WO2019069168A1

WO2019069168A1 - Retransmission scheme for ofdm-index modulation and spatial modulation

Info

Publication number: WO2019069168A1
Application number: PCT/IB2018/057265
Authority: WO
Inventors: Akram Bin Sediq; Ali AFANA; Salama Ikki; Alex Stephenne
Original assignee: Telefonaktiebolaget Lm Ericsson (Publ)
Priority date: 2017-10-04
Filing date: 2018-09-20
Publication date: 2019-04-11

Abstract

According to certain embodiments, a method in a transmitter includes transmitting, in a first time slot, a first transmission according to a first mapping of bits to indices and transmitting, in a second time slot, a second transmission according to a second mapping of bits to indices. The second mapping of bits to indices is a re-arrangement of and varies from the first mapping of bits to indices.

Description

RETRANSMISSION SCHEME FOR OFDM-INDEX MODULATION AND SPATIAL MODULATION

TECHNICAL FIELD

Certain embodiments of the present disclosure relate, in general, to wireless communications and more particularly to a retransmission scheme for OFDM-Index Modulation and Spatial Modulation.

BACKGROUND

Spatial Modulation (SM), which has been proposed for Multiple-Input Multiple- Output (MFMO) systems, is a promising technique that utilizes the spatial information to boost spectral efficiency. At each time instance, only a single transmit antenna is activated among the set of existing transmit antennas whereby the activated antenna index is implicitly used to convey information in addition to the well-known M-ary modulation schemes.

As compared to classical MFMO techniques, SM is shown to have several advantages, which may include complete avoidance of inter-channel interference (ICI), relaxed inter- antenna synchronization requirements, low receiver complexity, and use of a single RF chain at the transceiver.

The concept may be readapted to Orthogonal Frequency Division Multiplexing (OFDM) systems by referring to subcarriers indices as antenna indices. Motivated by the advantages of the Spatial Modulation (SM), recent studies have introduced the OFDM with Index Modulation (OFDM-IM), where according to the index selection bits, only a subset of available subcarriers are selected as active, while the remaining inactive subcarriers are not used and set to zero. Hence the specific legitimate combination of the subcarrier i ndices of the activated subcarriers carry implicit information. Recent performance investigations identify the beneficial operating region of the FM scheme over its conventional OFDM counterpart, hence providing general design guidelines for the HVI parameters. More specifically, an IM scheme is shown to be beneficial for the scenario of a relatively low transmission rate below 2 b/s/Hz.

A similar idea is called subcarrier index modulation OFDM (SFM-OFDM), in which half of the subcarriers are activated based on the incoming information bits and remaining subcarriers are assigned to control signaling. See, R A. Alhiga and H. Haas, "Subcarrier-index modulation OFDM," in Proc. IEEE 20th Int. Symp. on Personal, Indoor and Mobile Radio Commun. (PFMRC), Tokyo, Japan, Sept. 2009, pp. 177-181. To solve the resulting error propagation problem in SFM-OFDM, an enhanced SEVIOFDM scheme was later introduced, which uses one bit to control two adjacent subcarriers such that only one subcarrier is activated at each time instant. See, D. Tsonev, S. Sinanovic, and H. Haas, "Enhanced subcarrier index modulation (SIM) OFDM," in Proc. IEEE Global Commun. Conf. (GLOBECOM) Workshops, Houston, TX, USA, Dec. 201 1, pp. 728-732. The restriction on the number of active subcarriers is relaxed in a new technique known as OFDM-EVI. See, E. Basar, U. Aygolu, E. Panayirci, and H. V. Poor, "Orthogonal frequency division multiplexing with index modulation," IEEE Trans. Signal Process., vol. 61, no. 22, pp. 5536-5549, Nov. 2013.

OFDM-EVI has received considerable attention from the research community and industry. Similar to classical OFDM, OFDM-FM exhibits a single-symbol decoding complexity when employing the log-likelihood ratio (LLR) or low-complexity maximum-likelihood (ML) detection. See, B. Zheng, F. Chen, M. Wen, F. Ji, H. Yu, and Y. Liu, "Low complexity ML detector and performance analysis for OFDM with in-phase/quadrature index modulation," IEEE Commun. Lett, vol. 19, no. 11, pp. 1893-1896, Nov. 2015. Performance comparison with classical OFDM has been made in the literature for both uncoded and coded systems, where the results show that OFDM-FM offers lower bit error rate (BER), higher achievable rate, and higher efficiency. See, M. Wen, X. Cheng, M. Ma, B. Jiao, and H. V. Poor, "On the achievable rate of OFDM with index modulation," IEEE Trans. Signal Process., vol. 64, no. 8, pp. 1919-1932, Apr. 2016. See also, N. Ishikawa, S. Sugiura, and L. Hanzo, "Subcarrier- index modulation aided OFDM - will it work?," IEEE Access, vol. 4, pp. 2580-2593, 2016. Moreover, since only a set of subcarriers are active, OFDM-IM has the potential to suppress the inter-carrier interference, which is a common problem in OFDM systems. See, Q. Ma, P. Yang, Y. Xiao, H. Bai, and S. Li, "Error probability analysis of OFDM-FM with carrier frequency offset," IEEE Commun. Lett., vol. 20, no. 12, pp. 2434-2437, Dec. 2016.

Similar to the case of SM, spectral efficiency (SE) and diversity issues exist in OFDM- IM. So far, significant work has been done to investigate the SE issue. For example, OFDM with generalized index modulation (OFDM-GIM) has been introduced, where the number of active subcarriers is variable. See, R. Fan, Y. J. Yu, and Y. L. Guan, "Generalization of orthogonal frequency division multiplexing with index modulation," IEEE Trans. Wireless Commun., vol. 14, no. 10, pp. 5350-5359, Oct. 2015. Motivated by the principle of quadrature SM, OFDM with in-phase/quadrature index modulation (OFDMIQ-IM) is proposed, which applies OFDM-FM on the I and Q-components independently, doubling the number of EV1 bits. Moreover, it is shown that under an SE of 2 bps/Hz, OFDM-IQ-FM offers more than 6dB and 3dB signal-to-noise ratio (SNR) gains over classical OFDM and OFDM- IM, respectively.

Unlike the aforementioned two schemes, which rely on the extension of the index domain, the recently-new dual-mode index modulation aided OFDM (DM-OFDM) enhances the SE by increasing the number of modulation bits. See, T. Mao, Z. Wang, Q. Wang, S. Chen, and L. Hanzo, "Dual-mode index modulation aided OFDM," IEEE Access, vol. 5, pp. 50-60, 2017. Additionally, a direct combination of OFDM-FM with MFMO transmission techniques, which is called MFMO-OFDM-FM, is introduced to linearly increase the SE. See, E. Basar, "Multiple-input multiple-output OFDM with index modulation," IEEE Signal Process. Lett., vol. 22, no. 12, pp. 2259-2263, Dec. 2015. On the other hand, generalized space-and- frequency index modulation (GSFFM) improves the SE by activating a set of transmit antennas according to partial information bits and selecting the active space -frequency elements at the active transmit antennas according to the remaining information bits. See, T. Datta, H. S. Eshwaraiah, and A. Chockalingam, "Generalized space and-frequency index modulation," IEEE Trans. Veh. Technol., vol. 65, no. 1, pp. 4911-4924, Jul. 2016. On the other side, various ways have been used to investigate the diversity issue. Instead of localized subcarrier grouping, the interleaved based version is introduced for OFDM-FM to obtain frequency diversity. See, M. Wen, X. Cheng, M. Ma, B. Jiao, and H. V. Poor, "On the achievable rate of OFDM with index modulation," IEEE Trans. Signal Process., vol. 64, no. 8, pp. 1919-1932, Apr. 2016. See also, Y. Xiao, S. Wang, L. Dan, X. Lei, P. Yang, and W. Xiang, "OFDM with interleaved subcarrier-index modulation," IEEE Commun. Lett., vol. 18, no. 8, pp. 1447-1450, Aug. 2014. See also, X. Cheng, M. Wen, L. Yang, and Y. Li, "Index modulated OFDM with interleaved grouping for V2X communications," in Proc. IEEE Int. Conf. Intell. Transport. Syst. (ITSC), Qingdao, China, Oct. 2014, pp. 1097-4104.

However, a common assumption of all aforementioned techniques is that they use only a single transmission scheme for transmissions and retransmissions.

SUMMARY

Certain embodiments described herein address the problems of previous techniques by using a re-arrangement of the subcarrier indices and/or modulated symbols or variable bit/indices assignment in case of re-transmission. According to certain embodiments, a method in a transmitter includes transmitting, in a first time slot, a first transmission according to a first mapping of bits to indices and transmitting, in a second time slot, a second transmission according to a second mapping of bits to indices. The second mapping of bits to indices is a re-arrangement of and varies from the first mapping of bits to indices.

According to certain embodiments, a transmitter includes a memory storing instructions and processing circuitry operable to execute the instructions to cause the transmitter to transmit, in a first time slot, a first transmission according to a first mapping of bits to indices and transmit, in a second time slot, a second transmission according to a second mapping of bits to indices. The second mapping of bits to indices is a re-arrangement of and varies from the first mapping of bits to indices.

