TECHNICAL FIELD

[0002] The present disclosure generally relates to the field of wireless network communications, and more particularly, to deploying LTE-M in coexistence with New Radio (NR).

BACKGROUND

[0003] Machine-type communications (MTC) are widely used in many applications such as vehicle tracking, user and home security, banking, remote monitoring and smart grids. According to some reports, by 2023 there will be 3.5 billion wide-area devices connected to cellular networks. In this regard, Long Term Evolution - Machine Type Communication (LTE-M, LTE-MTC or eMTC) networks are being rolled out at a fast pace, and it is foreseen that in the next few years, a massive number of devices will be connected to the networks, addressing a wide spectrum of LTE-M use cases. Thanks to a design that enables 10-year battery lifetime of LTE-M devices, many of these devices will remain in service years after deployment. During the lifetime of these deployed LTE-M devices, many networks will undergo LTE to 5G New Radio (NR) migration. A smooth migration without causing service interruption to the deployed Internet-of-Things (IoT) devices is extremely important to mobile network operators (MNO). Furthermore, a migration solution that ensures superior radio resource utilization efficiency and superior coexistence performance between LTE-M and NR is highly desirable.

SUMMARY

[0004] Embodiments of the present invention provide for better coexistence of an LTE- M carrier inside an NR carrier. In general, if the LTE-M carrier can be placed in arbitrary places, this would satisfy its channel raster requirement. But this type of flexibility would require a guard band to be reserved within an NR carrier, around the LTE-M carrier, to prevent interference between the two systems. As a result, a significant number of NR resource blocks (RBs) might need to be reserved to accommodate the LTE-M carrier.

[0005] According to some embodiments, certain methodologies are used to determine the position where an LTE-M carrier will be placed within an NR carrier, to minimize interference between NR and LTE-M. To this end, the locations of LTE-M carrier center are identified that lead to subcarrier grid alignment between NR and LTE-M-ideally, a maximum amount of grid alignment. In addition, the possible locations of the LTE-M carrier center are identified such that a minimum number of NR resource blocks is used for accommodating the LTE-M carrier in the NR carrier. Further, the possible locations of the LTE-M carrier center are identified for which the maximum guard band can be used for LTE-M within a given number of NR RBs. Guard bands are dedicated spaces to prevent interference and are immediately adjacent to each end of the LTE-M carrier. In this case, the LTE-M guard bands fit entirely within the NR bandwidth. The maximum guard band may be the guard band amount at an LTE-M carrier center position (or positions) that is greater than the guard band amount that is available at other possible LTE-M carrier center grid-aligned positions. Transmission and reception are then carried out by network devices, while centering the LTE-M carrier in the NR bandwidth according to one of the identified possible locations for the LTE-M carrier center.

[0006] The embodiments described herein, using identified possible LTE-M carrier center locations, can be used to effectively deploy LTE-M in coexistence with NR in the case of, for example, 30 kHz NR subcarrier spacing. The approach addresses the problems of subcarrier grids alignment, interference (between NR and LTE-M) reduction, and resource utilization, which are the key issues in the coexistence of NR and LTE-M. When deploying LTE-M inside an NR carrier, this solution determines the best locations of LTE-M carrier center that leads to: 1) the maximum subcarrier grid alignment between NR and LTE-M thus minimizing the interference between these two systems, 2) the minimum reserved resources of NR RBs thus enhancing resource efficiency, and 3) the maximum potential guard band that can be considered for LTE-M within a given number of NR RBs. This, in turn, facilitates the coexistence of LTE-M with NR that in case of 30 kHz NR subcarrier spacing.

[0007] According to some embodiments, a method for communicating in a wireless communication network includes transmitting or receiving using an LTE-M carrier within the bandwidth of a NR carrier with guard bands that are immediately adjacent to each end of the LTE-M carrier and that fit entirely within the NR bandwidth. The center of the LTE-M carrier is aligned with an NR subcarrier on a 100 kHz NR raster grid, and wherein a maximum number of subcarriers in the LTE-M carrier align with subcarriers in NR. The center of the LTE-M carrier is located within the NR bandwidth such that: 1) a minimum number of NR resource blocks are occupied by any part of the LTE-M carrier and the guard bands at each end, given a predetermined bandwidth for each of the guard bands; and/or 2) given a predetermined number of NR resource blocks that can be occupied by any part of the LTE-M carrier and the guard bands at each end, a minimum guard band bandwidth from each end of the LTE-M carrier to the respective immediately adjacent NR resource block not occupied by any of part of the LTE-M carrier and the guard bands is maximized.

