Exploiting Indices of Silent Antennas to Increase the Spectral Efficiency of SSK

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Exploiting Indices of Silent Antennas to Increase the Spectral Efficiency of SSK

Exploiting Indices of Silent Antennas to Increase the Spectral Efficiency of SSK

By Nafel N. Alotaibi & Khairi A. Hamdi

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Introduction

• Space shift keying (SSK) modulation exploits the multipath phenomena to identify which of the transmitting antennas was used, based on the fact that the path of every antenna signal is unique and no other signal can pass through this way except from the same antenna.

• In SSK and generalized SSK, the symbols are transmitted only by the active antennas’ indices, while the inactive antennas remain unexploited; this limits the spectral efficiency.

• To combat this limitation, we propose a direct-code for space shift Keying (DC-SSK) modulation technique.

EXPLOITING INDICES OF SILENT ANTENNAS TO INCREASE THE SPECTRAL EFFICIENCY OF SSK

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The Contribution

• We propose a Direct-Code Space Shift Keying (DC-SSK) as a new physical layer coding scheme, to improve the spectral efficiency by exploiting the indices of both the silent and active antennas, to convey the information.

• In DC-SSK, the transmitter is allowed to use 0, 1, ..., N antennas for each symbol, and groups of N bits are used to derive the transmitting antennas directly according to the bit value, active for ’1’ and inactive for ’0’.

• We analysed the performance of DC-SSK and validate the results by simulation, and the results show that DC-SSK is a promising solution to respond to the massive demand on the data rates since it increases the data rate linearly with N.


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SM


DATA

Select the antenna

ConventionalModulation

0

1

Ex:Data=01Modulation= BPSK

01

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From SM to SSK


DATA

Select the antenna

ConventionalModulation

0

1

01

6EXPLOITING INDICES OF SILENT ANTENNAS TO INCREASE THE SPECTRAL EFFICIENCY OF SSK

DC-SSK Principle

…0111010000110100tN …0 1 0 0 0 1 0 0

…1 1 1 0 0 1 1 0Grouping

Time slots


DC-SSK Example

…0111010000110100tN …0 1 0 0 0 1 0 0

…1 1 1 0 0 1 1 0Grouping

Time slots


DC-SSK Nyquest Capacity

For a noiseless channel, Nyquest Capacity formula C = 2B log2 (M) relates the capacity with the number of signal levels (constellation size)

𝐶𝑆𝑆𝐾=2 log2 (𝑁𝑡 )

=


Performance Analysis

The final form of probability of error


The Bit-rate


Upper Bounds of DC-SSK and SSK BER


BER vs SNR

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Conclusion

• DC-SSK is a new physical layer coding scheme to improve the spectral efficiency of SSK modulation.

• DC-SSK increases the data rate linearly with the number of transmitting antennas.

• The results show that DC-SSK is a promising solution to respond to the massive demand on the data rates.



Engineering

Exploiting Indices of Silent Antennas to Increase the Spectral Efficiency of SSK