Date post: | 15-Apr-2017 |
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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.
EXPLOITING INDICES OF SILENT ANTENNAS TO INCREASE THE SPECTRAL EFFICIENCY OF SSK
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SM
EXPLOITING INDICES OF SILENT ANTENNAS TO INCREASE THE SPECTRAL EFFICIENCY OF SSK
DATA
Select the antenna
ConventionalModulation
0
1
Ex:Data=01Modulation= BPSK
01
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From SM to SSK
EXPLOITING INDICES OF SILENT ANTENNAS TO INCREASE THE SPECTRAL EFFICIENCY OF 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
7EXPLOITING INDICES OF SILENT ANTENNAS TO INCREASE THE SPECTRAL EFFICIENCY OF SSK
DC-SSK Example
…0111010000110100tN …0 1 0 0 0 1 0 0
…1 1 1 0 0 1 1 0Grouping
Time slots
8EXPLOITING INDICES OF SILENT ANTENNAS TO INCREASE THE SPECTRAL EFFICIENCY OF SSK
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 )
=
9EXPLOITING INDICES OF SILENT ANTENNAS TO INCREASE THE SPECTRAL EFFICIENCY OF SSK
Performance Analysis
The final form of probability of error
10EXPLOITING INDICES OF SILENT ANTENNAS TO INCREASE THE SPECTRAL EFFICIENCY OF SSK
The Bit-rate
11EXPLOITING INDICES OF SILENT ANTENNAS TO INCREASE THE SPECTRAL EFFICIENCY OF SSK
Upper Bounds of DC-SSK and SSK BER
12EXPLOITING INDICES OF SILENT ANTENNAS TO INCREASE THE SPECTRAL EFFICIENCY OF SSK
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.
EXPLOITING INDICES OF SILENT ANTENNAS TO INCREASE THE SPECTRAL EFFICIENCY OF SSK
14EXPLOITING INDICES OF SILENT ANTENNAS TO INCREASE THE SPECTRAL EFFICIENCY OF SSK