阅读说明：本技术 具有干扰抑制的多址接入方案 (Multiple access scheme with interference suppression ) 是由 严春林 袁志锋 于 2018-08-08 设计创作，主要内容包括：描述了一种用于具有干扰抑制的多址接入的方法、系统和设备。多址接入方案中的干扰抑制的示例性实施方式包括重排对应于输入比特流的第N部分的第N比特流,以生成K个重排比特流的第N重排比特流,对于N＝1、2、…、K,基于K个重排比特流生成分级QAM符号的调制符号流,其中来自第一重排比特流的比特对应于分级QAM符号的一个或多个最高有效比特,来自第K重排比特流的比特对应于分级QAM符号的一个或多个最低有效比特,并且来自第二到第(K-1)重排比特流的比特对应于分级QAM符号的一个或多个剩余比特,以及发送由调制符号流生成的信号。(A method, system, and device for multiple access with interference suppression are described. An exemplary embodiment of interference suppression in a multiple access scheme includes rearranging an nth bit stream corresponding to an nth portion of an input bit stream to generate an nth rearranged bit stream of K rearranged bit streams, generating a modulation symbol stream of hierarchical QAM symbols based on the K rearranged bit streams for N1, 2, …, K, wherein bits from the first rearranged bit stream correspond to one or more most significant bits of the hierarchical QAM symbols, bits from the kth rearranged bit stream correspond to one or more least significant bits of the hierarchical QAM symbols, and bits from the second through (K-1) th rearranged bit streams correspond to one or more remaining bits of the hierarchical QAM symbols, and transmitting a signal generated by the modulation symbol stream.)

1. A method for wireless communication, comprising:

(a) rearranging a first bitstream corresponding to a first portion of an input bitstream to generate a first rearranged bitstream, wherein the input bitstream comprises K portions, wherein K is an integer greater than 1, and wherein the first rearranged bitstream is a first element of a set of K rearranged bitstreams;

(b) rearranging an Nth bitstream corresponding to an Nth portion of the input bitstream to generate an Nth rearranged bitstream, the Nth rearranged bitstream being an Nth element of a set of K rearranged bitstreams, where N is an integer;

(c) for N-2, 3, …, K, performing step (b);

(d) generating a stream of modulation symbols of hierarchical QAM (Quadrature amplitude modulation) symbols based on a set of K rearranged bit streams, wherein bits from the first rearranged bit stream correspond to one or more most significant bits of the hierarchical QAM symbols, wherein bits from a Kth rearranged bit stream correspond to one or more least significant bits of the hierarchical QAM symbols, and wherein bits from second through (K-1) th rearranged bit streams correspond to one or more remaining bits of the hierarchical QAM symbols; and

(e) transmitting a signal generated from the modulation symbol stream.

2. The method of claim 1, wherein the reordering comprises interleaving, the interleaving being based on a set of K interleaving patterns.

3. The method of claim 2, wherein an mth interleaving pattern of the K interleaving patterns is defined as [1, 2, … B ]_M]In which B is_MIs the number of bits in the mth portion of the input bitstream, and wherein M is 1, 2, …, K;

4. the method of claim 2, wherein at least one of the set of K interleaving patterns is a User Equipment (UE) -specific interleaving pattern.

5. The method of claim 4, wherein the User Equipment (UE) -specific interleaving pattern is based on a UE Identification (ID).

6. The method of any of claims 1 to 5, wherein the reordering comprises scrambling, the scrambling being based on a set of K scrambling patterns.

7. The method of claim 6, wherein the scrambling is performed prior to the interleaving.

8. The method of claim 6, wherein the scrambling is performed after the interleaving.

9. The method of any of claims 6 to 8, wherein at least one scrambling pattern of the set of K scrambling patterns is a User Equipment (UE) -specific scrambling pattern.

10. The method of claim 9, wherein the User Equipment (UE) -specific scrambling pattern is based on a UE Identity (ID).

11. The method of claim 6, wherein at least one scrambling pattern of the set of K scrambling patterns is a cell-specific scrambling pattern.

12. The method of any one of claims 1-11, wherein the signal is generated by spreading the stream of modulation symbols, and wherein the spreading is based on a spreading factor and a spreading sequence.