[0008] According to some embodiments, a network device, such as a wireless device or a radio network node, includes communication circuity and processing circuitry. The processing circuitry is configured to transmit or receive using an LTE-M carrier within the bandwidth of a NR carrier with guard bands that are immediately adjacent to each end of the LTE-M carrier and that fit entirely within the NR bandwidth. The center of the LTE-M carrier is aligned with an NR subcarrier on a 100 kHz NR raster grid, and where a maximum number of subcarriers in the LTE-M carrier align with subcarriers in NR. The center of the LTE-M carrier is located within the NR bandwidth such that: 1) a minimum number of NR resource blocks are occupied by any part of the LTE-M carrier and the guard bands at each end, given a predetermined bandwidth for each of the guard bands; and/or 2) given a predetermined number of NR resource blocks that can be occupied by any part of the LTE-M carrier and the guard bands at each end, a minimum guard band bandwidth from each end of the LTE-M carrier to the respective immediately adjacent NR resource block not occupied by any of part of the LTE-M carrier and the guard bands is maximized.

[0009] The techniques may also apply to LTE carriers more generally. According to some embodiments, a network device, such as a wireless device or a radio network node, includes communication circuity and processing circuitry. The processing circuitry is configured to transmit or receive using an LTE carrier within the bandwidth of a NR carrier with guard bands that are immediately adjacent to each end of the LTE carrier and that fit entirely within the NR bandwidth. The center of the LTE carrier is aligned with an NR subcarrier on a 100 kHz NR raster grid, and where a maximum number of subcarriers in the LTE carrier align with subcarriers in NR. The center of the LTE carrier is located within the NR bandwidth such that: 1) a minimum number of NR resource blocks are occupied by any part of the LTE carrier and the guard bands at each end, given a predetermined bandwidth for each of the guard bands; and/or 2) given a predetermined number of NR resource blocks that can be occupied by any part of the LTE carrier and the guard bands at each end, a minimum guard band bandwidth from each end of the FTE carrier to the respective immediately adjacent NR resource block not occupied by any of part of the FTE carrier and the guard bands is maximized.

[0010] Further aspects of the present invention are directed to an apparatus, network node, base station, wireless device, user equipment (UE), network devices, MTC devices, computer program products or computer readable storage medium corresponding to the methods summarized above and functional implementations of the above-summarized apparatus and UE.

[0011] Of course, the present invention is not limited to the above features and advantages. Those of ordinary skill in the art will recognize additional features and advantages upon reading the following detailed description, and upon viewing the accompanying drawings.

BRIEF DESCRIPTION OF THE FIGURES

[0012] FIG. 1 illustrates a frame structure in NR for 30 kHz subcarrier spacing.

[0013] FIG. 2 illustrates an example of NR raster location for 10 MHz channel bandwidth with 24 resource blocks (RBs) and 30 kHz subcarrier spacing, according to some embodiments.

[0014] FIG. 3 illustrates subcarrier grids for NR and FTE-M, according to some embodiments.

[0015] FIG. 4 illustrates subcarrier alignment in NR and FTE-M coexistence, according to some embodiments.

[0016] FIG. 5 illustrates a maximum subcarrier grid alignment between NR and FTE- M, according to some embodiments.

[0017] FIG. 6 illustrates maximum and minimum frequencies that need to be reserved for embedding FTE-M with guard band, according to some embodiments.

[0018] FIG. 7 illustrates the placing of FTE-M with guard band inside NR, according to some embodiments.

[0019] FIG. 8 illustrates resource block edges for an even number of NR resource blocks, according to some embodiments.

[0020] FIG. 9 illustrates resource block edges for an odd number of NR resource blocks, according to some embodiments.

[0021] FIG. 10 illustrates an FTE-M carrier with guard bands that overlaps four NR resource blocks, according to some embodiments.

[0022] FIG. 11 illustrates an LTE-M carrier with guard bands that overlaps five NR resource blocks, according to some embodiments.

[0023] FIG. 12 illustrates an LTE-M carrier inside q NR resource blocks, according to some embodiments.

[0024] FIG. 13 illustrates a flow diagram of a method that may be used by network devices, according to some embodiments.

[0025] FIG. 14 illustrates a block diagram of a network device that is a network node, according to some embodiments.

[0026] FIG. 15 illustrates is a block diagram of a network device that is a wireless device, according to some embodiments.

[0027] FIG. 16 schematically illustrates a telecommunication network connected via an intermediate network to a host computer, according to some embodiments.

