first terminal device 110 shown, for example, in Fig. 1 and Fig. 2. For the discussion purpose, the method 600 will be described with reference to Fig. 1 and Fig. 2.

[0057] In step 605, the first terminal device 110 is configured to receive an indication indicating whether the IFDMA is activated from the network device 140. In step 610, the first terminal device 110 is configured to analyze the indication to determine the transmission mode of the uplink DMRS.

[0058] As stated above, in some embodiments, step 610 may include analyzing, by the first terminal device 110, parameters created at higher layers to indicate whether the IFDMA is activated, for example, analyzing parameters created by the radio resource control (RRC) layer to indicate whether the IFDMA is activated. In this manner, besides enhancing the uplink DMRS, it is convenient to make changes to the current system, particularly without changes to the traditional DCI configuration.

[0059] In some embodiments, step 610 may further include analyzing, by the first terminal device 110, a downlink DCI indicating whether the IFDMA is activated. In this manner, though DCI needs to be changed, besides enhancing uplink DMRS, it is possible to make more flexible configuration in response to the change of the system, since the adjustment is made to the lower layer. As such, the allocation of the subcarriers may be further optimized.

[0060] In some embodiments, in response to IFDMA being activated, the first terminal device 110 may be configured to analyze the DCI to determine subcarriers for the first terminal device 110 to perform uplink DMRS transmission. As stated above, the schemes indicating the assigned subcarriers may be divided into two types.

[0061] In some embodiments, analyzing, by the first terminal device 110, the DCI to determine the subcarriers may include: analyzing a cyclic shift field in the DCI, where information in the cyclic shift field is used to specify that the first terminal device 110 is allocated with a subcarrier having an odd sequential number and the second terminal device 120 is allocated with a subcarrier having an even sequential number, or the first terminal device 110 is allocated with a subcarrier having an even sequential number and the second terminal device 120 is allocated with a subcarrier having an odd sequential number.

[0062] In some embodiments, in response to IFDMA being activated, the first terminal device 110 may be configured to analyze the extension bit of the cyclic shift field of DCI to determine if IFDMA is activated.

[0063] It is to be understood that the operations executed by the network device 150 and the relevant features described with reference to Figs. 3-5 are also applicable to method 600 executed by the first terminal device 110 and have the same effect, details of which are omitted here.

[0064] Fig. 7 shows a block diagram of an apparatus 700 according to some embodiments of the present disclosure. It may be appreciated that apparatus 700 may be implemented at the side of the network device 150 shown in Fig. 1 and Fig. 2. As shown in Fig. 7, apparatus 700 (such as the network device 150) includes: a determining unit 705 configured to determine whether to activate IFDMA for uplink DMRS transmission; a generating unit 710 configured to generate an indication indicating whether the IFDMA is activated; and a sending unit 715 configured to send the indication to at least one terminal device (such as the first terminal device 110) among the first terminal device 110, the second terminal device 120, the third terminal device 130 and the fourth terminal device 140.

[0065] In some embodiments, the generating unit 710 further includes creating parameters at the RRC layer to indicate whether the IFDMA is activated.

[0066] In some embodiments, the generating unit 710 further includes generating a DCI indicating whether the IFDMA is activated. In some embodiments, generating DCI includes generating, in response to IFDMA being activated, the DCI to indicate subcarriers for performing, by the first terminal device 110, the uplink DMRS transmission. In some embodiments, generating DCI to indicate subcarriers includes: creating a cyclic shift field in DCI, where information in the cyclic shift field is used to specify that the first terminal device 110 is allocated with a subcarrier having an odd sequential number is odd and the second terminal device 120 is allocated with a subcarrier having an even sequential number, or the first terminal device 110 is allocated with a subcarrier having an even sequential number and the second terminal device 120 is allocated with a subcarrier having an odd sequential number; and allocating the same orthogonal coverage code (OCC) to the first terminal device 110 and the second terminal device 120.

[0067] In some embodiments, generating DCI includes: using an extension bit of a cyclic shift field of the DCI to indicate whether the IFDMA is activated. In some embodiments, in response to the DCI being sent, the extension bit is neglected. [0068] Fig. 8 shows a block diagram of an apparatus 800 according to some embodiments of the present disclosure. It may be appreciated that apparatus 800 may be implemented at a side of the first terminal device 110 shown in Fig. 1 and Fig. 2. As shown in this figure, apparatus 800 (such as the first terminal device 110, or the second terminal device 120, the third terminal device 130, and the fourth terminal device 140 shown in Fig. 1) includes: an indication receiving unit 805 configured to receive the indication indicating whether the IFDMA is activated from the network device 150; and a signal analyzing unit 810 configured to analyze the indication to determine the transmission mode of the uplink DMRS.