13. The method of claim 12, wherein the spreading sequences have low cross-correlation.

14. The method according to claim 12 or 13, wherein the spreading factor is 2, where j²-1 and wherein said spreading sequence is defined as

15. The method according to claim 12 or 13, wherein the spreading factor is 4, where j²And wherein said spreading sequence is-1, andis defined as [0, 0,1, 1; 0,0,1, -1; 1,0, 1, 0; 1,0, -1, 0; 1,0, 0, 1; 1,0, 0, -1; 1, j, 0, 0; 1, -j, 0, 0; 0,1, 0, j; 0,1, 0, -j; 0,1, 1, 0; 0,1, -1,0]Or [1, 1,0, 0; 1, -1,0, 0; 1,0, j, 0; 1,0, -j, 0; 0,1, 0, 1; 0,1, 0, -1; 1,0, 0, j; 1,0, 0, -j; 0,1, j, 0; 0,1, -j, 0; 0,0,1, j; 0,0,1, -j]。

16. The method of claim 1, further comprising:

(f) encoding a qth portion of the input bitstream based on a channel code to generate a qth bitstream; and

(g) for Q ═ 1, 2, …, K, step (f) is performed.

17. The method of claim 16, further comprising:

repeating one or more bits of the qth bitstream a predetermined number of times.

18. The method of claim 16 or 17, further comprising:

bit flipping one or more bits of the Qth bitstream.

19. The method of claim 1, wherein the hierarchical QAM symbols are selected from a single QAM constellation.

20. The method of claim 1, wherein the hierarchical QAM symbol is selected from a superposition of a plurality of QAM constellations, and wherein each constellation of the plurality of QAM constellations comprises a different power ratio and a different rotation angle.

21. The method of claim 20, wherein the different power ratios and different rotation angles are selected over different time or frequency resources to balance minimizing an average block error rate (BLER) of the stream of modulation symbols and reducing a peak-to-average power ratio (PAPR) of the stream of modulation symbols.

22. The method of claim 20, wherein a power ratio of each of the plurality of QAM constellations is zero for at least one time or frequency resource.

23. The method of claim 20, wherein a power ratio of a number of QAM constellations of the plurality of QAM constellations is zero, and wherein the number is determined based on a minimum average block error rate.

24. The method of claim 20, wherein the integer K, the spreading factor, and the different power ratio are optimized upon determining that a number of information bits in the input bitstream have changed.

25. The method according to any of claims 20-24, wherein at least one of said plurality of QAM constellations is a QPSK (quadrature phase shift keying) constellation.

26. The method of claim 1, wherein the hierarchical QAM constellation is grayscale mapped.

27. A wireless communication apparatus comprising a processor and a memory, wherein the processor is configured to read code from the memory and implement the method of any of claims 1-26.

28. A computer program product comprising a computer readable program medium code stored thereon, which when executed by a processor causes the processor to implement the method of any of claims 1 to 26.

Technical Field

This document relates generally to wireless communications.

Background

Wireless communication technology is pushing the world to an increasingly interconnected and networked society. Rapid advances in wireless communications and advances in technology have resulted in greater demands for capacity and connectivity. Other aspects such as energy consumption, equipment cost, spectral efficiency and latency are important to meet the needs of various communication scenarios. Next generation systems and wireless communication technologies need to provide support for more users and devices than existing wireless networks, requiring robust interference suppression when using multiple access protocols.

Disclosure of Invention

This document relates to methods, systems, and devices for multiple access in the presence of interference. The disclosed technology describes methods that may be implemented on multiple mobile devices (or terminals, or user equipment) for ensuring that the multiple mobile devices are all able to access the network with minimal interference from each other.

In one exemplary aspect, a method of wireless communication is disclosed. The method includes (a) rearranging a first bit stream corresponding to a first portion of an input bit stream to generate a first rearranged bit stream, the input bit stream including K ≧ 2 portions, and wherein the first rearranged bit stream is a first element of a set of K rearranged bit streams, (b) rearranging an nth bit stream corresponding to an nth portion of the input bit stream to generate an nth rearranged bit stream, the nth rearranged bit stream being an nth element of a set of K rearranged bit streams, where N is an integer, (c) performing step (b) for N ═ 2, 3, …, K, (d) generating a modulated symbol stream of hierarchical QAM symbols based on the set of K rearranged bit streams, wherein bits from the first rearranged bit stream correspond to one or more most significant bits of the hierarchical QAM symbols, bits from the kth rearranged bit stream correspond to one or more least significant bits of the hierarchical QAM symbols, and bits from the second through (K-1) th rearranged bit streams correspond to one or more remaining bits of the hierarchical QAM symbol, and (e) transmitting a signal generated by modulating the symbol stream.