According to certain embodiments, a method in a receiver includes receiving, in a first time slot, a first transmission according to a first mapping of bits to indices and receiving, in a second time slot, a second transmission according to a second mapping of bits to indices. The second mapping of bits to indices is a re-arrangement of and varies from the first mapping of bits to indices.

According to certain embodiments, a receiver includes a memory storing instructions and processing circuitry operable to execute the instructions to cause the receiver to receive, in a first time slot, a first transmission according to a first mapping of bits to indices and receive, in a second time slot, a second transmission according to a second mapping of bits to indices. The second mapping of bits to indices is a re-arrangement of and varies from the first mapping of bits to indices.

Embodiments of the present disclosure may provide one or more technical advantages. As an example, a technical advantage may be that certain embodiments improve the performance of OFDM-IM by allowing a mapping between bits and OFDM-IM subblocks to vary between retransmissions. As another example, a technical advantage may be that certain embodiments propose a retransmission scheme of OFDM-ΓΜ with indices rearrangement that, under fair comparison, enhances the overall BER performance significantly at the receiver side compared to the case of retransmission without rearrangement schemes. For example, at uncoded BER of 10^~3, certain embodiments may lead to a gain of about 3 dB when 16-QAM is used and 3.9 dB when 64-QAM is used.

As another example, a technical advantage of certain embodiments may be that, since OFDM-FM is motivated by spatial modulation, the proposed retransmission scheme is very applicable and beneficial to the spatial modulation. As still another example, a technical advantage of certain embodiments may be that varying the lookup assignment table between indices and modulated symbols in the retransmission scheme improves the BER performance compared to the same lookup table in the retransmission scheme.

Certain embodiments may include none, some, or all of these advantages. Certain embodiments may include other advantages, as would be understood by a person having ordinary skill in the art.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGURE 1 illustrates an example OFDM-EVI transmitter, according to certain embodiments.

FIGURE 2 illustrates a look-up table, according to a particular example embodiment.

FIGURE 3 illustrates a graph depicting Bit Error Rate versus signal to noise ratio for a retransmission scheme with/out indices rearrangement with 16 -QAM, according to a particular embodiment.

FIGURE 4 illustrates a graph depicting Bit Error Rate vs. SNR for a retransmission scheme with/out indices rearrangement with 64-QAM, according to a particular embodiment

FIGURE 5 illustrates an example embodiment of a network for implementing a retransmission scheme for improved BER performance in a transmitter and receiver, in accordance with certain embodiments.

FIGURE 6 illustrates an exemplary wireless device, in accordance with certain embodiments.

FIGURE 7 illustrates an exemplary network node, in accordance with certain embodiments.

FIGURE 8 illustrates an exemplary radio network controller or core network node, in accordance with certain embodiments.

FIGURE 9 illustrates an example method for improved BER performance in a transmitter, according to certain embodiments.

FIGURE 10 illustrates an example virtual computing device for improved BER performance, according to certain embodiments.

FIGURE 1 1 illustrates another example method in a transmitter, according to certain embodiments.

FIGURE 12 illustrates another example virtual computing device, according to certain embodiments

FIGURE 13 illustrates an example method for improved BER performance in a receiver, according to certain embodiments. FIGURE 14 illustrates an example virtual computing device for improved BER performance in a receiver, according to certain embodiments.

FIGURE 15 illustrates another example method in a receiver, according to certain embodiments.

FIGURE 16 illustrates an example virtual computing device, according to certain embodiments.

DETAILED DESCRIPTION

According to certain embodiments, Orthogonal Frequency Division Multiplexing with Index Modulation (OFDM-DVI) conveys information bits through both the subcarrier activation patterns and the amplitude phase modulation constellation points. A retransmission with indices rearrangement scheme in OFDM-FM systems is proposed herein to enhance the overall Bit error rate (BER) performance. According to a particular embodiment, an exhaustive search is performed for possible optimal bits rearrangement in the second time- slot that offers the best performance. In addition, this invention presents a retransmission scheme with a variable lookup table mapping bits and indices (n,k) to improve the BER performance. As used herein, n is the sublock size of available sucarriers and A: is the number of activated subcarriers. In this mapping method, a look-up table of certain size is created to use at both transmitter and receiver sides in the first time-slot and a different (n,k) is used in the second time-slot for the same size. At the transmitter, the look-up table provides the corresponding indices for the incoming bits for each subblock, and the operation is reversed at the receiver.

According to certain embodiments, the performance of OFDM-FM is improved by allowing a mapping between bits and OFDM-IM subblocks to vary between retransmissions. By carefully designing the mapping in retransmissions, the BER performance may be significantly improved. According to particular embodiments, for example, the mapping may be varied using a rearrangement of bits. For example, the bits in subsequent transmissions may be reassigned such that the bits that are transmitted in the previous transmission using M-ary modulation are retransmitted using subcarrier indices and vice versa. Such re-assignment can provide better averaging of the reliability of the bits. In a particular embodiment, an exhaustive search may be used in an offline manner to find the bit re-assignment that provides the minimum BER.

According to other particular embodiments, the mapping may be varied by varying the subblock size, n, and/or the number of subcarriers that are used for transmissions, k. Unlike the previous approach, this approach changes n and/or k, in subsequent transmissions, while keeping the spectral efficiency, pin (bit/sec/subcarrier) the same for all transmissions to ensure that all transmissions carry the same number of bits, assuming the total number of subcarriers does not change.

While certain embodiments are mainly presented in the context of OFDM-FM for two transmissions, those skilled in the art will appreciate that the techniques are also applicable to generalized space-and-frequency index modulation (GSFFM), with OFDM-HVI and spatial modulation as special cases. Thus, the indices discussed above may include antenna indices or subcarrier indices, in various embodiments. Further, though first and second transmissions may be described in certain example embodiments, the techniques are applicable to an arbitrary number of transmissions.

FIGURE 1 illustrates an example OFDM-EVI transmitter 100, according to certain embodiments. Consider OFDM block generating parallel data streams over N OFDM subcarriers from a given m bits stream. These m bits are not only used to symbol mapping like in the case of standard OFDM, but for both index subcarriers and symbol modulation.

According to certain embodiments, the sequence of the m bit is spilled into G groups, each group is composed of p bits, i.e., m=pG. Inspired by SM modulation, each OFDM subblock of n subcarriers where n =NIG, carries p\ bits through index modulation by activating only k out of n subcarriers and carries p2 bits through M-ary signal constellation independently for the quadrature dimension, where p =pl + p2, pl = log2(C(«; k)), where C{n, k) returns the number of possible subcarrier activations and it is assumed to be a power of two, and p2 = k log2( ).

The active k subcarriers indices, as described herein, are provided from a look-up table. FIGURE 2 illustrates a look-up table 200, according to a particular example embodiment, where it is assumed that =16 (e.g., 16-QAM), n=4, and k=2. In this example, pl= 2 bits, ?2 = 2*4 = 8 bit, and p = p\+p2 = 10 bits. To transmit the 10-bits [0, 1, 0, 0, 0, 0, 1, 0, 1, 0], the first two bits [0, 1] will be conveyed by only transmitting in the second and the third subcarrier and not transmitting anything in the first and fourth subcarrier, as shown in FIGURE 2. The rest of the bits will be transmitted using two 16-ary constellations, i.e., [0, 0, 0, 0] will be mapped to a 16-ary symbol and gets transmitted in the second subcarrier, and [1,0, 1,0] will be mapped to a 16-ary symbol and gets transmitted in the third subcarrier.

The joined G complex subblocks lead to the OFDM block of length N. By applying an Inverse Fast Fourier Transform (IFFT), the symbol vectors are turned into the time domain. To avoid inter-symbol interference (ISI) in addition to the intercarrier interference (ICI), a cyclic prefix (CP) is added before the transmission of each symbol.

According to certain embodiments, at the receiver antenna, CP is removed from the signal vector and Fast Fourier Transform (FFT) is applied. The receiver is aware of the lookup table used to construct OFDM-EVl symbols, thus it can demodulate the transmitted OFDM- EV1 symbols. Without loss of generality, it may be assumed that the receiver uses Maximum likelihood detection for demodulation. Thus, the techniques presented herein are applicable to any receiver structure.

Consider also the retransmission of the same information. Retransmission may happen if the first transmission is lost or not decoded correctly by the receiver, using, for example, Hybrid Automatic Repeat Request (HARQ). Retransmission may also happen in cooperative relaying where a relay is used to retransmit the same information from the source to the destination. In a particular embodiment, the retransmission may comprise a chase-combining type of retransmission, where the same identical information is retransmitted. The techniques may additionally be applicable to incremental redundancy, according to particular embodiments.

According to certain embodiments, the following assumptions are made:

• The channels between the transmitter and the receiver for the original and all retransmissions are independent and identically distributed channels.

