24 research outputs found
2-User Multiple Access Spatial Modulation
International audienceSpatial modulation (SM) is a recently proposed approach to multiple-input-multiple-output (MIMO) systems which entirely avoids inter-channel interference (ICI) and requires no synchronisation between the transmit antennas, while achieving a spatial multiplexing gain. SM allows the system designer to freely trade off the number of transmit antennas with the signal constellation. Additionally, the number of transmit antennas is independent from the number of receive antennas which is an advantage over other multiplexing MIMO schemes. Most contributions thus far, however, have only addressed SM aspects for a point-to-point communication systems, i.e. the single-user scenario. In this work we seek to characterise the behaviour of SM in the interference limited scenario. The proposed maximumlikelihood (ML) detector can successfully decode incoming data from multiple sources in an interference limited scenario and does not suffer from the near-far problem
Energy Efficient Transmission over Space Shift Keying Modulated MIMO Channels
Energy-efficient communication using a class of spatial modulation (SM) that
encodes the source information entirely in the antenna indices is considered in
this paper. The energy-efficient modulation design is formulated as a convex
optimization problem, where minimum achievable average symbol power consumption
is derived with rate, performance, and hardware constraints. The theoretical
result bounds any modulation scheme of this class, and encompasses the existing
space shift keying (SSK), generalized SSK (GSSK), and Hamming code-aided SSK
(HSSK) schemes as special cases. The theoretical optimum is achieved by the
proposed practical energy-efficient HSSK (EE-HSSK) scheme that incorporates a
novel use of the Hamming code and Huffman code techniques in the alphabet and
bit-mapping designs. Experimental studies demonstrate that EE-HSSK
significantly outperforms existing schemes in achieving near-optimal energy
efficiency. An analytical exposition of key properties of the existing GSSK
(including SSK) modulation that motivates a fundamental consideration for the
proposed energy-efficient modulation design is also provided
Spatial Modulation for Multiple-Antenna Wireless Systems : A Survey
International audienceMultiple-antenna techniques constitute a key technology for modern wireless communications, which trade-off superior error performance and higher data rates for increased system complexity and cost. Among the many transmission principles that exploit multiple-antenna at either the transmitter, the receiver, or both, Spatial Modulation (SM) is a novel and recently proposed multiple- uniqueness and randomness properties of the wireless channel for communication. This is achieved by adopting a simple but effective coding mechanism that establishes a one-to-one mapping between blocks of information bits to be transmitted and the spatial positions of the transmit-antenna in the antenna-array. In this article, we summarize the latest research achievements and outline some relevant open research issues of this recently proposed transmission technique
Performance analysis of non-linear generalised pre-coding aided spatial modulation
Developed from the recently emerged generalized pre-coding aided spatial modulation (GPSM) concept, a novel non-linear GPSM scheme based on the powerful vector perturbation philosophy is proposed, where a particular subset of receive antennas is activated and the specific activation pattern itself conveys useful implicit information in addition to the conventional modulated and perturbed symbols. Explicitly, both the infinite and finite alphabet capacities are derived for the proposed non-linear GPSM scheme. The associated complexity, energy efficiency, and error probability are also investigated. Our numerical results show that, as the only known non-linear realization within the spatial modulation family, the proposed scheme constitutes an attractive solution to the flexible design of green transceivers, since it is capable of striking a compelling compromise amongst the key performance indicators of throughput, energy consumption, complexity, and performance. In particular, in the challenging full-rank scenario, conveying information through receive antenna indices exhibits a lower complexity, a higher energy efficiency, and a better error resilience than that of the conventional arrangement
Extension and practical evaluation of the spatial modulation concept
The spatial modulation (SM) concept combines, in a novel fashion, digital modulation and
multiple antenna transmission for low complexity and spectrally efficient data transmission.
The idea considers the transmit antenna array as a spatial constellation diagram with the transmit
antennas as the constellation points. To this extent, SM maps a sequence of bits onto a
signal constellation point and onto a spatial constellation point. The information is conveyed
by detecting the transmitting antenna (the spatial constellation point) in addition to the signal
constellation point. In this manner, inter-channel interference is avoided entirely since transmission
is restricted to a single antenna at any transmission instance. However, encoding binary
information in the spatial domain means that the number of transmit antennas must be a power
of two. To address this constraint, fractional bit encoded spatial modulation (FBE—SM) is
proposed. FBE–SMuses the theory of modulus conversion to facilitate fractional bit rates over
time. In particular, it allows each transmitter to use an arbitrary number of transmit antennas.
Furthermore, the application of SM in a multi-user, interference limited scenario has never
been considered. To this extent, the average bit error rate (ABER) of SM is characterised in
the interference limited scenario. The ABER performance is first analysed for the interference-unaware detector. An interference-aware detector is then proposed and compared with the cost
and complexity equivalent detector for a single–input multiple–output (SIMO) system. The
application of SM with an interference-aware detector results in coding gains for the system.