In yet another exemplary aspect, the above-described method is embodied in the form of processor executable code and stored in a computer readable program medium.

In yet another exemplary embodiment, an apparatus configured or operable to perform the above method is disclosed.

The above and other aspects and embodiments thereof are described in more detail in the accompanying drawings, the description and the claims.

Drawings

Fig. 1 illustrates an example of a Base Station (BS) and a User Equipment (UE) in wireless communications, in accordance with some embodiments of the disclosed technology.

Fig. 2A and 2B show examples of bit-to-symbol mapping for 16-QAM (quadrature amplitude modulation) and 64-QAM constellations, respectively.

Fig. 3 shows an example of transmitter processing for multiple access.

Fig. 4 shows another example of transmitter processing for multiple access.

Fig. 5A and 5B show a first example of transmitter processing for multiple access supporting interference suppression.

Fig. 6A and 6B illustrate a second example of transmitter processing for multiple access supporting interference suppression.

Fig. 7A and 7B illustrate examples of different 16-QAM constellations that may be used on different subcarriers in an OFDM system.

Fig. 8 shows an example of a wireless communication method that may be implemented on a wireless communication device (or user equipment).

Fig. 9 illustrates an example of another wireless communication method that may be implemented on a wireless communication device (or user equipment).

Fig. 10 is a block diagram representation of a portion of an apparatus in accordance with some embodiments of the disclosed technology.

Detailed Description

In recent years, non-orthogonal multiple access (NOMA) schemes have gained widespread attention in fifth generation (5G) cellular networks. One of the reasons for implementing NOMA 5G is that NOMA is able to serve multiple users using the same time, frequency and space resources. Some examples of NOMA techniques are based on power domain multiple access, code domain multiple access, pattern division multiple access (pattern division multiple access), multi-user shared multiple access, and resource extension multiple access, e.g., power domain NOMA implements multiplexing in the power domain and code domain NOMA implements multiplexing in the code domain.

In one prior embodiment, linear spreading may be applied in combination with different spreading codes as multiple access signatures. By carefully designing the spreading codes, multi-user interference can be effectively suppressed. To obtain high spectral efficiency, higher order modulation may be used, although the bit reliability of each bit in the higher order modulation is different. In other words, some bits have high reliability, and some bits have low reliability. In case the same channel coding is applied to all bits, bits with low reliability typically degrade the overall system performance.

Fig. 1 shows an example of a wireless communication system (e.g., a 5G or NR cellular network) including a Base Station (BS)120 and one or more User Equipments (UEs) 111, 112 and 113. In some embodiments, the UE accesses the BS (e.g., network) using an implementation of the disclosed techniques (131, 132, 133), which then enables subsequent communication (141, 142, 143) from the BS to the UE. The UE may be, for example, a smartphone, a tablet, a mobile computer, a machine-to-machine (M2M) device, an internet of things (IoT) device, and so on.

Fig. 2A shows an example of a bit-to-symbol mapping for a 16-QAM constellation, where each QAM symbol is represented using 4 bits. As shown in fig. 2A, for the exemplary symbol "1011", the two most significant bits ("10") are high reliability bits, and the two least significant bits ("11") are low reliability bits. This is due to all four symbols (e.g., "1011", "1001", "1010" and "1000") in the upper left quadrant of the 16-QAM constellation having the same two most significant bits ("10"). Similarly, all four symbols in each quadrant have the same two most significant bits. This enables the QAM symbols to be transmitted and received as hierarchical QAM symbols, as will be described.