• The receiver uses a single receive antenna. However, the techniques may be extended to the case of multi receive antenna.

• The receiver stores the soft symbols of the original transmission and subsequent retransmissions.

• The receiver uses joint maximum likelihood detection, which relies on all soft symbols of the original transmission and all retransmissions. For instance, assuming the received soft symbol vector r_f in the z^'th transmission, i E [0, nrofReTxs] is given by:

r_£ = HiSiib) + tii,

where H_f is a complex n x n diagonal channel matrix in the z^'th transmission, s^b) is a mapping function that maps p bits into a complex vector of size n representing the OFDM-FM subblock transmitted in the ith transmission, and n_£ is a complex vector of size n represent complex Gaussian noise. Under these assumptions, the maximum likelihood detector in this case can be expressed as:

nrofReTxs

In conventional OFDM-EVI scheme, the same mapping is assumed to be used to map bits to OFDM-EVI subblocks in all retransmissions, i.e., s^b) = S_j(b), where i≠ j. According to certain embodiments, however, this assumption is relaxed and the mapping between bits and OFDM-EVI subblocks is allowed to vary between retransmissions. By carefully designing the mapping in retransmissions, BER performance may be significantly improved.

According to certain embodiments, the mapping may vary by using a rearrangement of bits. It may be noted that the bits that are conveyed using M-ary modulations may be more prone to errors as compared to the bits that are conveyed using subcarrier indices. This is because correct demodulation of M-ary symbols is dependent on identifying the correct indices of OFDM subcarriers that are used for transmitting the M-ary symbols. Thus, if the bits that are conveyed using subcarrier indices are not decoded correctly, the bits that are conveyed using M-ary symbols will most likely not be decoded correctly. Note that the opposite is not true.

Using this insight, the bits in subsequent transmissions may be reassigned such that the bits that are transmitted in the previous transmission using M-ary modulation are retransmitted using subcarrier indices and vice versa. Such re-assignment can provide better averaging of the reliability of the bits. In a particular embodiment, an exhaustive search in an offline manner is used to find the bit re-assignment that provides the minimum BER. For example, the re-assignments found through an exhaustive search for n=4, k=2, and for both =16-QAM and M=64-QAM are summarized below in Tables 1 and 2:

Table 1 : Rearrangement of bits when n=A, k=2, and M=

Exhaustive Search b l3 b l l b8 b7 bO b2 b4 b5 b lO b9 bl bl2 b3 b6

Table 2: Rearrangement of bits when n=4, k=2, and = 64

According to certain other embodiments, the mapping may vary by varying the subblock size, n, and/or the number of subcarriers that are used for transmissions, k. Unlike the previous approach, this approach changes n and/or k in subsequent transmissions, while keeping the spectral efficiency, pin (bit/sec/subcarrier) of a retransmission to be equal or larger than the previous transmission, to ensure that a retransmission can carry all bits in the previous transmissions, assuming the total number of subcarriers does not change. For example, if n=4, k=2, M=\ 6 m^' one transmission (p=p\+p2=2 bits + 8 bits = 10 bits, pln= 10/4= 2.5 bit/sec/subcarrier), then in subsequent transmission we can use n=4, k=3, M=8 (p=p\+p2=\ bit + 9 bits = 10 bits, pln=\ OI4= 2.5 bit/sec/subcarrier). Moreover, in another subsequent transmission, we can use n=6, k=4, =8 (p=p\+p2=3 bits+12 bits=15 bits, pln=\ 5l 6=2.5 bits/sec/ subcarrier) .

According to certain embodiments, it may be possible to have the spectral efficiency of a retransmission larger than the previous transmission. In such a case, a retransmission will carry more bits than the previous transmission. Padding may be used to fill the extra empty bits that will be transmitted in the retransmission.

The embodiments described herein use rearrangement scheme in OFDM-EVI by reassigning the bits in subsequent retransmissions that are conveyed by the subcarrier indices and M-ary modulations and to vary the subblock size and/or the number of subcarriers that are used for subsequent retransmissions.

The BER performance of the OFDM-EVI scheme was evaluated via Monte Carlo simulations. The error performance of OFDM-IM was investigated under ideal and realistic channel conditions. In all simulations, the following system parameters were assumed: frequency-selective Rayleigh fading channel,

Carrier frequency: 2 GHz,

Bandwidth: 20 MHz,

Sub-carrier spacing: 15 kHz,

Length of cyclic prefix (L): 32,

N= 128 subcarriers,

Channel Estimation: Ideal with ML detection and n = 4, k = 2 for each subblock. The spectral efficiency of the considered schemes is given by m=(N +V) bits/s/Hz, where m is the number of bits transmitted per OFDM block as mentioned before. The SNR is defined as EbINO, where Eb = m=(N+L) is the average transmitted energy per bit and NO is the noise variance in the time domain. The following four schemes were simulated under fair comparison of same power and spectral efficiency:

• Classical OFDM with single transmission

• OFDM-IM with single transmission

• OFDM-EVI with two transmissions without any rearrangement, i.e., the same signal will be transmitted in both transmissions.

• OFDM-EVI with two transmissions with the rearrangement found through

exhaustive search (a proposed invention), where the first transmission is the same as conventional OFDM-IM transmission and the second transmission is obtained by rearranging the bits in the second transmission.

The total transmit power was kept the same for all four schemes.

FIGURE 3 illustrates a graph 300 depicting Bit Error Rate vs. SNR for a retransmission scheme with/out indices rearrangement with 16-QAM, according to a particular embodiment. Specifically, the BER performance of all four schemes is plotted, where 16-QAM is used for the M-ary symbols in OFDM-ΓΜ subblocks. By comparing classical OFDM with OFDM-EVI with single transmission, good gain was observed to motivate the use of OFDM-EVI. By comparing OFDM-EVI with two transmissions without any rearrangement and rearrangement as proposed herein, a substantial gain of around 3 dB at BER=10^"3 was realized.

FIGURE 4 illustrates a graph 350 depicting Bit Error Rate vs. SNR for a retransmission scheme with/out indices rearrangement with 64-QAM, according to a particular embodiment. Specifically, the BER performance of all four schemes is plotted, where 64-QAM is used for the M-ary symbols in OFDM-EVI subblocks. By comparing classical OFDM with OFDM-EVI with single transmission, good gain was observed to motivate the use of OFDM-EVI. By comparing OFDM-EVI with two transmissions without any rearrangement and the proposed invention, a substantial gain of around 3.9 dB at BER=10^"3 was realized.

FIGURE 5 illustrates an example embodiment of a network 400 for implementing a retransmission scheme for improved BER performance in a transmitter and receiver, in accordance with certain embodiments. Network 400 includes one or more UE(s) 410 (which may be interchangeably referred to as wireless devices 410) and one or more network node(s) 415 (which may be interchangeably referred to as gNBs 415). UEs 410 may communicate with network nodes 415 over a wireless interface. For example, a UE 410 may transmit wireless signals to one or more of network nodes 415, and/or receive wireless signals from one or more of network nodes 415. The wireless signals may contain voice traffic, data traffic, control signals, and/or any other suitable information. In some embodiments, an area of wireless signal coverage associated with a network node 415 may be referred to as a cell 425. In some embodiments, UEs 410 may have device-to-device (D2D) capability. Thus, UEs 410 may be able to receive signals from and/or transmit signals directly to another UE.

In certain embodiments, network nodes 415 may interface with a radio network controller. The radio network controller may control network nodes 415 and may provide certain radio resource management functions, mobility management functions, and/or other suitable functions. In certain embodiments, the functions of the radio network controller may be included in network node 415. The radio network controller may interface with a core network node. In certain embodiments, the radio network controller may interface with the core network node via an interconnecting network 420. Interconnecting network 420 may refer to any interconnecting system capable of transmitting audio, video, signals, data, messages, or any combination of the preceding. Interconnecting network 420 may include all or a portion of a public switched telephone network (PSTN), a public or private data network, a local area network (LAN), a metropolitan area network (MAN), a wide area network (WAN), a local, regional, or global communication or computer network such as the Internet, a wireline or wireless network, an enterprise intranet, or any other suitable communication link, including combinations thereof.

In some embodiments, the core network node may manage the establishment of communication sessions and various other functionalities for UEs 410. UEs 410 may exchange certain signals with the core network node using the non-access stratum (NAS) layer. In non-access stratum signaling, signals between UEs 410 and the core network node may be transparently passed through the radio access network. In certain embodiments, network nodes 415 may interface with one or more network nodes over an internode interface.

As described above, example embodiments of network 400 may include one or more wireless devices 410, and one or more different types of network nodes capable of communicating (directly or indirectly) with wireless devices 410.

In some embodiments, the non-limiting term UE is used. UEs 410 described herein can be any type of wireless device capable of communicating with network nodes 415 or another UE over radio signals. UE 410 may also be a radio communication device, target device, D2D UE, NB-IoT device, MTC UE or UE capable of machine-to-machine communication (M2M), low-cost and/or low-complexity UE, a sensor equipped with UE, Tablet, mobile terminals, smart phone, laptop embedded equipped (LEE), laptop mounted equipment (LME), USB dongles, Customer Premises Equipment (CPE), etc.