[0028] FIG. 17 is a generalized block diagram of a host computer communicating via a base station with a user equipment over a partially wireless connection, according to some embodiments.

[0029] FIGS. 18, 19, 20, and 21 are flowcharts illustrating example methods implemented in a communication system including a host computer, a base station and a user equipment.

[0030] FIG. 22 is a block diagram illustrating a functional implementation of a network node, according to some embodiments.

[0031] FIG. 23 is a block diagram illustrating a functional implementation of a wireless device, according to some embodiments.

DETAILED DESCRIPTION

[0032] Exemplary embodiments of the present disclosure will now be described more fully hereinafter with reference to the accompanying drawings, in which examples of embodiments of inventive concepts are shown. Inventive concepts may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of present inventive concepts to those skilled in the art. It should also be noted that these embodiments are not mutually exclusive. Components from one embodiment can be tacitly assumed to be present/used in another embodiment. Any two or more embodiments described in this document may be combined with each other. The embodiments are described with respect to LTE-M and NR but can be adapted in other radio

access technologies (RATs) where the techniques or selections may be relevant. While the embodiments described herein involve LTE-M, these techniques and selected positions may also apply to LTE carriers more generally.

[0033] Embodiments described herein provide a method of network devices operating according to optimal positions of an LTE-M carrier within an 5G NR carrier (with, e.g., 30kHz subcarrier spacing) for which the interference between the two systems is minimized, while using the minimum number of NR RBs. In particular, the optimal positions of the LTE-M carrier center are identified for two key scenarios: 1) efficient placement of LTE-M inside NR given the required guard band for LTE-M (maximizing resource utilization); and 2) efficient placement of LTE-M inside NR given the number of NR RBs that can be reserved (interference mitigation by maximizing guard band).

[0034] Compared to LTE numerology where only one type of subcarrier spacing (15 kHz) is considered, NR supports different types of subcarrier spacing. Consequently, slot (or mini-slot in NR) length can be different between NR and LTE-M, depending on numerology. In various embodiments, the optimal coexistence of NR and LTE-M for 30 kHz NR subcarrier spacing is considered. For the case of 30 kHz NR subcarrier spacing, orthogonal OFDM symbol duration and subframe duration are shown in FIG. 1. In NR, frame, subframe, and slot are, respectively, 10 ms units, 1 ms units, and 14 OFDM symbols. Slot duration and number of slots in each subframe depends on the subcarrier spacing.

[0035] In LTE-M, the subcarrier spacing is 15 kHz. Therefore, full orthogonality between NR and LTE-M cannot be easily maintained in the case of 30 kHz NR subcarrier spacing. Nonetheless, it is possible to significantly reduce interference by maximizing the number of aligned subcarriers between NR and LTE-M. One LTE-M resource block includes 12 subcarriers, which is equivalent to a 180 kHz bandwidth. One NR resource block with 12 subcarriers and 30 kHz subcarrier spacing occupies a 360 kHz bandwidth. In this case, placing an LTE-M RB within an NR RB can enhance the resource efficiency, thus reducing overhead in the LTE-M and NR coexistence. The NR subcarrier spacing of 30 kHz (or higher) and the embodiments described herein may be beneficial to Ultra-Reliable Low-Latency Communication (URLLC) applications.

[0036] Table 1, shown below, lists frequency bands used by both NR and LTE-M and shows, for each band, the possible channel bandwidths for 30 kHz NR subcarrier spacing.

Table 1

[0037] Table 1 shows that the possible supported NR channel band widths for NR and

LTE-M coexistence may be: 10, 15, 20, 25, 30, 40, 50, 60, 80, and 100 MHz. Table 1 also lists the channel rasters that represent steps and frequencies that can be used by a UE to determine the radio frequency (RF) channel positions in the uplink and downlink. The channel raster of NR depends on the frequency band. An LTE-M UE searches for LTE-M carriers on a 100 kHz raster grid and, thus, a feasible center frequency for UE can be expressed as 100m, with m being an integer number. As we can see from Table 1, the channel raster step for the considered common bands for NR and LTE-M is 100 kHz.

[0038] There are several considerations to take into account. The raster defines a subset of RF reference frequencies that can be used to identify the RF channel position in the uplink and downlink. The RF reference frequency for an RF channel maps to a resource element on the carrier. Hereinafter, the channel raster is referred to as a point on the raster grid that defines the RF reference frequency. One NR RB in the frequency domain consists of 12 subcarriers. Note that an NR resource block is a one-dimensional measure spanning the frequency domain only, while an LTE PRB uses two-dimensional resource blocks of 12 subcarriers in the frequency domain and one slot in the time domain. The number of RBs is denoted by N RB. The indexes of the middle RB for even and odd numbers of RBs are, respectively, NRB/2 and (NRB -1)/2.