Fig. 2B shows an example of bit-to-symbol mapping for a 64-QAM constellation, where each QAM symbol is represented using 6 bits. As shown in fig. 2B, for the exemplary symbol "101111", the two most significant bits ("10") are high reliability bits, while the two middle significant bits ("11") are medium reliability bits, and the two least significant bits ("11") are low reliability bits. Similarly, all sixteen symbols in each quadrant have the same two most significant bits, and four symbols in each quadrant have the same two most significant bits. This enables the QAM symbols to be transmitted and received as hierarchical QAM symbols, as will be described.

In some prior embodiments, multi-stream transmission is implemented, where multiple data streams with QPSK modulation are used. In addition, orthogonal spreading codes may be applied to suppress multi-stream interference. For example, when there are 6 users, each user has two data streams with a spreading length of 2, which requires 12 orthogonal spreading codes. However, it is theoretically impossible to design 12 orthogonal spreading codes with a spreading length of 2.

Fig. 3 shows an example of a prior art implementation for multiple access. As shown therein, the two streams are separately encoded and jointly modulated.

Fig. 4 shows another example of a prior art implementation for multiple access. As shown therein, the two streams are encoded, interleaved, and modulated separately, and the power ratio of each modulation symbol stream can be adjusted independently for each data stream. However, the prior embodiments as shown in fig. 3 and 4 typically do not employ bit-to-symbol grayscale mapping, which can degrade (minimum mean square error) performance of MMSE-SIC (successive interference cancellation) receivers. Furthermore, they are not used and constellation rotation can be used to reduce peak-to-average power ratio (PAPR).

Embodiments of the disclosed technology overcome these disadvantages and may implement one or more of constellation rotation, grayscale mapping, power ratio, and rotation angle optimization to improve system performance when using MMSE-SIC or iterative receivers.

Fig. 5A and 5B show examples of a first type of transmitter processing for multiple access supporting interference suppression with two data streams. As shown in fig. 5A, after channel coding, a different interleaver may be applied to each of the two data streams (e.g., with a different interleaving pattern), after which it is scrambled (e.g., each of the two data streams with a different scrambling pattern). In fig. 5B, a scrambling operation may be performed before an interleaving operation. The different interleaving patterns advantageously randomize the multi-user interference, thereby improving system performance when using an iterative detector. In some embodiments, implementation complexity may be reduced by having different interleavers use a common cyclic shift of the interleaving pattern (e.g., the cyclic shift value of each interleaver is different). For example, different users and different data streams may have different cyclic shifts. In some embodiments, irregular constellations may be used during the modulation phase to advantageously reduce PAPR and improve system performance.

Fig. 6A and 6B illustrate examples of a second type of transmitter processing for multiple access supporting interference suppression. This example includes some features and/or components similar to those shown in fig. 5 and described above. At least some of these features and/or components are not separately described in this section.

As shown in fig. 6A and 6B, the transmitter processing may include spreading, thereby embodying the advantages of both the interleaver-based NOMA scheme and the spread spectrum-based NOMA scheme. In some embodiments, transmitter processing as shown in fig. 6A and 6B may be used in conjunction with a receiver implementing MMSE-SIC or an iterative detector such as ESE (basic signal estimator) or EPA (desired propagation algorithm).

In some embodiments, the criteria for designing the spreading codes are different for the MMSE-SIC detector and the iterative detector. When applying an MMSE-SIC detector, the spreading codes should generally have low cross-correlation to reduce multi-user interference. On the other hand, for iterative detectors, short periods should be avoided in the graph representation of the decoding algorithm. For example, short periods can be significantly reduced by adding zeros in the spreading code. Thus, in some embodiments, zeros may be included in the spreading code design.

For example, for a spreading length of 2, the spreading codes shown in table 1 may be used.

Table 1: example spreading code with spreading length of 2

For example, for a spreading length of 3, the spreading codes shown in table 2 may be used.

Table 2: exemplary spreading code with spreading length of 3

For example, for a spreading length of 4, the spreading code shown in table 3 may be used.