[0069] In some embodiments, the indication analyzing unit 810 further includes analyzing parameters created at the RRC layer to indicate whether the IFDMA is activated. [0070] In some embodiments, the indication analyzing unit 810 further includes a DCI analyzing the indication indicating whether the IFDMA is activated. In some embodiments, analyzing DCI includes analyzing, in response to IFDMA being activated, the DCI to determine subcarriers for performing, by the first terminal device 110, the uplink DMRS transmission. In some embodiments, analyzing the DCI to determine subcarriers includes: analyzing a cyclic shift field in the DCI, where information in the cyclic shift field is used to specify that the first terminal device 110 is allocated with a subcarrier having an odd sequential number and the second terminal device 120 is allocated with a subcarrier having an even sequential number, or the first terminal device 110 is allocated with a subcarrier having an even sequential number and the second terminal device 120 is allocated with a subcarrier having an odd sequential number. The first terminal device 110 and the second terminal device 120 are allocated with the same orthogonal coverage code (OCC). [0071] In some embodiments, analyzing DCI includes: analyzing an extension bit of a cyclic shift field of the DCI to determine whether the IFDMA is activated. In some embodiments, in response to the DCI being analyzed, the extension bit is neglected.

[0072] It should be appreciated that each unit of the apparatus 700 and the apparatus 800 corresponds to each step in method 300 and 600 described with reference to Figs. 1- 6. Thus, the operations and features described above with reference to Figs. 1- 6 are also applicable to the apparatus 700 and the apparatus 800 as well as units contained therein and have the same effect, details of which are omitted here.

[0073] The units included in the apparatus 700 and the apparatus 800 may be implemented in various manners, including software, hardware, firmware or any combination thereof. In an embodiment, one or more units may be implemented with software and/or firmware, for instance, the machine-executable instructions stored on the storage medium. In addition to or instead of machine-executable instructions, parts or all the units in the apparatus 700 and the apparatus 800 may be implemented, at least in part, by one or more hardware logic components. For example, and without limitation, illustrative types of hardware logic components that can be used include Field-programmable Gate Arrays (FPGAs), Application- specific Integrated Circuits (ASICs), Application- specific Standard Products (ASSPs), System-on-a-chip systems (SOCs), Complex Programmable Logic Devices (CPLDs), etc.

[0074] The units shown in Fig. 7 and Fig. 8 may be implemented, partially or entirely, as a hardware module, a software module, a firmware module or any combination thereof. In particular, in some implementations, the flows, methods or processes described above may be implemented by hardware in a base station or terminal device. For example, the base station or terminal device may implement the method 300 and 600 by means of its transmitter, receiver, transceiver and/or processor or controller. [0075] Fig. 9 shows a block diagram of an apparatus 900 which is applicable to implement the embodiments of the present disclosure. Apparatus 900 may be used to implement the network device, such as the network device 150 shown in Fig. 1 and Fig. 2; and/or to implement the terminal device, such as the first terminal device 110 shown in Fig. 1 and Fig. 2.

[0076] As shown, apparatus 900 includes a controller 910 which controls the operations and functions of apparatus 900. For example, in some embodiments, the controller 910 may perform various operations by means of instructions 930 stored in the memory 920 coupled therewith. The memory 920 may be any proper type adapted to the local technical environment and may be implemented using any proper data storage techniques, including but not limited to, a semiconductor-based storage device, a magnetic storage device and system, an optical storage device and a system. Though only one memory unit is shown in Fig. 9, there may be a plurality of physically different memory units in apparatus 900.

[0077] The controller 910 may be of any appropriate type that is applicable to a local technical environment and may include, but not limited to, a general-purpose computer, a special-purpose computer, a microprocessor, a digital signal processor (DSP), as well as one or more processors in a processor based multi-core processor architecture. The apparatus 900 may also include a plurality of controllers 910 which are coupled to the transceiver 940 that may implement information reception and transmission by means of one or more antennas 950 and/or other components.

