Performance of an OFDM-CDMA HF modem

Raos, I.; Cacho, A. Del; Álvarez, Irina Argüelles; Zazo, Santiago; Mendieta-Otero, E.; Santana-Sosa, H.; Pàez-Borrallo, J.M.

doi:10.1049/cp:20030425

Cited by 6 publications

(8 citation statements)

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“…SS-MC-MA provides frequency diversity keeping the bit rate constant, however it suffers from self-spreaded symbols interference. Results, shown in References [8] and [9] proved the viability of HF interactive digital voice links with low signal-to-noise ratios by means of in-band spreading, reduced channel coding and no interleaving. The absence of time diversity is supplied by SS-MC-MA, where the serial symbols are transmitted over the whole band so the information affected by deep-nulls can be restored by the unaffected carriers.…”

Section: Data Modem Designmentioning

confidence: 99%

“…Since the presentation of References [8,9], two different decisions have been taken in order to cope better with MAI. On one hand, two new different MUD techniques have been applied to the design.…”

Section: Data Modem Designmentioning

confidence: 99%

“…Furthermore, once the transmission scheme has demonstrated to be efficient, complementary analysis, relaxing delay constraint for data transmission [8], is a promising path to achieve new goals. This operation mode will increase data rate, by the increase of the constellation size and the use of combined interleaving and channel coding strategies.…”

Section: Conclusion and Future Research Linesmentioning

confidence: 99%

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Validation of a HF spread spectrum multi‐carrier technology through real‐link measurements

Santana-Sosa

Zazo-Bello

Álvarez

et al. 2006

Trans Emerging Tel Tech

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SUMMARYThe HF band data communication link has been traditionally desired by many of the large range transmission systems although it is associated to unfavourable performances as low transmission rate, large delay and low confidence in terms of link establishment and maintenance. Although transmission rates may be high enough to transmit digital voice, delay, usually over several seconds, has been the main handicap to let the systems provide interactive digital voice links. Indeed, there is no unclassified equipment with this capability. The main achievement of this proposal is that we are able to guarantee digital voice transmission with low latency, around 135 ms (modem þ codec), providing a full interactive digital voice link. Performances of two new 2460 bps HF modems are presented versus the 39-tone 2400 bps MIL-STD-188-110A modem, working over an ITU-R moderate channel. Furthermore, these results are corroborated by real tests carried out in a 1800 Km link in the 18 MHz band.

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Section: Data Modem Designmentioning

confidence: 99%

Section: Data Modem Designmentioning

confidence: 99%

Section: Conclusion and Future Research Linesmentioning

confidence: 99%

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Validation of a HF spread spectrum multi‐carrier technology through real‐link measurements

Santana-Sosa

Zazo-Bello

Álvarez

et al. 2006

Trans Emerging Tel Tech

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“…Each sub-carrier transports only part of a symbol, so that even if it suffers a disastrous attenuation, such symbol may possible be recovered by joint contribution of surviving sub-carriers. Multiple Access Interference (MAI) is a spreading disadvantage, usually requiring Multiple User Detectors (MUD) at receiver [3] [4].…”

Section: Coding Techniques Without Channel Sate Informationmentioning

confidence: 99%

Multi-Carrier Techniques Performance on Ionospheric Channel for Delay-Sensitive Applications

López-Pérez

Zazo-Bello²,

Álvarez

et al. 2007

MILCOM 2007 - IEEE Military Communications Conference

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Multi-carrier modulations are widely employed in HF communications, and particularly OFDM, mainly because their ease of generation by means of DFT and also their appealing properties that can turn a selective fading channel into a set of flat channels. In order to cope with deep nulls in the channel traditional approach has been the use of channel coding and interleaving, thus causing an increase in communication delay. For delay-sensitive applications, spreading schemes over OFDM, such as OFDM-CDM can be applied. If CSI is known at transmitter, system performance can be improved by BER-optimum power loading and channel matrix SVD decomposition of OFDM-CDM signal. These techniques are well suited to delay-sensitive applications as they incur in no further delays.

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“…SS-MC-MA techniques provide a robust mechanism to avoid the effects of the deep-nulls introduced by the channel (Figure 1) without the need of powerful coding and long interleaving. Work showed in [14] and [11] firstly introduced these techniques in this kind of systems and demonstrated, in a simple simulated environment, that SS-MC-MA is a valid technique to provide interactive digital voice communications over ionospheric links. Using SS-MC-MA, the serial symbols are transmitted over all frequencies so the information affected by deep-nulls can be restored with the unaffected carriers using frequency diversity mechanism.…”

Section: Ss-mc-ma Techniquesmentioning

confidence: 99%

Real-link Performance of a SS-MC-MA High Frequency Radio Modem

Santana-Sosa

Raos

Zazo-Bello

et al. 2006

Multi-Carrier Spread-Spectrum

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The HF band data communication link has been traditionally desired by many of the large range transmission systems although it is associated to unfavorable performances as low transmission rate, large delay and low confidence in terms of link establishment and maintenance. Although transmission rates may be high enough to transmit digital voice, delay, usually over several second, has been the main handicap to let the systems provide interactive digital voice links. Indeed, there is no unclassified equipment with this capability. The main achievement of this proposal is that we are able to guarantee digital voice transmission with low latency, around 135 msec (modem+codec), providing a full interactive digital voice link. Performances of two new 2460 bps. HF modems are presented versus the 39-tone 2400 bps MIL-STD-188-110A modem, working over an ITU-R moderate channel. Futhermore, these results are corroborated by real tests carried out in a 1800 Km. link.

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Performance of an OFDM-CDMA HF modem

Cited by 6 publications

References 0 publications

Validation of a HF spread spectrum multi‐carrier technology through real‐link measurements

Validation of a HF spread spectrum multi‐carrier technology through real‐link measurements

Multi-Carrier Techniques Performance on Ionospheric Channel for Delay-Sensitive Applications

Real-link Performance of a SS-MC-MA High Frequency Radio Modem

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