Adaptive Modulation and Multiple Access for the OFDM Transmission Technique
Wireless Personal Communications: An International Journal
A New Adaptive Transmission Scheme for Wireless Communication SystemsUtilizing Frequency Diversity
Wireless Personal Communications: An International Journal
A Quantitative Comparison of Ad Hoc Routing Protocols with and without Channel Adaptation
IEEE Transactions on Mobile Computing
Closed-loop architecture and protocols for rapid dynamic spreading gain adaptation in CDMA networks
IEEE/ACM Transactions on Networking (TON)
EURASIP Journal on Applied Signal Processing
Adaptive rate controller for mobile ad hoc networks
International Journal of Mobile Communications
Efficient and fast retransmission for wireless networks
Computer Communications
On the throughput gain for rapid dynamic symbol duration adaptation within discrete duration sets
ISCIT'09 Proceedings of the 9th international conference on Communications and information technologies
Cross-Layer Design for MRT Systems with Channel Estimation Error and Feedback Delay
Wireless Personal Communications: An International Journal
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We propose a new adaptive modulation technique for simultaneous voice and data transmission over fading channels and study its performance. The proposed scheme takes advantage of the time-varying nature of fading to dynamically allocate the transmitted power between the inphase (I) and quadrature (Q) channels. It uses fixed-rate binary phase shift keying (BPSK) modulation on the Q channel for voice, and variable-rate M-ary amplitude modulation (M-AM) on the I channel for data. For favorable channel conditions, most of the power is allocated to high rate data transmission on the I channel. The remaining power is used to support the variable-power voice transmission on the Q channel. As the channel degrades, the modulation gradually reduces its data throughput and reallocates most of its available power to ensure a continuous and satisfactory voice transmission. The scheme is intended to provide a high average spectral efficiency for data communications while meeting the stringent delay requirements imposed by voice. We present closed-form expressions as well as numerical and simulation results for the outage probability, average allocated power, achievable spectral efficiency, and average bit error rate (BER) for both voice and data transmission over Nakagami-m fading channels. We also discuss the features and advantages of the proposed scheme. For example, in Rayleigh fading with an average signal-to-noise ratio (SNR) of 20 dB, our scheme is able to transmit about 2 bits/s/Hz of data at an average BER of 10 -5 while sending about 1 bit/s/Hz of voice at an average BER of 10-2