Also, in some embodiments, generic terminology "radio network node" (or simply "network node") is used. It can be any kind of network node, which may comprise a gNB, base station (BS), radio base station, Node B, base station (BS), multi -standard radio (MSR) radio node such as MSR BS, evolved Node B (eNB), network controller, radio network controller (RNC), base station controller (BSC), relay node, relay donor node controlling relay, base transceiver station (BTS), access point (AP), radio access point, transmission points, transmission nodes, Remote Radio Unit (RRU), Remote Radio Head (RRH), nodes in distributed antenna system (DAS), Multi -cell/multicast Coordination Entity (MCE), core network node (e.g., MSC, MME, etc.), O&M, OSS, SON, positioning node (e.g., E-SMLC), MDT, or any other suitable network node.

The terminology such as network node and UE should be considered non -limiting and, in particular, does not imply a certain hierarchical relation between the two; in general, "eNodeB" could be considered as device 1 and "UE" device 2, and these two devices communicate with each other over some radio channel.

Example embodiments of UE 410, network nodes 415, and other network nodes (such as radio network controller or core network node) are described in more detail below with respect to FIGURES 6-12.

Although FIGURE 5 illustrates a particular arrangement of network 400, the present disclosure contemplates that the various embodiments described herein may be applied to a variety of networks having any suitable configuration. For example, network 400 may include any suitable number of UEs 410 and network nodes 415, as well as any additional elements suitable to support communication between UEs or between a UE and another communication device (such as a landline telephone). Furthermore, although certain embodiments may be described as implemented in an NR or 5G network, the embodiments may be implemented in any appropriate type of telecommunication system supporting any suitable communication and using any suitable components, and are applicable to any radio access technology (RAT) or multi-RAT systems in which a UE receives and/or transmits signals (e.g., data). For example, the various embodiments described herein may be applicable to IoT, NB-IoT, LTE, LTE-Advanced, UMTS, HSPA, GSM, cdma2000, WCDMA, WiMax, UMB, WiFi, another suitable radio access technology, or any suitable combination of one or more radio access technologies.

FIGURE 6 is a block schematic of an exemplary wireless device 410 for improved BER performance, in accordance with certain embodiments. Wireless device 410 may refer to any type of wireless device communicating with a node and/or with another wireless device in a cellular or mobile communication system. Examples of wireless device 410 include a mobile phone, a smart phone, a PDA (Personal Digital Assistant), a portable computer (e.g., laptop, tablet), a sensor, a modem, an MTC device / machine -to-machine (M2M) device, laptop embedded equipment (LEE), laptop mounted equipment (LME), USB dongles, a D2D capable device, or another device that can provide wireless communication. A wireless device 410 may also be referred to as UE, a station (STA), a device, or a terminal in some embodiments. Wireless device 410 includes transceiver 510, processing circuitry 520, and memory 530. In some embodiments, transceiver 510 facilitates transmitting wireless signals to and receiving wireless signals from network node 415 (e g , via antenna 540), processing circuitry 520 (e.g., which may include one or more processors) executes instructions to provide some or all of the functionality described above as being provided by wireless device 410, and memory 530 stores the instructions executed by processing circuitry 520.

Processing circuitry 520 may include any suitable combination of hardware and software implemented in one or more modules to execute instructions and manipulate data to perform some or all of the described functions of wireless device 410, such as the functions of UE 410 (i.e., wireless device 410) described in relation to any of sections 3, 4, and 6 herein. For example, in general, processing circuitry may save a current version of system information and/or apply a previously stored version of system information based on a system information notification (e.g., system information change notification, system information modification, or system information update) received in a paging message from a network node 415. In some embodiments, processing circuitry 520 may include, for example, one or more computers, one or more central processing units (CPUs), one or more microprocessors, one or more applications, one or more application specific integrated circuits (ASICs), one or more field programmable gate arrays (FPGAs) and/or other logic.

Memory 530 is generally operable to store instructions, such as a computer program, software, an application including one or more of logic, rules, algorithms, code, tables, etc. and/or other instructions capable of being executed by a processor. Examples of memory 530 include computer memory (for example, Random Access Memory (RAM) or Read Only Memory (ROM)), mass storage media (for example, a hard disk), removable storage media (for example, a Compact Disk (CD) or a Digital Video Disk (DVD)), and/or or any other volatile or non-volatile, non-transitory computer-readable and/or computer-executable memory devices that store information, data, and/or instructions that may be used by processor 520.

Other embodiments of wireless device 410 may optionally include additional components beyond those shown in FIGURE 6 that may be responsible for providing certain aspects of the wireless device's functionality, including any of the functionality described above and/or any additional functionality (including any functionality necessary to support the solution described above). As just one example, wireless device 410 may include input devices and circuits, output devices, and one or more synchronization units or circuits, whi ch may be part of the processing circuitry 520. Input devices include mechanisms for entry of data into wireless device 410. For example, input devices may include input mechanisms, such as a microphone, input elements, a display, etc. Output devices may include mechanisms for outputting data in audio, video, and/or hard copy format. For example, output devices may include a speaker, a display, etc.

FIGURE 7 is a block schematic of an exemplary network node 415, in accordance with certain embodiments. Network node 415 may be any type of radio network node or any network node that communicates with a UE and/or with another network node. Examples of network node 415 include an gNB, eNodeB, a node B, a base station, a wireless access point (e g., a Wi-Fi access point), a low power node, a base transceiver station (BTS), relay, donor node controlling relay, transmission points, transmission nodes, remote RF unit (RRU), remote radio head (RRH), multi -standard radio (MSR) radio node such as MSR BS, nodes in distributed antenna system (DAS), O&M, OSS, SON, positioning node (e.g., E-SMLC), MDT, or any other suitable network node. Network nodes 415 may be deployed throughout network 400 as a homogenous deployment, heterogeneous deployment, or mixed deployment. A homogeneous deployment may generally describe a deployment made up of the same (or similar) type of network nodes 415 and/or similar coverage and cell sizes and inter-site distances. A heterogeneous deployment may generally describe deployments using a variety of types of network nodes 415 having different cell sizes, transmit powers, capacities, and inter-site distances. For example, a heterogeneous deployment may include a plurality of low- power nodes placed throughout a macro-cell layout. Mixed deployments may include a mix of homogenous portions and heterogeneous portions.

Network node 415 may include one or more of transceiver 610, processing circuitry 620 (e.g., which may include one or more processors), memory 630, and network interface 640. In some embodiments, transceiver 610 facilitates transmitting wireless signals to and receiving wireless signals from wireless device 410 (e.g., via antenna 650), processing circuitry 620 executes instructions to provide some or all of the functionality described above as being provided by a network node 415, memory 630 stores the instructions executed by processing circuitry 620, and network interface 640 communicates signals to backend network components, such as a gateway, switch, router, Internet, Public Switched Telephone Network (PSTN), core network nodes or radio network controllers, etc.

Processing circuitry 620 may include any suitable combination of hardware and software implemented in one or more modules to execute instructions and manipulate data to perform some or all of the described functions of network node 415, such as those described in relation to any of sections 3, 4, or 6 herein. For example, in general, processing circuitry 620 may cause network node to send a paging message that includes a system information notification. In certain embodiments, the system information notification may be sent in response to detecting a change in the risk of an overload situation on access resources and may indicate that the wireless device 410 is to apply a previously stored version of system information. In some embodiments, processing circuitry 620 may include, for example, one or more computers, one or more central processing units (CPUs), one or more microprocessors, one or more applications, and/or other logic.

Memory 630 is generally operable to store instructions, such as a computer program, software, an application including one or more of logic, rules, algorithms, code, tables, etc. and/or other instructions capable of being executed by a processor. Examples of memory 630 include computer memory (for example, Random Access Memory (RAM) or Read Only Memory (ROM)), mass storage media (for example, a hard disk), removable storage media (for example, a Compact Disk (CD) or a Digital Video Disk (DVD)), and/or or any other volatile or non-volatile, non-transitory computer-readable and/or computer-executable memory devices that store information.

In some embodiments, network interface 640 is communicatively coupled to processing circuitry 620 and may refer to any suitable device operable to receive input for network node 415, send output from network node 415, perform suitable processing of the input or output or both, communicate to other devices, or any combination of the preceding. Network interface 640 may include appropriate hardware (e.g., port, modem, network interface card, etc.) and software, including protocol conversion and data processing capabilities, to communicate through a network.

Other embodiments of network node 415 may include additional components beyond those shown in FIGURE 7 that may be responsible for providing certain aspects of the radio network node's functionality, including any of the functionality described above and/or any additional functionality (including any functionality necessary to support the solutions described above). The various different types of network nodes may include components having the same physical hardware but configured (e.g., via programming) to support different radio access technologies, or may represent partly or entirely different physical components.