[0039] For NR carriers with an even number of RBs (NRB), the NR channel raster is located at subcarrier index #0 in an RB with index NRB/2. For NR carriers with an odd number

of RBs, the NR channel raster is located at subcarrier index #6 in an RB with index (NRB -1)/2. As an example, the pictorial representation of NR raster location for 10 MHz channel bandwidth with 24 RBs and 30 kHz subcarrier spacing is illustrated in FIG. 2.

[0040] Considering the fact that, in NR, the number of subcarriers is an even number, the carrier center is located between the two middle NR subcarriers. In this case, the NR carrier center frequency is related to the channel raster by:

FC = Fraster - 15 kHz (1) where Fc is the NR carrier center frequency and Fraster is the frequency where the NR channel raster is located. Clearly, Fc = — 15 kHz relative to the NR channel raster.

[0041] In LTE-M, there is a subcarrier in the center of the downlink system bandwidth called the DC subcarrier, which is an example of an even number of physical resource blocks (PRBs) within the LTE carrier. In this case, the LTE-M carrier center is placed on the DC subcarrier.

[0042] Now, one step is to find a condition under which the maximum alignment between NR and LTE-M downlink subcarrier grids is achieved. In one scenario, according to an embodiment, due to the different subcarrier spacing (i.e., 15 kHz LTE-M vs. 30 kHz NR) in NR and LTE-M systems, it is not possible to have a full subcarrier grid alignment between NR and LTE-M. Nevertheless, the optimal locations of an LTE-M carrier can be found such that the maximum subcarrier grid alignment is achieved in NR and LTE-M coexistence. As shown in FIG. 3, the maximum alignment between NR and LTE-M subcarrier grids is achieved when every two LTE-M subcarrier aligns with an NR subcarrier. That is, maximum alignment can occur when half of the LTE-M subcarriers align with the NR subcarriers.

Subcarrier orthogonality between NR and LTE-M

[0043] Let F1 and T1 be subcarrier spacing and symbol duration (excluding the cyclic prefix) of NR. Also, F2 and T2 are subcarrier spacing and symbol duration (excluding the cyclic prefix) of LTE-M. The relationships are expressed as:

Now, the orthogonality between NR and LTE-M subcarriers will be explored. Let an be an LTE-M modulated symbol on subcarrier n. The interference from subcarrier n of LTE-M on subcarrier m of NR is:

To ensure orthogonality and avoid intercarrier interference:

Clearly, the above condition can be satisfied when n is even. Therefore, the potential interference from LTE-M on NR is not completely eliminated when both use the same resources.

[0044] Let bm be an NR modulated symbol on subcarrier m. The interference from subcarrier m of NR on subcarrier n of LTE-M is:

To ensure orthogonality and avoid intercarrier interference:

n — 2m = integer.

The above condition can be always satisfied when n and m are integers. As a result, with the proposed subcarrier alignment scheme, the potential interference from NR on LTE-M is eliminated. Moreover, the proposed approach scientifically mitigates interference from LTE-M on NR by maximizing the number of aligned subcarriers between these two systems.

LTE-M carrier placement considering subcarrier grid alignment

[0045] In LTE-M, there is a subcarrier in the center of the downlink system bandwidth called the DC subcarrier, as shown in LIG. 4. In this case, the LTE-M carrier center is placed on the DC subcarrier.

[0046] Let k be an integer that represents the NR subcarrier index relative to the NR channel raster (i.e., NR carrier). The NR subcarriers are located at frequencies 100m + 30 k kHz (m is an integer). As shown in FIG. 5, an LTE-M carrier center (i.e., DC subcarrier) can be placed on two locations relative to an NR subcarrier with index k: 1) on subcarrier k of NR, and 2) 15 kHz higher than subcarrier k of NR. Therefore, an LTE-M carrier center can be placed on the following frequencies, relative to the NR raster: Case 1: 100m+30k, (kHz); Case 2: 100m+30k+15 (kHz). In addition, the location of the LTE-M carrier center must satisfy the raster offset requirement.