Table 3: exemplary spreading code with spreading length of 4

0	[1,1,0,0]	8	[1,0,0,1]	16	[0,1,0,1]
						1	[1,-1,0,0]	9	[1,0,0,-1]	17	[0,1,0,-1]
2	[1,j,0,0]	10	[1,0,0,j]	18	[0,1,0,j]
						3	[1,-j,0,0]	11	[1,0,0,-j]	19	[0,1,0,-j]
4	[1,0,1,0]	12	[0,1,1,0]	20	[0,0,1,1]
						5	[1,0,-1,0]	13	[0,1,-1,0]	21	[0,0,1,-1]
6	[1,0,j,0]	14	[0,1,j,0]	22	[0,0,1,j]
						7	[1,0,-j,0]	15	[0,1,-j,0]	23	[0,0,1,-j]

The ideal sequences selected are those with low correlation that will achieve the best block error rate performance. For example, if there are 12 users, the sequence may be [0, 0,1, 1; 0,0,1, -1; 1,0, 1, 0; 1,0, -1, 0; 1,0, 0, 1; 1,0, 0, -1; 1, j, 0, 0; 1, -j, 0, 0; 0,1, 0, j; 0,1, 0, -j; 0,1, 1, 0; 0,1, -1,0]. Since 24 sequences are shown in table 3, other 12 sequences can be selected. In the sequences described, [0, 0,1, 1; 0,0,1, -1] can be replaced with [0, 0,1, j; 0,0,1, -j, [0, 0,1, j; 0,0,1, -j ] can be replaced with [0, 0,1, 1; 0,0,1, -1], and so on.

As shown in fig. 6, the two data streams are superimposed, thereby avoiding the need to suppress interference from the two data streams mapped on the same symbol. In some embodiments, a joint MMSE operation may be performed on two data streams mapped on the same symbol. After demodulation, the first two bits of soft information are input to a channel decoder, and the last two bits of soft information are processed by an interleaver and input to another channel decoder. When the data stream mapped on the high reliability bits is successfully decoded, the data stream can be removed from the received signal by using soft information output from the decoder. Such an embodiment may facilitate detection and decoding of data streams mapped on low reliability bits.

In some embodiments, bit repetition is included in the channel coding. For example, if the bit repetition number is 2, the code rate of 2/3 is used, and an equivalent code rate of 1/3 is obtained. Bit repetition generally improves block error rate performance when the number of users is large. As an example after channel coding, if the output bit sequence is "[ 0,1, 0,0,1, 1 ]", the result of the bit repetition being 2 yields "[ 0,0,1, 1,0, 0,0, 0,1, 1, 1, 1 ]".

In some embodiments, bit flipping may be applied with bit repetition to further randomize the input bits. In bit flipping, a "0" bit becomes a "1" bit, and vice versa. As shown in the above example, the channel coded output bit sequence is "[ 0,1, 0,0,1, 1 ]", the bit repetition is 2 and the result of the bit flipping is "[ 0,1, 1,0, 0,1, 0,1, 1,0, 1,0 ]", where the second bit of the bit repetition has been flipped.

In some embodiments, the constellation of the joint bit-to-symbol mapping may be represented as follows:

here, p₁And p₂Power, θ, allocated to streams 1 and 2, respectively₁And theta₂Phase rotation for streams 1 and 2, respectively, and s₁And s₂May be points from the QPSK constellation. More generally, the constellation points may be represented as:

here, p_iAnd theta_iIs the power allocated to and phase rotation for stream i, and s_iMay be points from the QPSK constellation. Power allocation and phase allocation may be used to improve block error rate performance or reduce peak-to-average power ratio (PAPR). For different users, the method can be used for adjusting the information length, the block length, the spreading factor and the dataThe number of streams, the power ratio and the rotation angle to achieve the best block error rate performance and PAPR performance.

Regarding the PAPR, a single carrier frequency division multiple access (SC-FDMA) scheme has a lower PAPR than an OFDM system having frequency domain spreading. The latter approach may be used to implement embodiments of the disclosed technology, which may be improved by using different constellations on different subcarriers when spreading is employed. In other words, when spread spectrum is used (as shown in fig. 6), the constellation of each OFDM subcarrier can be changed by adjusting the respective power ratio and phase rotation angle in order to reduce PAPR.

Fig. 7A and 7B show examples of 16-point constellations with different power ratios and phase rotation angles. In some embodiments, spreading may be achieved by multiplying the symbols by a spreading sequence (e.g., from the set [0, 1, -1, j, -j ]) after repetition. This advantageously results in reduced PAPR.