Another area of interest involves using SM for relaying systems. The aptitude of SM to replace
or supplement traditional relaying networks is analysed and its performance is compared with
present solutions. The application of SM to a fixed relaying system, termed dual-hop spatial
modulation (Dh-SM), is shown to have an advantage in terms of the source to destination ABER
when compared to the classical decode and forward (DF) relaying scheme. In addition, the
application of SM to a relaying system employing distributed relaying nodes is considered and
its performance relative to Dh-SM is presented.
While significant theoretical work has been done in analysing the performance of SM, the implementation
of SM in a practical system has never been shown. In this thesis, the performance
evaluation of SM in a practical testbed scenario is presented for the first time. To this extent,
the empirical results validate the theoretical work presented in the literature
Index modulation for next generation radio communications.
Masters Degree. University of KwaZulu- Natal, Durban.Man’s insatiable desire for swift and more efficient internet service, a wide range of connectivity and increased data rate of transmission necessitated the need for further research to improve the efficiency of the existing systems. The development and evolution of the next-generation communication systems can be ascribed to the multiple-input multiple-output (MIMO) techniques implemented. The fundamental founding block of the MIMO systems is the spatial modulation (SM) which interestingly was able to attain high spectral efficiency as the receiver maintained significantly lower complexity. However, even with the feat achieved by the SM scheme, there was still a need improve on the performance of the SM scheme which meant an increase in the spectral efficiency was required, this prompted further research and a new scheme was introduced.
The quadrature SM (QSM) scheme was introduced to better the performance of the conventional SM. QSM retains all the good benefits the SM scheme offers, while still enhancing the spectral efficiency and improving overall throughput. However, the demand for increased reliability, i.e., improving the QSM scheme’s error performance led to a new scheme being introduced.
Space-time QSM (ST-QSM) improves the QSM scheme’s error performance by achieving second-order diversity gain for QSM. This scheme combines both the spatial dimension and diversity to the QSM scheme, bringing about a new and improved scheme.
In this dissertation, a scheme was introduced to fix the high computational complexity (CC) that affects MIMO systems transmitting at high data rates. Signal orthogonal projection (OP) was employed to decrease the CC of the space-time block coded spatial modulation (STBC-SM). The proposed scheme is called STBC-SM-OP and its results were investigated by comparing it with the STBC-SM with maximum likelihood detection (STBC-SM-ML). The proposed STBC-SM-OP scheme’s error performance matched that of STBC-SM-ML tightly down to low BER whilst maintaining a low CC
A universal space-time architecture for multiple-antenna aided systems
In this tutorial, we first review the family of conventional multiple-antenna techniques, and then we provide a general overview of the recent concept of the powerful Multiple-Input Multiple-Output (MIMO) family based on a universal Space-Time Shift Keying (STSK) philosophy. When appropriately configured, the proposed STSK scheme has the potential of outperforming conventional MIMO arrangements
Transmit antenna selection algorithms for quadrature spatial modulation.
Master of Science in Electronic Engineering. University of KwaZulu-Natal, Durban 2016.The use of multiple-input multiple-output (MIMO) systems has become increasingly popular due
to the demand for high data rate transmissions. One such attractive MIMO system is spatial
modulation (SM). SM is an ideal candidate for high data rate transmission as it is able to achieve
a high spectral efficiency, whilst maintaining a relatively low receiver complexity. SM completely
avoids inter-channel interference and the need for inter-antenna synchronisation. Furthermore,
SM requires the existence of only one radio frequency chain. However, the need to increase the
spectral efficiency achieved by SM is a topic which continues to garner interest.
Quadrature spatial modulation (QSM) was introduced as an innovative SM-based MIMO
system. QSM maintains the aforementioned advantages of SM, whilst further increasing the
spectral efficiency of SM. However, similar to SM, the need to improve the reliability (error
performance) of QSM still exists. One such strategy is the application of a closed-loop technique,
such as transmit antenna selection (TAS). In this dissertation, Euclidean distance-based antenna selection for QSM (EDAS-QSM) is
proposed. A substantial improvement in the average error performance is demonstrated. However,
this is at the expense of a relatively high computational complexity. To address this, we formulate
an algorithm in the form of reduced-complexity Euclidean distance-based antenna selection for
QSM (RCEDAS-QSM) that is used for the computation of EDAS-QSM. RCEDAS-QSM yields
a significant reduction in the computational complexity, whilst preserving the error performance.
To further address computational complexity, four sub-optimal, low-complexity, TAS
schemes for QSM are investigated, viz. capacity optimised antenna selection for QSM (COASQSM),
TAS for QSM based on amplitude and antenna correlation (TAS-A-C-QSM), lowcomplexity
TAS for QSM based on amplitude and antenna correlation using the splitting
technique (LCTAS-A-C-QSM) and TAS based on amplitude, antenna correlation and Euclidean
distance for QSM (A-C-ED-QSM).
Amongst the sub-optimal algorithms, A-C-ED-QSM provides superior error performance.
While the computational complexity of A-C-ED-QSM is higher than the other sub-optimal, lowcomplexity
schemes, there is a significant reduction in the computational complexity compared
to the optimal RCEDAS-QSM. However, this is at the expense of error performance. Hence,
clearly a trade-off exists between error performance and computational complexity, and is
investigated in detail in this dissertation