[0047] Considering the raster requirement, an LTE-M carrier center (which is on the

DC subcarrier) can be placed at 100n (kHz), where n is an integer. Hence, the feasible locations of an LTE-M carrier center, with respect to NR subcarrier k, should satisfy one of the following equations:

Case 1:

100n = 100m + 30k (2)

Case 2:

100n = 100m + 30k + 15. (3)

[0048] However, Case 2 is not feasible since the left side of equation (3) is even while the right side of the equation is odd. Therefore, only Case 1 is feasible for deploying LTE-M inside an NR carrier. In this case, the LTE-M carrier center is placed on an NR subcarrier.

[0049] Now, suppose k* is a solution to equation (2). Subsequently, the location of an

LTE-M carrier center can be identified based on the location of the NR subcarrier with index k*. Note that k can be index of any NR subcarrier while k* is the index of a desired subcarrier, which is considered for alignment. In this case, k* is in a set of all integer numbers generated by:

where r is an integer. For instance, for r = 3, using the LTE-M carrier center can be

placed on an NR subcarrier with index k* = 10 (relative to the channel raster). It can be shown that the LTE-M carrier center can be placed on NR subcarriers with indexes { ..., -20, -10, 0,10, 20, ... }, or equivalently k* = +10n, where n is integer (considering 30 kHz subcarrier spacing). The LTE-M carrier center can be placed on the following frequencies (relative to the NR channel raster):

FLTEM = 30k*[kHz] (5)

Table 2 shows possible NR subcarrier indices for the LTE-M carrier center, relative to the NR raster for 30 kHz subcarrier spacing. The possible locations of LTE-M carrier center are for which maximum subcarrier grid alignment may be achieved between NR and LTE-M.

Table 2

[0050] The proposed approach ensures the maximum subcarrier grids alignment for

NR and LTE-M. While this approach significantly mitigates potential interference between NR and LTE-M, some level of interference from LTE-M on NR may be observed when both use the same resources.

[0051] In order to further reduce any potential interference between LTE-M and NR systems, a guard band can be considered around the LTE-M carrier. Parameter G may be used to indicate the amount guard band used in each side of the LTE-M carrier when it is placed inside the NR carrier. FIG. 6 illustrates an LTE-M carrier with guard band.

[0052] In this case, the maximum and minimum possible values of k* depend on the

LTE-M and NR channel bandwidths as well as the guard band G used for LTE-M. According to FIG. 6, the maximum and minimum frequencies that need to be reserved for embedding LTE-M with guard band are, respectively,

(FLTEM + BL/2 + G ), and (FLTEM — BL/2 — G ).

To ensure that the LTE-M carrier with guard band is entirely placed in the NR carrier, the following conditions must be met:

(FLTEM + BL/2 + G) ≤ Fc + Bnr /2

(FLTEM BL/2 - G ) ≥ Fc - Bnr /2

where Bnr is the NR channel bandwidth and BL is the operational bandwidth for LTE-M (e.g., 1095 kHz). Considering equation (1), the feasible range of k* for deploying an LTE-M carrier inside the NR is:

In this example equation, the NR subcarrier spacing Ns is 30 kHz.

LTE-M placement inside NR given the required guard band

[0053] Possible locations of an LTE-M carrier center for which the maximum subcarrier grid alignment is achieved between NR and LTE-M was provided in Table 2. The location of the LTE-M carrier impacts the number of NR resource blocks that overlap with LTE-M resource blocks. In this scenario, it can be assumed that the amount of required guard band G between the LTE-M carrier and NR is given. FIG. 7 illustrates the placing of LTE-M with guard band inside NR.

[0054] One goal is to identify possible locations of the LTE-M carrier center inside an

NR carrier so as to occupy the minimum number of NR resource blocks. Among the LTE-M carrier center locations that ensure the maximum subcarrier grid alignment, those locations that lead to the minimum NR resource reservation are identified.

[0055] First, according to some embodiments, the edge frequencies of NR RBs (i.e., the minimum and maximum frequencies of each RB) are found relative to the NR channel raster. FIGS. 8 and 9 illustrate RB edges for even and odd numbers of NR resource blocks, respectively. For an even number of NR RBs, the minimum and maximum frequencies of the first RB, relative to the NR raster is:

Fmin = - 13 kHz

Fmax = Fmin+ 360 = 345 kHz

In this example, the NR RB bandwidth is 360 kHz, or 12 subcarriers at a spacing of 30 kHz.

Therefore, relative to the NR raster, the edge frequencies of RBs can be given by:

RB_edge_freq_even = -15 + 360L [kHz] (7) where L is an integer in set {- NRB/2+1,. . ., NRB/2+1 }, with N RB being the total number of NR RBs.