FIGURE 8 is a block schematic of an exemplary radio network controller or core network node 700, in accordance with certain embodiments. Examples of network nodes can include a mobile switching center (MSC), a serving GPRS support node (SGSN), a mobility management entity (MME), a radio network controller (RNC), a base station controller (BSC), and so on. The radio network controller or core network node includes processing circuitry 720 (e.g., which may include one or more processors), memory 730, and network interface 740. In some embodiments, processing circuitry 720 executes instructions to provide some or all of the functionality described above as being provided by the network node, memory 730 stores the instructions executed by processing circuitry 720, and network interface 740 communicates signals to any suitable node, such as a gateway, switch, router, Internet, Public Switched Telephone Network (PSTN), network nodes 415, radio network controllers or core network nodes, etc.

Processing circuitry 720 may include any suitable combination of hardware and software implemented in one or more modules to execute instructions and manipulate data to perform some or all of the described functions of the radio network controller or core network node. In some embodiments, processing circuitry 720 may include, for example, one or more computers, one or more central processing units (CPUs), one or more microprocessors, one or more applications, and/or other logic.

Memory 730 is generally operable to store instructions, such as a computer program, software, an application including one or more of logic, rules, algorithms, code, tables, etc. and/or other instructions capable of being executed by a processor. Examples of memory 930 include computer memory (for example, Random Access Memory (RAM) or Read Only Memory (ROM)), mass storage media (for example, a hard disk), removable storage media (for example, a Compact Disk (CD) or a Digital Video Disk (DVD)), and/or or any other volatile or non-volatile, non-transitory computer-readable and/or computer-executable memory devices that store information.

In some embodiments, network interface 740 is communicatively coupled to processing circuitry 720 and may refer to any suitable device operable to receive input for the network node, send output from the network node, perform suitable processing of the input or output or both, communicate to other devices, or any combination of the preceding. Network interface 740 may include appropriate hardware (e.g., port, modem, network interface card, etc.) and software, including protocol conversion and data processing capabilities, to communicate through a network.

Other embodiments of the network node may include additional components beyond those shown in FIGURE 8 that may be responsible for providing certain aspects of the network node's functionality, including any of the functionality described above and/or any additional functionality (including any functionality necessary to support the solution described above).

FIGURE 9 illustrates an example method 800 for improved BER performance in a transmitter, according to certain embodiments. In a particular embodiment, the transmitter may include a UE such as UE 410. In another particular embodiment, the transmitter may include a network node such as network node 415 or another network node.

At step 802, the transmitter transmits, in a first time slot, a first transmission according to a first mapping of bits to subcarrier indices.

At step 804, the transmitter obtains a second mapping of bits to subcarrier indices that is a re-arrangement of and varies from the first mapping of bits to subcarrier indices. In a particular embodiment, the second mapping of bits to subcarrier indices varies from the first mapping because the bits in the first transmission are transmitted using M-ary modulation and the bits in the second transmission are reassigned and transmitted using subcarrier indices. Alternatively, the bits in the first transmission are transmitted using subcarrier indices and the bits in the second transmission are reassigned and transmitted using M-ary modulation.

In another embodiment, the second mapping of bits to subcarrier indices may vary from the first mapping where a subblock size, n, of the second transmission is different from a subblock size, n, of the first transmission. Additionally, or alternatively, the second mapping of bits to subcarrier indices may vary from the first mapping where a number of subcarriers, k, of the second transmission are varied as compared to a number of subcarriers, k, of the first transmission. In either or both cases, a spectral efficiency, n/p (bit/sec/subcarrier) may be the same for the first and second transmissions.

In still another embodiment, obtaining the second mapping of bits to subcarrier indices may include generating the re-arrangement of the first mapping of bits to subcarrier indices. In a particular embodiment, for example, a lookup table may be generated that is the re- arrangement of the first mapping of bits to subcarrier indices. The lookup table may be transmitted to a receiver of the first and second transmissions. In another embodiment, the lookup table may be received from a network node.

At step 806, the transmitter transmits, in a second time slot, a second transmission according to the second mapping of bits to subcarrier indices. In a particular embodiment, the second time slot is the same size as the first time slot.

Certain embodiments may comprise more or fewer actions, and the actions may be performed in any suitable order.

In certain embodiments, the method for improved BER performance in a transmitter, as described above may be performed by a virtual computing device. FIGURE 10 illustrates an example virtual computing device 900 for improved BER performance in a transmitter, according to certain embodiments. In certain embodiments, virtual computing device 900 may include modules for performing steps similar to those described above with regard to the method illustrated and described in FIGURE 9. For example, virtual computing device 900 may include a first transmitting module 910, an obtaining module 920, a second transmitting module 930, and any other suitable modules for improved BER performance in a transmitter. In some embodiments, one or more of the modules may be implemented using processing circuitry 520 of FIGURE 6 or processing circuitry 620 of FIGURE 7. In certain embodiments, the functions of two or more of the various modules may be combined into a single module.

The first transmitting module 910 may perform certain of the transmitting functions of virtual computing device 900. For example, in a particular embodiment, first transmitting module 910 may transmit, in a first time slot, a first transmission according to a first mapping of bits to subcarrier indices.

The obtaining module 920 may perform certain of the obtaining functions of virtual computing device 900. For example, in a particular embodiment, obtaining module 920 may obtain a second mapping of bits to subcarrier indices that is a re-arrangement of and varies from the first mapping of bits to subcarrier indices.

The second transmitting module 930 may perform certain of the transmitting functions of virtual computing device 900. For example, in a particular embodiment, second transmitting module 930 may transmit, in a second time slot, a second transmission according to the second mapping of bits to subcarrier indices.

Other embodiments of virtual computing device 900 may include additional components beyond those shown in FIGURE 10 that may be responsible for providing certain aspects of the transmitter's functionality, including any of the functionality described above and/or any additional functionality (including any functionality necessary to support the solutions described above). The various different types of radio nodes which may comprise the transmitter may include components having the same physical hardware but configured (e.g., via programming) to support different radio access technologies, or may represent partly or entirely different physical components.

FIGURE 1 1 illustrates another example method 1000 in a transmitter, according to certain embodiments. In a particular embodiment, the transmitter may include a UE such as UE 410. In another particular embodiment, the transmitter may include a network node such as network node 415 or another network node.

At step 1002, the transmitter transmits, in a first time slot, a first transmission according to a first mapping of bits to indices. At step 1004, the transmitter transmits, in a second time slot, a second transmission according to a second mapping of bits to indices that is a re-arrangement of and varies from the first mapping of bits to indices. According to various particular embodiments, the indices may include antenna indices, subcarrier indices, or a combination thereof. According to a particular embodiment, the first time slot and the second time slot are the same size.

According to a particular embodiment, the indices include subcarrier indices and at least one of the following is true:

• a subblock size, n, of the second mapping of bits to indices is different from a subblock size, n, of the first mapping of bits of indices, and

• a number of activated subcarriers, k, of the second mapping of bits to indices is different from a number of activated subcarriers, k, of the first mapping of bits to indices.

According to a particular embodiment, the second mapping of bits to indices varies from the first mapping such that at least a portion of bits transmitted in the first transmission using M-ary modulation are transmitted in the second transmission using indices. According to another embodiment, the second mapping of bits to indices varies from the first mapping such that at least a portion of bits transmitted in the first transmission using indices are transmitted in the second transmission using M-ary modulation. The spectral efficiency, n/p (bit/sec/sub carrier) may be the same for the first and second transmissions, in a particular embodiment.

According to a particular embodiment, the method may further include generating the re-arrangement of the first mapping of bits to indices. For example, the transmitter may generate a lookup table associated with the second mapping of bits to indices that is the rearrangement of the first mapping of bits to indices. In a particular embodiment, the lookup table may be generated by performing a search for an optimal rearrangement of bits that offers a best bit error rate (BER) performance in the second time slot. Additionally, or alternatively, the lookup table may provide the second mapping to bits to indices for each sub-block in the second transmission.

According to a particular embodiment, after generating the lookup table, the transmitter may transmit the lookup table to a receiver of the first and second transmissions. In other embodiments, rather than generating the lookup table, the transmitter may receive the lookup table from a receiver of the first and second transmissions or from a network node.

In certain embodiments, the method in a transmitter, as described above may be performed by a virtual computing device. FIGURE 12 illustrates an example virtual computing device 1100, according to certain embodiments. In certain embodiments, virtual computing device 1100 may include modules for performing steps similar to those described above with regard to the method illustrated and described in FIGURE 10. For example, virtual computing device 1100 may include a first transmitting module 11 10, a second transmitting module 1 120, and any other suitable modules for improved BER performance in a transmitter. In some embodiments, one or more of the modules may be implemented using processing circuitry 520 of FIGURE 6 or processing circuitry 620 of FIGURE 7. In certain embodiments, the functions of two or more of the various modules may be combined into a single module.

The first transmitting module 11 10 may perform certain of the transmitting functions of virtual computing device 1 100. For example, in a particular embodiment, first transmitting module 1 1 10 may transmit, in a first time slot, a first transmission according to a first mapping of bits to indices.