In some embodiments, higher order modulation may be employed, in which case the input bit stream may be divided into multiple component streams (e.g., K), each of which is encoded separately. The coded bits may be randomized using a different interleaving pattern for each stream. In one example, after that, stream 1 is mapped to the highest priority bits (also referred to as the most significant bits or the most reliable bits), stream 2 is mapped to the bits with the next highest priority, and so on, stream K is mapped to the lowest priority bits.

In some embodiments, the shape of the final constellation is based on power allocation and phase rotation between the K different streams.

In some embodiments, the power ratio of all K different streams is zero for the partial signal. The transmitted information can be recovered from the residual signal, which has K different streams with a power ratio greater than zero. By setting the power ratio of the K different streams to zero for the partial signal, interference between signals from different users can be reduced, which facilitates recovery of transmitted information. The amount of signal with a power ratio of zero is determined by achieving minimum block error rate performance.

In some embodiments, a gray-scale bit-to-symbol mapping may be employed, where only one bit changes between adjacent symbols. When MMSE-SIC is used in these embodiments, the grayscale mapping advantageously improves the system block error rate performance.

As described above, embodiments of the disclosed technology enable multiple access while supporting interference suppression by adapting and adapting transmitter processing at each terminal (or mobile device or UE). In some embodiments, techniques that may be used alone or in any combination include:

(1) the input data stream is divided into K streams with separate channel coding and different interleaving patterns, randomizing the coded bits. All K streams may be jointly modulated onto a constellation with grey-coded bit-to-symbol mapping, such that stream 1 is mapped to the highest priority bit of the constellation symbol, stream 2 is mapped to the second highest priority bit, and so on, stream K is mapped to the lowest priority bit.

(2) Due to the power allocation and phase rotation, the constellation is interpreted (at the iterative or MMSE-SIC receiver) as a superposition of two smaller size constellations. For example, in the example shown in fig. 7A and 7B, each point of the "parent" QPSK constellation may be the center of the "child" QPSK constellation.

(3) The power ratio and the rotation angle may be different on different subcarriers.

Fig. 8 illustrates an example of a wireless communication method 800 for multiple access supporting interference mitigation. At step 810, method 800 includes dividing the information data into K independent data streams.

At step 820, method 800 includes performing channel coding on each data stream. In some embodiments, the same channel code is applied to each data stream.

At step 830, method 800 includes performing bit changes on the channel coded bits for each data stream. In some embodiments, the bit change comprises a bit repetition, a bit flip, or a bit flip after a bit repetition. In other embodiments, the bit alteration may include an interleaving operation and a scrambling operation, which may be performed in any order.

At step 840, method 800 includes mapping bits of stream 1 to constellation positions having the highest reliability, mapping bits of stream 2 to constellation positions having the second highest reliability … …, mapping bits of stream K to constellation positions having the lowest reliability, and finally applying a grayscale bit to symbol mapping.

At step 850, the method 800 includes that the shape of the constellation can be viewed as K QPSK signal stacks with different power ratios and phase rotations, which can vary over different time, frequency and spatial resources.

Fig. 9 illustrates another example of a wireless communication method 900 for multiple access supporting interference mitigation. At step 910, the method 900 includes rearranging a first bit stream (including K ≧ 2 portions) corresponding to a first portion of the input bit stream to generate a first rearranged bit stream.

At step 920, the method 900 includes rearranging an nth bit stream corresponding to an nth portion of the input bit stream to generate an nth rearranged bit stream, which is an nth element of a set of K rearranged bit streams. In some embodiments, the reordering comprises interleaving in the set based on K interleaving patterns. For example, the definition of [1, 2, … B ] can be used_M]Skipping the interleaving step in the mth interleaving mode of (1), wherein B_MIs the number of bits in the mth part of the input bitstream, and where M is 1, 2, …, K. In one example, the interleaving pattern may be a User Equipment (UE) -specific interleaving pattern. In another example, the UE-specific interleaving pattern may be based on UE identity.

In some embodiments, the reordering comprises scrambling based on a set of K scrambling patterns. In one example, scrambling is performed before interleaving, and in another example, scrambling is performed after interleaving. In yet another example, the scrambling pattern is a User Equipment (UE) -specific scrambling pattern, which may be based on a UE identity, or it may be a cell-specific scrambling pattern.

At step 930, method 900 includes performing step 920 for N — 2, 3, …, K.