[0056] For an odd number of NR RBs, the minimum and maximum frequencies of the first RB, relative to the NR raster is:

Fmin = - 195 kHz

Fmax Fmin + 360 — 165 kHz

Therefore, relative to the NR raster, the edge frequencies of RBs can be given by:

RB_edge_freq_odd = -195 + 360L [kHz] (8) where L is an integer in set { -(NRB-1)/2, . . ., (NRB-1)/2+1 }, with N RB being the total number of NR RBs.

[0057] The minimum number of NR RBs that need to be used for deploying an LTE- M carrier is calculated by:

[0058] where [. ] is the ceiling function. In this case, N NR RBs must be used for LTE- M deployment. Note that in a non-optimal case, ( N + 1) NR RBs must be used. Next, the locations of the LTE-M carrier center are identified such that the minimum number of NR RBs (i.e., N) are occupied. The LTE-M carrier center frequency (relative to NR raster) may be:

FLTEM = 30k* [kHz] (10)

Subsequently, to ensure that the LTE-M resource block overlaps with only N NR RBs, the following applies. For an even number of NR RBs:

(-15 + 360L) + (BL/2 + G) ≤ FLTEM ≤ (-15 + 360(L + N )) - (BL/2 + G) where (—NRB/2 + 1) ≤ L ≤ NRB/2 is an integer. This leads to:

For an LTE-M carrier with 6 RBs and one DC subcarrier (in total 73 subcarriers), BL = 1095 [kHz]. For an odd number of NR RBs:

(-195 + 360L) + (BL/2 + G) ≤ FLTEM ≤ (-195 + 360(L + N )) - (BL/2 + G)

where -(NRB — 1)/2 ≤ L ≤ (NRB — 1)/2 is an integer. This leads to:

[0059] For example, for G = 100 kHz and a 10 MHz NR channel bandwidth (with 24 resource blocks), N and the range of k* for placing the LTE-M carrier center are computed.

Using (9), for an even number of NR resource blocks:

12L + 22 ≤ k* ≤ 12 L + 25 (14)

[0060] Considering Table 2, for instance k* = 10(10 = 12 X (-1) + 22) satisfies the condition in (14). Therefore, placing the LTE-M carrier center on FLTEM = 30 X 10 = 300 kHz relative to the NR raster, ensures maximum subcarrier grid alignment while overlapping with the minimum number of NR RBs. In this case, four NR RBs are used.

[0061] While for k * = 20 (according to Table 2) and the maximum subcarrier grid alignment between NR and LTE-M, five NR RBs must be used for deploying the LTE-M carrier. FIGS. 10 and 11 illustrate this example for k* = 10 and k * = 20. FIG. 10 illustrates an LTE-M carrier with guard band overlaps with four NR resource blocks ( k * = 10). FIG. 11 illustrates an LTE-M carrier with guard band overlaps with five NR resource blocks ( k * = 20).

[0062] In summary, the following steps may be used to find optimal locations of an

LTE-M carrier center for which the minimum number of NR RBs are used for deploying LTE-M carrier, according to some embodiments. First, find k * values that lead to the maximum subcarrier grids alignment between LTE-M and NR. Equations (4) and (6) can be used for this step. Second, compute the minimum number of NR RBs which need to be used for deploying an LTE-M carrier. Equation (9) can be used for this step. Third, for an even number of NR resource blocks, use equation (11) to find the range of k*. For an odd number of NR resource blocks, use equation (12) to find the range of k*. Fourth, the optimal values of k* can be found using the results of the first and third steps. Fifth, the optimal frequencies of an LTE-M carrier center, relative to the NR raster, are: FL TEM = 30 k* [kHz].

[0063] Note that for any given value of LTE-M guard band (i. e. , G), this approach can find the best positions of the LTE-M carrier center for which the minimum number of NR RBs is used for deploying the LTE-M carrier inside NR.

[0064] The NR raster may be located at subcarrier #0 in an RB with index NRB/2 for an even number of RBs. The NR raster may be located at subcarrier #6 in an RB with index (NRB- 1)/2 for an odd number of RBs. The subcarrier #0 corresponds to the lowest subcarrier in frequency in an RB and subcarrier index #11 corresponds to the highest subcarrier in frequency in an RB.

Examples with Known Guard Bands

[0065] In the following examples for two different guard bands (G = 100 kHz and 300 kHz), the optimal locations of an LTE-M carrier for various NR channel bandwidths are identified.