The second transmitting module 1 120 may perform certain other of the transmitting functions of virtual computing device 1 100. For example, in a particular embodiment, second transmitting module 1 120 may transmit, in a second time slot, a second transmission according to the second mapping of bits to indices that is a re-arrangement of and varies from the first mapping of bits to indices.

Other embodiments of virtual computing device 1 100 may include additional components beyond those shown in FIGURE 12 that may be responsible for providing certain aspects of the transmitter's functionality, including any of the functionality described above and/or any additional functionality (including any functionality necessary to support the solutions described above). The various different types of radio nodes which may comprise the transmitter may include components having the same physical hardware but configured (e.g., via programming) to support different radio access technologies, or may represent partly or entirely different physical components.

FIGURE 13 illustrates an example method 1200 for improved BER performance in a receiver, according to certain embodiments. In a particular embodiment, the receiver may include a UE such as UE 410. In another particular embodiment, the receiver may include a network node such as network node 415 or another network node.

At step 1202, the receiver receives, in a first time slot, a first transmission according to a first mapping of bits to subcarrier indices.

At step 1204, the receiver obtains a second mapping of bits to subcarrier indices that is a rearrangement of and varies from the first mapping of bits to subcarrier indices. According to certain embodiments, the rearrangement of the first mapping of bits to subcarri er indices offers the best BER performance in the second time slot, where the second time slot and the first time slot are the same size.

In a particular embodiment, the second mapping of bits to subcarrier indices varies from the first mapping because the bits in the first transmission are transmitted using M-ary modulation and the bits in the second transmission are reassigned and transmitted using subcarrier indices. Alternatively, the bits in the first transmission are transmitted using subcarrier indices and the bits in the second transmission are reassigned and transmitted using M-ary modulation.

In a particular embodiment, obtaining the second mapping of bits to subcarrier indices may include receiving the second mapping of bits to subcarrier indices from a transmitter of the first and second transmissions. In another embodiment, obtaining the second mapping of bits to subcarrier indices comprises receiving a lookup table associated with the second mapping of bits to subcarrier indices from a network node. The lookup table provides the mapping to bits to subcarrier indices for each subblock in the second transmission.

At step 1206, the receiver receives, in a second time slot, a second transmission according to the second mapping of bits to subcarrier indices.

In certain embodiments, the method for improved BER performance in a receiver, as described above may be performed by a virtual computing device. FIGURE 14 illustrates an example virtual computing device 1300 for improved BER performance in a receiver, according to certain embodiments. In certain embodiments, virtual computing device 1300 may include modules for performing steps similar to those described above with regard to the method illustrated and described in FIGURE 13. For example, virtual computing device 1300 may include a first receiving module 1310, an obtaining module 1320, a second receiving module 1330, and any other suitable modules for improved BER performance in a receiver. In some embodiments, one or more of the modules may be implemented using processing circuitry 520 of FIGURE 6 or processing circuitry 620 of FIGURE 7. In certain embodiments, the functions of two or more of the various modules may be combined into a single module.

The first receiving module 1310 may perform certain of the receiving functions of virtual computing device 1300. For example, in a particular embodiment, first receiving module 1310 may receive, in a first time slot, a first transmission according to a first mapping of bits to subcarrier indices.

The obtaining module 1320 may perform certain of the obtaining functions of virtual computing device 1300. For example, in a particular embodiment, obtaining module 1320 may obtain a second mapping of bits to subcarrier indices that is a re -arrangement of and varies from the first mapping of bits to subcarrier indices.

The second receiving module 1330 may perform certain of the receiving functions of virtual computing device 1300. For example, in a particular embodiment, second transmitting module 1330 may transmit, in a second time slot, a second transmission according to the second mapping of bits to subcarrier indices.

Other embodiments of virtual computing device 1300 may include additional components beyond those shown in FIGURE 14 that may be responsible for providing certain aspects of the receiver's functionality, including any of the functionality described above and/or any additional functionality (including any functionality necessary to support the solutions described above). The various different types of radio nodes which may comprise the receiver may include components having the same physical hardware but configured (e.g., via programming) to support different radio access technologies, or may represent partly or entirely different physical components.

FIGURE 15 illustrates another example method 1400 in a receiver, according to certain embodiments. In a particular embodiment, the receiver may include a UE such as UE 410 or another wireless device. In another particular embodiment, the receiver may include a network node such as network node 415 or another network node.

At step 1402, the receiver receives, in a first time slot, a first transmission according to a first mapping of bits to indices. At step 1404, the receiver receives, in a second time slot, a second transmission according to a second mapping of bits to indices that is a rearrangement of and varies from the first mapping of bits to indices. According to various particular embodiment, the indices include antenna indices, subcarrier indices, or a combination thereof.

According to a particular embodiment, the second mapping of bits to indices varies from the first mapping such that at least a portion of bits transmitted in the first transmission using M-ary modulation are transmitted in the second transmission using indices.

According to a particular embodiment, the second mapping of bits to indices varies from the first mapping such that at least a portion of bits transmitted in the first transmission using indices are transmitted in the second transmission using M-ary modulation. The spectral efficiency, n/p (bit/sec/subcarrier) may be the same for the first and second transmissions, in a particular embodiment.

According to a particular embodiment, the method may further include generating the re-arrangement of the first mapping of bits to indices. For example, the receiver may generate a lookup table associated with the second mapping of bits to indices that is the re -arrangement of the first mapping of bits to indices. In a particular embodiment, the lookup table may be generated by performing a search for an optimal rearrangement of bits that offers a best bit error rate (BER) performance in the second time slot. Additionally, or alternatively, the lookup table may provide the second mapping to bits to indices for each sub-block in the second transmission.

According to a particular embodiment, after generating the lookup table, the receiver may transmit the lookup table to a transmitter of the first and second transmissions. In other embodiments, the lookup table may be received from a transmitter of the first and second transmissions or from a network node.

According to a particular embodiment, the first time slot and the second time slot are the same size.

According to a particular embodiment, the receiver may decode the first transmission based on the first mapping of bits to indices and decode the second transmission based on the second mapping of bits to indices.

In certain embodiments, the method in a receiver, as described above may be performed by a virtual computing device. FIGURE 16 illustrates an example virtual computing device 1500, according to certain embodiments. In certain embodiments, virtual computing device 1500 may include modules for performing steps similar to those described above with regard to the method illustrated and described in FIGURE 15. For example, virtual computing device 1500 may include a first receiving module 1510, a second receiving module 1520, and any other suitable modules for improved BER performance in a receiver. In some embodiments, one or more of the modules may be implemented using processing circuitry 520 of FIGURE 6 or processing circuitry 620 of FIGURE 7. In certain embodiments, the functions of two or more of the various modules may be combined into a single module.

The first receiving module 1510 may perform certain of the receiving functions of virtual computing device 1500. For example, in a particular embodiment, first receiving module 1510 may receive, in a first time slot, a first transmission according to a first mapping of bits to indices.

The second receiving module 1520 may perform certain other of the receiving functions of virtual computing device 1500. For example, in a particular embodiment, second receiving module 1520 may receive, in a second time slot, a second transmission according to the second mapping of bits to indices that is a re-arrangement of and varies from the first mapping of bits to indices.

Other embodiments of virtual computing device 1500 may include additional components beyond those shown in FIGURE 12 that may be responsible for providing certain aspects of the receiver's functionality, including any of the functionality described above and/or any additional functionality (including any functionality necessary to support the solutions described above). The various different types of radio nodes which may comprise the transmitter may include components having the same physical hardware but configured (e.g., via programming) to support different radio access technologi es, or may represent partly or entirely different physical components.

EXAMPLE EMBODIMENTS

According to certain example embodiments, a method for improved BER performance in a transmitter includes transmitting, in a first time slot, a first transmission according to a first mapping of bits to subcarrier indices. A second mapping of bits to subcarrier indices that is a re-arrangement of and varies from the first mapping of bits to subcarrier indices is obtained. A second transmission is transmitted in a second time slot according to the second mapping of bits to subcarrier indices.

Optionally, the second mapping of bits to subcarrier indices varies from the first mapping by the bits in the first transmission are transmitted using M-ary modulation and the bits in the second transmission are reassigned and transmitted using subcarrier indices.

Optionally, the second mapping of bits to subcarrier indices varies from the first mapping by the bits in the first transmission are transmitted using subcarrier indices and the bits in the second transmission are reassigned and transmitted using M-ary modulation.

Optionally, the second mapping of bits to subcarrier indices varies from the first mapping by a subblock size, n, of the second transmission is varied as compared to a subblock size, n, of the first transmission, and wherein a spectral efficiency, n/p (bit/sec/subcarrier) is the same for the first and second transmissions.

Optionally, the second mapping of bits to subcarrier indices varies from the first mapping by a number of subcarriers, k, of the second transmission is varied as compared to a number of subcarriers, k, of the first transmission, and wherein a spectral efficiency, n/p (bit/sec/subcarrier) is the same for the first and second transmissions.

Optionally, obtaining the second mapping of bits to subcarrier indices comprises generating the re-arrangement of the first mapping of bits to subcarrier indices.