[0078] When the apparatus 900 is used as the network device 150, the controller 910 and transceiver 940 may operate in cooperation to implement the method 300 described with reference to Fig. 3 in the above text. When the apparatus 900 is used as the first terminal device 110, the controller 910 and transceiver 940 may operate in cooperation to implement the method 600 described with reference to Fig. 6 in the above text. For example, in some embodiments, all the acts involving data/information reception and transmission described above may be implemented by transceiver 940 while the other acts may be executed by the controller 910. All the features described above with reference to Fig. 3 and Fig. 6 are applicable to apparatus 900, thus omitted here.

[0079] Generally, the various exemplary embodiments of the present disclosure may be implemented in hardware or application-specific circuit, software, logic, or in any combination thereof. Some aspects may be implemented in hardware, while the other aspects may be implemented in firmware or software executed by a controller, a microprocessor or other computing devices. When various aspects of the embodiments of the present disclosure are illustrated or described into block diagrams, flow charts, or other graphical representations, it would be understood that the block diagrams, apparatus, system, technique or method described here may be implemented, as non-restrictive examples, in hardware, software, firmware, dedicated circuit or logic, common software or controller or other computing devices, or some combinations thereof.

[0080] As an example, the embodiments of the present disclosure may be described in a context of machine-executable instructions which are included, for instance, in the program module executed in the device on a target real or virtual processer. Generally, a program module includes routine, program, bank, object, class, component, data structure and so on and performs a particular task or implements a particular abstract data structure. In the embodiments, the functions of the program modules may be combined or divided among the described program modules. The machine executable instructions for the program module may be executed locally or in a distributed device. In the distributed device, the program module may be located between the local and remote storage media.

[0081] The computer program code for implementing the method of the present disclosure may be complied with one or more programming languages. These computer program codes may be provided to a general-purpose computer, a dedicated computer or a processor of other programmable data processing apparatuses, such that when the program codes are executed by the computer or other programmable data processing apparatuses, the functions/operations prescribed in the flow chart and/or block diagram are caused to be implemented. The program code may be executed completely on a computer, partially on a computer, partially on a computer as an independent software packet and partially on a remote computer, or completely on a remote computer or server.

[0082] In the context of the present disclosure, the machine-readable medium may be any tangible medium including or storing a program for or about an instruction executing system, apparatus or device. The machine-readable medium may be a machine-readable signal medium or machine-readable storage medium. The machine-readable medium may include, but not limited to, electronic, magnetic, optical, electro-magnetic, infrared, or semiconductor system, apparatus or device, or any appropriate combination thereof. More detailed examples of the machine-readable storage medium include, an electrical connection having one or more wires, a portable computer magnetic disk, hard drive, random-access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical storage device, magnetic storage device, or any appropriate combination thereof. [0083] Further, while operations are depicted in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In certain circumstances, multitasking and parallel processing may be advantageous. Likewise, while several specific implementation details are contained in the above discussions, these should not be construed as limitations on the scope of the present disclosure, but rather as descriptions of features that may be specific to particular embodiments. Certain features that are described in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment may also be implemented in multiple embodiments separately or in any suitable sub-combination.

[0084] Although the subject matter has been described in language that is specific to structural features and/or method actions, it is to be understood the subject matter specified in the appended claims is not limited to the specific features or acts described above. On the contrary, the above-described specific features and actions are disclosed as example forms of implementing the claims.

Claims

I/We Claim:

1. A method of communication, comprising:

determining, at a network device, whether to activate interleaved frequency division multiple access (IFDMA) for transmission of uplink demodulation reference signal (DMRS); generating an indication indicating whether the IFDMA is activated; and

transmitting the indication to a terminal device.

2. The method according to Claim 1, wherein generating the indication indicating whether the IFDMA is activated comprises:

creating parameters at a radio resource control (RRC) layer to indicate whether the IFDMA is activated.

3. The method according to Claim 1, wherein generating the indication indicating whether the IFDMA is activated comprises:

generating downlink control information (DCI) indicating whether the IFDMA is activated.

4. The method according to Claim 3, wherein generating the DCI comprises:

in response to the IFDMA being activated, generating the DCI to indicate subcarriers used for performing, by the terminal device, the transmission of uplink DMRS.

5. The method according to Claim 4, wherein generating the DCI to indicate the subcarriers comprises:

creating a cyclic shift field in the DCI, wherein information in the cyclic shift field is used to specify that the terminal device is allocated with a subcarrier having an odd sequential number and another terminal device is allocated with a subcarrier having an even sequential number, or that the terminal device is allocated with a subcarrier having an even sequential number and another terminal device is allocated with a subcarrier having an odd sequential number; and

allocating a same orthogonal coverage code (OCC) to the terminal device and the other terminal device.