[0066] In the first example, G = 100 kHz, where there is 100 kHz of guard band on each side of the LTE-M carrier. With the proposed approach (optimal case), the minimum number of NR RBs used for deploying the LTE-M carrier is: N = 4. In a non-optimal case, N + 1 = 5 NR RBs are used. Therefore, this approach enhances the resource utilization by 20%.
CLAIMS

What is claimed is:

1. A network device, comprising:

transceiver circuitry; and

processing circuitry operatively associated with the transceiver circuitry and configured to:

transmit or receive, via the transceiver circuitry, using a Long Term Evolution - Machine Type Communication (LTE-M) carrier within the bandwidth of a New Radio (NR) carrier with guard bands that are immediately adjacent to each end of the LTE-M carrier and that fit entirely within the NR bandwidth,

wherein the center of the LTE-M carrier is aligned with an NR subcarrier on a 100 kHz NR raster grid, and wherein a maximum number of subcarriers in the LTE-M carrier align with subcarriers in NR, wherein the center of the LTE-M carrier is located within the NR bandwidth such that at least one of:

a minimum number of NR resource blocks are occupied by any part of the LTE-M carrier and the guard bands at each end, given a predetermined bandwidth for each of the guard bands; and given a predetermined number of NR resource blocks that can be occupied by any part of the LTE-M carrier and the guard bands at each end, a minimum guard band bandwidth from each end of the LTE-M carrier to the respective immediately adjacent NR resource block not occupied by any of part of the LTE-M carrier and the guard bands is maximized.

2. The network device of claim 1, wherein the center of the LTE-M carrier is positioned relative to an NR raster, considering 100 kHz guard band and 30 kHz NR subcarrier spacing, according to any offset position in the following table:

3. The network device of claim 1, wherein the center of the LTE-M carrier is positioned relative to an NR raster, considering 100 kHz guard band and 30 kHz NR subcarrier spacing, according to any offset position in the following table:

4. The network device of claim 1, wherein the center of the LTE-M carrier is positioned relative to an NR raster, considering 300 kHz guard band and 30 kHz NR subcarrier spacing, according to any offset position in the following table:

5. The network device of claim 1, wherein the center of the LTE-M carrier is positioned relative to an NR raster, considering 300 kHz guard band and 30 kHz NR subcarrier spacing, according to any offset position in the following table:

6. The network device of claim 1, wherein the center of the LTE-M carrier is positioned relative to an NR raster, considering 4 NR resource blocks and 30 kHz NR subcarrier spacing, according to any offset position in the following table:

7. The network device of claim 6, wherein the maximum guard band bandwidth is 157.5 kHz.

8. The network device of claim 1, wherein the center of the LTE-M carrier is positioned relative to an NR raster, considering 4 NR resource blocks and 30 kHz NR subcarrier spacing, according to any offset position in the following table:

9. The network device of claim 1, wherein the center of the LTE-M carrier is positioned relative to an NR raster, considering 5 NR resource blocks and 30 kHz NR subcarrier spacing, according to any offset position in the following table:

10. The network device of claim 9, wherein the maximum guard band bandwidth is 307.5 kHz.

11. The network device of claim 1, wherein the center of the LTE-M carrier is positioned relative to an NR raster, considering 5 NR resource blocks and 30 kHz NR subcarrier spacing, according to any offset position in the following table:

12. The network device of claim 1, wherein the center of the LTE-M carrier is located at an NR subcarrier index k* relative to an NR raster, where k is in a set k*=10q, where q is an integer,

wherein k* is in the range:

where Ns is NR subcarrier spacing, BL is operational bandwidth for LTE-M, Bnr is the NR bandwidth and G represents bandwidth of the guard bands for the LTE-M carrier,

wherein the LTE-M carrier center is positioned at k* according to one of the following equations, where N RB is the number of NR resource blocks (RBs):

for an even number of NR resource blocks, where L is an integer and

(-NRB/2 + 1) ≤ L ≤ NRB/2- and

for an odd number of NR resource blocks, where L is an integer and -(NRB — 1)/2 ≤ L ≤ (NRB - 1)/2.

13. The network device of claim 12, wherein the minimum number N of NR resource blocks needed for the LTE-M carrier is:

where
is a ceiling function.

