In this paper we introduce a test through which the responsiveness of a TCP aggregate can be measured. The first introduced test is based on dropping a few packets from the aggregate and measuring the resulting rate decrease of that aggregate. This kind of test is not robust to multiple simultaneous tests performed at different routers. Extensions are done to make the test robust to multiple si...

In a paper by Cavallini et al., chip-level differential encoding/detection for direct-sequence spread-spectrum signals was proposed to cope with frequency-nonselective fast fading channels. It was shown that, unlike in the additive white Gaussian noise channel, in time-varying fading channels the system performance may be considerably improved, especially when the spreading factor is increased....

Recent theoretical results show that use of chaotic dynamics can significantly increase privacy of digital communication signals. The purpose of this paper is to report sea trial results of a chaotic spread spectrum system. Due to its ability to simultaneously sharing the same frequency band for various users (through Code Division Multiple Access) and its robustness against channel imperfectio...

Nearly all previous analytical results on the performance of direct-sequence spread-spectrum multiple-access (DS/SSMA) communication systems are restricted to systems in which the periodp of the signature sequence is equal to the number N of chips per data symbol. In many applications, however, it is necessary to employ signature sequences whose periodp is much larger than N. Thus, successive N...

Information theoret ic aspects of C o d e Division Mult iple Access ( C D M A ) r a n d o m directsequence spread-spectrum (DSSS) are investigated. T h e CDMA-DSSS channel wi th randomly a n d independent ly chosen spreading sequences accurately models the s i tuat ion where pseudo-noise sequences span many symbol per iods. We analyze t h e spec t ra l efficiency ( total capaci ty p e r chip) a...

ln this paper, we obtain the optimum transmission ranges to maximize throughput for a direct-sequence spread-spectrum multihop packet radio network. In the analysis, we model the network selfinterference as a random variahle which is equal to the sum of the interference power of all other terminals plus hackground noise. The model is applicable to other spread spectrum schemes where the interfe...

Direct sequence spread spectrum (DSSS) techniques for low probability of intercept (LPI) and multi-user communications applications for underwater acoustic communications are investigated. Two promising receivers, a RAKE based receiver and a hypothesis-feedback equalization based architecture are considered. The performance of the proposed receiver structures are compared based on simulations a...

The FHSS and DSSS technologies are described as well as different types of spread coding. DSSS systems can provide higher access data rates (up to 11Mbit/s) than FHSS systems (up to 3Mbit/s). More FHSS systems can operate simultaneously in the same area than DSSS systems. DSSS systems have higher interference susceptibility tolerance levels. However, if there is a strong broadband interferer in...

Absrract-Upper and lower bounds on the average probability of error are obtained for direct-sequence spread-spectrum multipleaccess communications systems with additive white Gaussian noise channels. The bounds, which are developed from convexity properties of the error probability function, are valid for systems in which the maximum multiple-access interference does not exceed the desire...

In this paper, we introduce a strong adversarial attack, referred to as the flipping attack, on Direct-Sequence Spread Spectrum (DSSS) systems. In this attack, the attacker, which is appropriately positioned between the transmitter and the receiver, instantaneously flips the transmitted symbols in the air at 50% rate, thereby driving the channel capacity to zero. Unlike the traditional jamming ...