6. The method according to Claim 3, wherein generating the DCI comprises: using an extension bit of a cyclic shift field of the DCI to indicate whether the IFDMA is activated.

7. The method according to Claim 6, wherein in response to the DCI being transmitted, the extension bit is neglected.

8. A method of communication, comprising:

receiving, at a terminal device, an indication indicating whether interleaved frequency division multiple access (IFDMA) is activated from a network device; and

analyzing the indication to determine transmission mode of uplink demodulation reference signal (DMRS).

9. The method according to Claim 8, wherein analyzing the indication comprises:

analyzing parameters created by a radio resource control (RRC) layer to indicate whether the IFDMA is activated.

10. The method according to Claim 8, wherein analyzing the indication comprises: analyzing downlink control information (DCI) indicating whether the IFDMA is activated.

11. The method according to Claim 10, wherein analyzing the DCI comprises:

in response to the IFDMA being activated, analyzing the DCI to determine subcarriers used for performing, by the terminal device, transmission of uplink DMRS.

12. The method according to Claim 11, wherein analyzing the DCI to determine the subcarriers comprises:

analyzing a cyclic shift field in the DCI, wherein information in the cyclic shift field is used to specify that the terminal device is allocated with a subcarrier having an odd sequential number and another terminal device is allocated with a subcarrier having an even sequential number, or that the terminal device is allocated with a subcarrier having an even sequential number and another terminal device is allocated with a subcarrier having an odd sequential number.

13. The method according to Claim 10, wherein analyzing the DCI comprises: analyzing an extension bit of a cyclic shift field of the DCI to determine whether the IFDMA is activated.

14. The method according to Claim 13, wherein in response to the DCI being analyzed, the extension bit is neglected.

15. A network device, comprising:

a controller configured to determine whether to activate interleaved frequency division multiple access (IFDMA) for transmission of uplink demodulation reference signal (DMRS) and generate an indication indicating whether the IFDMA is activated; and

a transceiver configured to transmit the indication to a terminal device.

16. The network device according to Claim 15, wherein generating the indication indicating whether the IFDMA is activated comprises:

creating parameters at a radio resource control (RRC) layer to indicate whether the

IFDMA is activated.

17. The network device according to Claim 15, wherein generating the indication indicating whether the IFDMA is activated comprises:

18. The network device according to Claim 17, wherein generating the DCI comprises: generating, in response to the IFDMA being activated, the DCI to indicate subcarriers used for performing, by the terminal device, the transmission of uplink DMRS.

19. The network device according to Claim 18, wherein generating the DCI to indicate the subcarriers comprises:

creating a cyclic shift field in the DCI, wherein information in the cyclic shift field is used to specify that the terminal device is allocated with a subcarrier having an odd sequential number and another terminal device is allocated with a subcarrier having an even sequential number, or that the terminal device is allocated with a subcarrier having an even sequential number and another terminal device is allocated with a subcarrier having an odd sequential number; and allocating a same orthogonal coverage code (OCC) to the terminal device and the other terminal device.

20. The network device according to Claim 17, wherein generating the DCI comprises: using an extension bit of a cyclic shift field of the DCI to indicate whether the IFDMA is activated.

21. The network device according to Claim 20, wherein in response to the DCI being transmitted, the extension bit is neglected.

22. A terminal device, comprising:

a transceiver configured to receive an indication indicating whether interleaved frequency division multiple access (IFDMA) is activated from a network device; and

a controller configured to analyze the indication to determine transmission mode of uplink demodulation reference signal (DMRS).

23. The terminal device according to Claim 22, wherein analyzing the indication comprises:

24. The terminal device according to Claim 22, wherein analyzing the indication comprises:

analyzing downlink control information (DCI) indicating whether the IFDMA is activated.

25. The terminal device according to Claim 24, wherein analyzing the DCI comprises: in response to the IFDMA being activated, analyzing the DCI to determine subcarriers user for performing, by the terminal device, transmission of uplink DMRS.

26. The terminal device according to Claim 25, wherein analyzing the DCI to determine the subcarriers comprises:

27. The terminal device according to Claim 24, wherein analyzing the DCI comprises: analyzing an extension bit of a cyclic shift field of the DCI to determine whether the

IFDMA is activated.

28. The terminal device according to Claim 27, wherein in response to the DCI being analyzed, the extension bit is neglected.