14. The network device of claim 12,

wherein a minimum frequency Fnr,min = -15 + (12NS )L and a maximum frequency Fnr,max = — 15 + (12 NS )(L + NRB) for an even number of NR resource blocks, a minimum frequency Fnr,min = —15 — (12NS/2) + (12 NS )L and a maximum frequency Fnr,max = —15 — (12NS/2) + (12 NS )(L + NRB) for an odd number of NR resource blocks, and

wherein the maximum guard band bandwidth at left (lower frequency) and right (higher frequency) sides of the LTE-M carrier are Gright = Fnr,max —

( FLTEM + BL/2) and Gleft = (FLTEM - BL/2) - Fnr,min., where FLTEM is the LTE-M carrier center.

15. The network device of claim 14, wherein L is:

where
is the floor function, and

wherein the LTE-M carrier center FLTEM is in a position in the range of k* where L maximizes the Gleftt and the Gright.

16. The network device of claim 1, wherein NR and LTE-M subcarrier alignment occurs according to the equation: 100n = 100m + 30k, where 100m kHz represents the possible frequencies of an NR raster, considering 30 kHz NR subcarrier spacing, and 100n kHz represents where the LTE-M carrier center is able to be placed, where m and n are integers and k is an NR subcarrier index.

17. The network device of claim 1, wherein NR subcarrier spacing is 60 kHz.

18. The network device of claim 1, wherein an NR raster is located at subcarrier #0 in a resource block with index NRB/2 for an even number of resource blocks, wherein the NR raster is located at subcarrier #6 in a resource block with index (NRB-1)/2 for an odd number of resource blocks, wherein NRB is the number of resource blocks, and wherein subcarrier #0 corresponds to the lowest subcarrier in frequency in a resource block and subcarrier index #11 corresponds to the highest subcarrier in frequency in a resource block.

19. The network device of claim 1, wherein the network device is a wireless device.

20. The network device of claim 1, wherein the network device is a radio network node.

21. The network device of claim 1, wherein the processing circuitry is configured to generate a signal and transmit the generated signal on the LTE-M carrier within the bandwidth of the NR carrier.

22. The network device of claim 1, wherein the processing circuitry is configured to receive a signal on the LTE-M carrier within the bandwidth of the NR carrier and process the received signal.

23. The network device of claim 22, wherein the processing circuitry is configured to search for the LTE-M carrier within the bandwidth of the NR carrier according to an NR raster.

24. A method for communicating in a wireless communication network, comprising:

transmit or receive, via the transceiver circuitry, using a Long Term Evolution - Machine Type Communication (LTE-M) carrier within the bandwidth of a New Radio (NR) carrier with guard bands that are immediately adjacent to each end of the LTE-M carrier and that fit entirely within the NR bandwidth,

wherein the center of the LTE-M carrier is aligned with an NR subcarrier on a

100kHz NR raster grid, and wherein a maximum number of subcarriers in the LTE-M carrier align with subcarriers in NR,

wherein the center of the LTE-M carrier is located within the NR bandwidth such that at least one of:

a minimum number of NR resource blocks are occupied by any part of the

LTE-M carrier and the guard bands at each end, given a predetermined bandwidth for each of the guard bands; and

given a predetermined number of NR resource blocks that can be occupied by any part of the LTE-M carrier and the guard bands at each end, a minimum guard band bandwidth from each end of the LTE-M carrier to the respective immediately adjacent NR resource block not occupied by any of part of the LTE-M carrier and the guard bands at each end is maximized.

25. The method of claim 24, wherein the method further comprises generating a signal and the transmitting or receiving comprises transmitting the generated signal on the LTE-M carrier within the bandwidth of the NR carrier.

26. The method of claim 24, wherein the transmitting or receiving comprises receiving a signal on the LTE-M carrier within the bandwidth of the NR carrier and wherein the method further comprises processing the received signal.

27. A network device adapted to:

transmit or receive, via the transceiver circuitry, using a Long Term Evolution (LTE) carrier within the bandwidth of a New Radio (NR) carrier with guard bands that are immediately adjacent to each end of the LTE carrier and that fit entirely within the NR bandwidth,

wherein the center of the LTE carrier is aligned with an NR subcarrier on a 100 kHz NR raster grid, and wherein a maximum number of subcarriers in the LTE carrier align with subcarriers in NR,

wherein the center of the LTE carrier is located within the NR bandwidth such that at least one of:

a minimum number of NR resource blocks are occupied by any part of the LTE carrier and the guard bands at each end, given a predetermined bandwidth for each of the guard bands; and

given a predetermined number of NR resource blocks that can be occupied by any part of the LTE carrier and the guard bands at each end, a minimum guard band bandwidth from each end of the LTE carrier to the respective immediately adjacent NR resource block not occupied by any of part of the LTE carrier and the guard bands is maximized.