At step 940, method 900 includes generating a stream of modulation symbols of hierarchical QAM symbols based on a set of K rearranged bit streams, wherein bits from a first rearranged bit stream correspond to one or more most significant bits of the hierarchical QAM symbols, bits from a kth rearranged bit stream correspond to one or more least significant bits of the hierarchical QAM symbols, and bits from a second through (K-1) th rearranged bit streams correspond to one or more remaining bits of the hierarchical QAM symbols.

In some embodiments, the hierarchical QAM symbols are selected from a single QAM constellation. In other embodiments, the hierarchical QAM symbol is selected from a superposition of a plurality of QAM constellations, wherein each of the plurality of QAM constellations comprises a different power ratio and a different rotation angle. In one example, different power ratios and rotation angles are selected over different time or frequency resources to balance minimizing the average block error rate (BLER) and reducing the peak-to-average power ratio (PAPR) of the modulation symbol stream.

In some embodiments, the signal is generated by spreading a stream of modulation symbols, and wherein the spreading is based on a spreading factor and a spreading sequence. In one example, the spreading sequences have low cross-correlation.

At step 950, method 900 includes transmitting a signal generated from a stream of modulation symbols.

Fig. 9 is a block diagram representation of a portion of an apparatus in accordance with some embodiments of the disclosed technology. An apparatus 905, such as a base station or wireless device (or UE), may include processor electronics 910, such as a microprocessor, that implements one or more of the techniques presented in this document. The apparatus 905 may include transceiver electronics 915 to transmit and/or receive wireless signals through one or more communication interfaces 920 (such as an antenna). The apparatus 905 may include other communication interfaces for sending and receiving data. The apparatus 905 may include one or more memories (not explicitly shown) configured to store information, such as data and/or instructions. In some implementations, the processor electronics 910 can include at least a portion of the transceiver electronics 915. In some embodiments, at least some of the disclosed techniques, modules, or functions are implemented using an apparatus 905.

This description, together with the drawings, is to be considered exemplary, in that the illustrations are meant to be exemplary, and not meant to imply ideal or preferred embodiments unless otherwise indicated. As used herein, the use of "or" is intended to include "and/or" unless the context clearly indicates otherwise.

Some embodiments described herein are described in the general context of methods or processes, which may be implemented in one embodiment by a computer program product, embodied in a computer-readable medium, including computer-executable instructions, such as program code, executed by computers in networked environments. Computer-readable media may include removable and non-removable storage devices, including but not limited to Read Only Memory (ROM), Random Access Memory (RAM), Compact Disks (CDs), Digital Versatile Disks (DVDs), and the like. Thus, a computer-readable medium may include a non-transitory storage medium. Generally, program modules may include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types. Computer-or processor-executable instructions, associated data structures, and program modules represent examples of program code for executing steps of the methods disclosed herein. The particular sequence of such executable instructions or associated data structures represents examples of corresponding acts for implementing the functions described in such steps or processes.

Some embodiments disclosed may be implemented as a device or module using hardware circuitry, software, or a combination thereof. For example, a hardware circuit implementation may include, for example, discrete analog and/or digital components integrated as part of a printed circuit board. Alternatively or additionally, the disclosed components or modules may be implemented as Application Specific Integrated Circuits (ASICs) and/or Field Programmable Gate Array (FPGA) devices. Some implementations may additionally or alternatively include a Digital Signal Processor (DSP), which is a special-purpose microprocessor having an architecture optimized for the operational requirements of digital signal processing related to the functions disclosed herein. Similarly, the various components or sub-components within each module may be implemented in software, hardware, or firmware. Connections between modules and/or connections between components within a module may be provided using any of the connection methods and media known in the art, including but not limited to communications over the internet, wired, or wireless networks using an appropriate protocol.

Although this document contains many specifics, these should not be construed as limitations on the scope of the claimed invention or of what may be claimed, but rather as descriptions of features specific to particular embodiments. Certain features that are described herein in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable subcombination. Moreover, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a subcombination or variation of a subcombination. Similarly, while operations are depicted in the drawings in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results.

Only some embodiments and examples are described herein, and other embodiments, enhancements and variations can be obtained based on what is described and illustrated in this disclosure.