Optionally, the method further comprises generating a lookup table associated with the second mapping of bits to subcarrier indices that is the re-arrangement of the first mapping of bits to subcarrier indices and transmitting, the lookup table associated with the second mapping of bits to subcarrier indices to a receiver of the first and second transmissions.

Optionally, generating the lookup table comprises performing a search for an optimal rearrangement of bits that offers the best BER performance in the second time slot.

Optionally, the method further comprises obtaining the second mapping of bits to subcarrier indices comprises receiving a lookup table associated with the second mapping from a network node.

Optionally, the lookup table provides the mapping to bits to subcarrier indices for each sub-block in the second transmission.

Optionally, the first time slot and the second time slot are the same size.

Optionally, the transmitter is a user equipment (UE).

Optionally, the transmitter is a network node.

According to certain embodiments, a transmitter to improve BER performance comprises a memory storing instructions and processing circuitry. The processing circuitry is operable to execute the instructions to cause the transmitter to transmit, in a first time slot, a first transmission according to a first mapping of bits to subcarrier indices, obtain a second mapping of bits to subcarrier indices that is a re -arrangement of and varies from the first mapping of bits to subcarrier indices, and transmit, in a second time slot, a second transmission according to the second mapping of bits to subcarrier indices.

Optionally, the second mapping of bits to subcarrier indices varies from the first mapping by a subblock size, n, of the second transmission is varied as compared to a subblock size, n, of the first transmission and wherein a spectral efficiency, n/p (bit/sec/subcarrier) is the same for the first and second transmissions.

Optionally, the second mapping of bits to subcarrier indices varies from the first mapping by a number of subcarriers, k, of the second transmission is varied as compared to a number of subcarriers, k, of the first transmission and wherein a spectral efficiency, n/p (bit/sec/subcarrier) is the same for the first and second transmissions.

Optionally, the processing circuitry is further operable to execute the instructions to cause the transmitter to generate a lookup table associated with the second mapping of bits to subcarrier indices that is the re-arrangement of the first mapping of bits to subcarrier indices and transmit the lookup table associated with the second mapping of bits to subcarrier indices to a receiver of the first and second transmissions.

Optionally, obtaining the second mapping of bits to subcarrier indices comprises receiving a lookup table associated with the second mapping from a network node.

Optionally, the lookup table provides the mapping to bits to subcarrier indices for each subblock in the second transmission.

Optionally, the first time slot and the second time slot are the same size.

Optionally, the transmitter is a user equipment (UE).

Optionally, the transmitter is a network node.

According to certain embodiments, a method to improve BER performance in a receiver comprises receiving, in a first time slot, a first transmission according to a first mapping of bits to subcarrier indices, obtaining a second mapping of bits to subcarrier indices that is a re-arrangement of and varies from the first mapping of bits to subcarrier indices, and receiving, in a second time slot, a second transmission according to the second mapping of bits to subcarrier indices.

Optionally, the second mapping of bits to subcarrier indices varies from the first mapping by a number of subcarriers, k, of the second transmission is varied as compared to a number of subcarriers, k, of the first transmission, and wherein a spectral efficiency, n/p (bit/sec/subcarrier) is the same for the first and second transmi ssions.

Optionally, obtaining the second mapping of bits to subcarrier indices comprises receiving the second mapping of bits to subcarrier indices from a transmitter of the first and second transmissions.

Optionally, obtaining second mapping of bits to subcarrier indices comprises receiving a lookup table associated with the second mapping of bits to subcarrier indices from a network node.

Optionally, the rearrangement of the first mapping of bits to subcarrier indices offers the best BER performance in the second time slot.

Optionally, the first time slot and the second time slot are the same size.

Optionally, the receiver is a user equipment (UE).

Optionally, the receiver is a network node.

According to certain embodiments, a receiver for improving BER performance comprises a memory storing instructions and processing circuitry. The processing circuitry is operable to execute the instructions to cause the receiver to receive, in a first time slot, a first transmission according to a first mapping of bits to subcarrier indices, obtain a second mapping of bits to subcarrier indices that is a re -arrangement of and varies from the first mapping of bits to subcarrier indices, and receive, in a second time slot, a second transmission according to the second mapping of bits to subcarrier indices.

Optionally, obtaining second mapping of bits to subcarrier indices comprises receiving a lookup table associated with the second mapping of bits to subcarrier indices from a transmitter of the first and second transmissions.

Optionally, obtaining the second mapping of bits to subcarrier indices comprises receiving a lookup table associated with the second mapping of bits to subcarrier indices from a network node.

Optionally, the first time slot and the second time slot are the same size.

Optionally, the receiver is a user equipment (UE).

Optionally, the receiver is a network node.

According to certain embodiments, a computer program product comprising a non- transitory computer readable medium storing computer readable program code, the computer readable program code comprises program code for performing any of the methods of example embodiments described above.

ABBREVIATIONS

Abbreviation Explanation

3 GPP 3^rd Generation Partnership Project

5G 5^th Generation

BER Bit Error Rate

C-MTC Critical MTC (Also referred to as Ultra Reliable and Low

Latency Communication (URLLC).)

CP Cyclic Prefix

DMRS Demodulation Reference Signal

eNB Evolved NodeB

gNB The term for a radio base station in NR (corresponding to eNB in LTE).

ID Identity/Identifier

IE Information Element IM Index Modulation

LTE Long Term Evolution

MIB Master Information Block

MFMO Multiple-Input Multiple-Output

ML Maximum Likelihood Detection

MSG Message

M-MTC Massive MTC

MTC Machine Type Communication

NGC Next Generation Core

NR New Radio (The term used for the 5G radio interface and radio access network in the technical reports and standard specifications 3GPP are working on.)

OFDM Orthogonal Frequency Division Multiple Access

PBCH Physical Broadcast Channel

PCI Physical Cell Identity

PDCCH Physical Downlink Control Channel

PDSCH Physical Downlink Shared Channel

PLMN Public Land Mobile Network

PRACH Physical Random Access Channel

PSS Primary Synchronization Signal

QAM Quadrature Amplitude Modulation

QCL Quasi-Co-Located

RA Random Access

RAN Random Access Network

RAR Random Access Response

RMSI Remaining Minimum System Information

RRC Radio Resource Control

SFN Single Frequency Network

SI System Information

SIB System Information Block

SM Spatial Modulation

SNR Signal to Noise Ratio

SS Synchronization Signal

SSS Secondary Synchronization Signal TRP Transmission/Reception Point

UE User Equipment

UL Uplink

Modifications, additions, or omissions may be made to the systems and apparatuses described herein without departing from the scope of the disclosure. The components of the systems and apparatuses may be integrated or separated. Moreover, the operations of the systems and apparatuses may be performed by more, fewer, or other components.

Additionally, operations of the systems and apparatuses may be performed using any suitable logic comprising software, hardware, and/or other logic. As used in this document, "each" refers to each member of a set or each member of a subset of a set.

Modifications, additions, or omissions may be made to the methods described herein without departing from the scope of the disclosure. The methods may include more, fewer, or other steps Additionally, steps may be performed in any suitable order.

Although this disclosure has been described in terms of certain embodiments, alterations and permutations of the embodiments will be apparent to those skilled in the art. Accordingly, the above description of the embodiments does not constrain this disclosure. Other changes, substitutions, and alterations are possible without departing from the spirit and scope of this disclosure.

Claims

1. A method in a transmitter comprising:

transmitting, in a first time slot, a first transmission according to a first mapping of bits to indices; and

transmitting, in a second time slot, a second transmission according to a second mapping of bits to indices that is a re-arrangement of and varies from the first mapping of bits to indices.

2. The method of Claim 1, wherein the indices comprise antenna indices.

3. The method of any one of Claims 1 to 2, wherein the indices comprise subcarrier indices.

4. The method of Claim 3, wherein at least one of:

a subblock size, n, of the second mapping of bits to indices is different from a subblock size, n, of the first mapping of bits of indices, and

a number of activated indices, k, of the second mapping of bits to indices is different from a number of activated indices, k, of the first mapping of bits to indices.

5. The method of any one of Claims 1 to 4, wherein the second mapping of bits to indices varies from the first mapping such that at least a portion of bits transmitted in the first transmission using M-ary modulation are transmitted in the second transmission using indices.

6. The method of any one of Claims 1 to 4, wherein the second mapping of bits to indices varies from the first mapping such that at least a portion of bits transmitted in the first transmission using indices are transmitted in the second transmission using M-ary modulation.

7. The method Claim 6, wherein a spectral efficiency, n/p (bit/sec/subcarrier) is the same for the first and second transmissions.

8. The method of any of Claims 1 to 7, further comprising generating the re-arrangement of the first mapping of bits to indices.

9. The method of any of Claims 1 to 8, further comprising:

generating a lookup table associated with the second mapping of bits to indices that is the re-arrangement of and varies from the first mapping of bits to indices; and

transmitting, the lookup table associated with the second mapping of bits to indices to a receiver of the first and second transmissions.

10. The method of Claim 9, wherein generating the lookup table comprises performing a search for an optimal second mapping that offers a better bit error rate (BER) performance in the second time slot.

1 1. The method of any one of Claims 1 to 8, further comprising receiving a lookup table associated with the second mapping from a network node.

12. The method of any one of Claims 1 to 8, further comprising receiving a lookup table associated with the second mapping from a receiver of the first and second transmissions.

13. The method of any one of Claims 9 to 12, wherein the lookup table provides the second mapping to bits to indices for each sub-block in the second transmission.

14. The method of any one of Claims 1 to 13, wherein the first time slot and the second time slot are the same size.

15. The method of any one of Claims 1 to 14, wherein the transmitter is a user equipment (UE).

16. The method of any one of Claims 1 to 14, wherein the transmitter is a network node.

17. A transmitter comprising:

a memory storing instructions; and

processing circuitry operable to execute the instructions to cause the transmitter to: transmit, in a first time slot, a first transmission according to a first mapping of bits to indices; and

transmit, in a second time slot, a second transmission according to a second mapping of bits to indices that is a re-arrangement of and varies from the first mapping of bits to indices.

18. The transmitter of Claim 17, wherein the indices comprise antenna indices.

19. The transmitter of any one of Claims 17 to 18, wherein the indices comprise subcarrier indices.

20. The transmitter of Claim 19, wherein at least one of:

a subblock size, n, of the second mapping of bits to indices is different from a subblock size, n, of the first mapping of bits to indices, and

21. The transmitter of any one of Claims 17 to 20, wherein the second mapping of bits to indices varies from the first mapping of bits to indices such that at least a portion of bits transmitted in the first transmission using M-ary modulation are transmitted in the second transmission using indices.

22. The transmitter of any one of Claims 17 to 20, wherein the second mapping of bits to indices varies from the first mapping of bits to indices such that at least a portion of bits transmitted in the first transmission using indices are transmitted in the second transmission using M-ary modulation.

23. The transmitter Claim 22, wherein a spectral efficiency, n/p (bit/sec/subcarrier) is the same for the first and second transmissions.

24. The transmitter of any of Claims 17 to 23, wherein the processing circuitry is further configured to execute the instructions to cause the transmitter to generate the re-arrangement of the first mapping of bits to indices.

25. The transmitter of any of Claims 17 to 24, wherein the processing circuitry is further configured to execute the instructions to cause the transmitter to:

generate a lookup table associated with the second mapping of bits to indices that is the re-arrangement of and varies from the first mapping of bits to indices; and

transmit the lookup table associated with the second mapping of bits to indices to a receiver of the first and second transmissions.

26. The transmitting of Claim 25, wherein generating the lookup table comprises performing a search for an optimal second mapping of bits that offers a better bit error rate (BER) performance in the second time slot.

27. The transmitter of any one of Claims 17 to 24, wherein the processing circuitry is further configured to execute the instructions to cause the transmitter to receive a lookup table associated with the second mapping of bits to indices from a network node.

28. The transmitter of any one of Claims 17 to 24, wherein the processing circuitry is further configured to execute the instructions to cause the transmitter to receive a lookup table associated with the second mapping of bits to indices from a receiver of the first and second transmissions.

29. The transmitter of any one of Claims 25 to 28, wherein the lookup table provides the second mapping to bits to indices for each sub-block in the second transmission.

30. The transmitter of any one of Claims 17 to 29, wherein the first time slot and the second time slot are the same size.

31. The transmitter of any one of Claims 17 to 30, wherein the transmitter is a user equipment (UE).

32. The transmitter of any one of Claims 17 to 30 wherein the transmitter is a network node.

33. A method in a receiver comprising:

receiving, in a first time slot, a first transmission according to a first mapping of bits to indices; and

receiving, in a second time slot, a second transmission according to a second mapping of bits to indices that is a re-arrangement of and varies from the first mapping of bits to indices.

34. The method of Claim 33, wherein the indices comprise antenna indices.

35. The method of any one of Claims 33 to 34, wherein the indices comprise subcarrier indices.

36. The method of Claim 35, wherein at least one of:

37. The method of any one of Claims 33 to 36, wherein the second mapping of bits to indices varies from the first mapping of bits to indices such that at least a portion of bits transmitted in the first transmission using M-ary modulation are transmitted in the second transmission using indices.

38. The method of any one of Claims 33 to 36, wherein the second mapping of bits to indices varies from the first mapping of bits to indices such that at least a portion of bits transmitted in the first transmission using indices are transmitted in the second transmission using M-ary modulation.

39. The method of Claim 38, wherein a spectral efficiency, n/p (bit/sec/subcarrier) is the same for the first and second transmissions.

40. The method of any of Claims 33 to 39, further comprising generating the rearrangement of the first mapping of bits to indices.

41. The method of any of Claims 33 to 40, further comprising:

generating a lookup table associated with the second mapping of bits to indices that is the re-arrangement of and varies from the first mapping of bits to indices.

42. The method of Claim 41, wherein generating the lookup table comprises performing a search for an optimal second mapping of bits that offers a better bit error rate (BER) performance in the second time slot.

43. The method of any of Claims 33 to 39, further comprising receiving a lookup table associated with the second mapping of bits to indices from a network node.

44. The method of any of Claims 33 to 39, further comprising receiving a lookup table associated with the second mapping of bits to indices from a transmitter of the first transmission and second transmission.

45. The method of any one of Claims 41 to 44, wherein the lookup table provides the mapping to bits to indices for each subblock in the second transmission.

46. The method of any one of Claims 33 to 45, wherein the first time slot and the second time slot are the same size.

47. The method of any one of Claims 33 to 46, further comprising:

using the first mapping of bits to indices when decoding the first transmission received in the first slot; and

using the second mapping of bits to indices when decoding the second transmission received in the second slot.

48. The method of any one of Claims 33 to 47, wherein the receiver is a user equipment (UE).

49. The method of any one of Claims 33 to 47, wherein the receiver is a network node.

50. A receiver comprising:

a memory storing instructions; and

processing circuitry operable to execute the instructions to cause the receiver to: receive, in a first time slot, a first transmission according to a first mapping of bits to indices; and

receive, in a second time slot, a second transmission according to a second mapping of bits to indices that is a re-arrangement of and varies from the first mapping of bits to indices.

51. The receiver of Claim 50, wherein the indices comprise antenna indices.

52. The receiver of any one of Claims 50 to 51 , wherein the indices comprise subcarrier indices.

53. The receiver of Claim 52, wherein at least one of:

54. The receiver of any one of Claims 50 to 53, wherein the second mapping of bits to indices varies from the first mapping of bits to indices such that at least a portion of bits transmitted in the first transmission using M-ary modulation are transmitted in the second transmission using indices.

55. The receiver of any one of Claims 50 to 53, wherein the second mapping of bits to indices varies from the first mapping of bits to indices such that at least a portion of bits transmitted in the first transmission using indices are transmitted in the second transmission using M-ary modulation.

56. The receiver of Claim 55, wherein a spectral efficiency, n/p (bit/sec/subcarrier) is the same for the first and second transmissions.

The receiver of any of Claims 50 to 56, wherein the processing circuitry is configured to execute the instmctions to cause the receiver to generate the re -arrangement of the first mapping of bits to indices.

58. The receiver of any of Claims 50 to 57, wherein the processing circuitry is configured to execute the instructions to cause the receiver to generate a lookup table associated with the second mapping of bits to indices that is the re -arrangement of and varies from the first mapping of bits to indices.

59. The receiver of Claim 58, wherein generating the lookup table comprises performing a search for an optimal second mapping of bits that offers a better bit error rate (BER) performance in the second time slot.

60. The receiver of any of Claims 50 to 57, wherein the processing circuitry is configured to execute the instructions to cause the receiver to receive a lookup table associated with the second mapping of bits to indices from a network node.

61. The receiver of any of Claims 50 to 57, wherein the processing circuitry is configured to execute the instructions to cause the receiver to receive a lookup table associated with the second mapping of bits to indices from a transmitter of the first transmission and second transmission.

62. The receiver of any one of Claims 58 to 61, wherein the lookup table provides the mapping to bits to indices for each subblock in the second transmission.

63. The receiver of any one of Claims 50 to 62, wherein the first time slot and the second time slot are the same size.

64. The receiver of any one of Claims 50 to 63, wherein the processing circuitry is configured to execute the instructions to cause the receiver to :

use the first mapping of bits to indices when decoding the first transmission received in the first slot; and

use the second mapping of bits to indices when decoding the second transmission received in the second slot.

65. The receiver of any one of Claims 50 to 64, wherein the receiver is a user equipment (UE).

66. The receiver of any one of Claims 50 to 64, wherein the receiver is a network node.

67. A computer program product comprising a non -transitory computer readable medium storing computer readable program code, the computer readable program code comprises program code for performing any of the methods of example Claims 1 to 16.

68. A computer program product comprising a non-transitory computer readable medium storing computer readable program code, the computer readable program code comprises program code for performing any of the methods of example Claims 33 to 49.