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A polar quantizer is presented for detection and quantization of modulated signals in cellular applications. It consists of amplitude and phase quantizers. A time-to-digital converter (TDC) is designed to measure and quantize the phase, while a typical ADC is used for amplitude quantization. Polar quantizer significantly reduces the sensitivity of the quantizer to amplitude resolution. The 10 bit...
In a passive ultra high frequency radio frequency identification (UHF RFID) system, the reverse link (tag to reader) transmission is realized by the backscattering approach. Traditional UHF RFID readers use the same carrier frequency for both the forward and reverse links. In this paper, a UHF RFID reader that uses different central frequencies for the forward and reverse links is presented. Since...
Bandwidth allocation for multi-user sharing heterogeneous wireless access networks is one of the most important problems in the next generation wireless networks. In this paper, we propose a bandwidth allocation scheme named as Efficient and Fair Rate Allocation (EFRA), which is formulated as a convex optimization problem maximizing the user's utility as well as determining to split the total rate...
In this paper, we propose a cross-layer model to provide reliable video stream transmission in the mobile environment. In the proposed model, the application-layer forward error correction (A-FEC) parameters at the application layer, the ARQ parameters at the data link layer and the adaptive modulation and coding parameters at the physical layer are jointly designed. By maximizing the number of correctly...
Since data gathering is the primary functionality of sensor networks, it is crucial to provide an appropriate method for information collecting in the face of limited energy challenge. While conventional protocols are inclined to take decreasing the end-to-end delay and minimizing the total energy consumption into consideration. In this paper, we discuss an existing Fast Low-cost Shortest Path Tree...
Long-haul traffic accounts for a large percentage of the total data carried on the Internet. Due to the rapid changes of the Internet in terms of access technologies and core network bandwidth, the performance of long-haul transmission in the current Internet environment has not been well understood. In our research, we chose three typical long-haul paths (national, international yet continental,...
To provide reliable video stream transmission over wireless networks, we propose a cross-layer design model in this paper. In the proposed model, the adaptive modulation and coding parameters at the physical layer, the ARQ parameters at the data link layer and the application-layer forward error correction (A-FEC) parameters at the application layer are jointly designed. Our objective is to maximize...
The throughput capacity of wireless ad hoc networks is derived when the traffic is heterogeneous but the node distribution is homogeneous. For the heterogeneous traffic we consider two types of traffic in the network, namely, unicast and data gathering communications. There are k sources that send different data to a single node and the rest of n-k nodes in the network participate in unicast communications...
We study the scaling laws for wireless ad hoc network in which the distribution of nodes in the network is homogeneous but the traffic is heterogeneous. More specifically, we consider the case in which a node is the sink to k sources sending different information, while the rest of the nodes are part of unicast communications with a uniform assignment of source-destination pairs. We prove that the...
This paper presents a message-streams oriented hybrid slot allocation protocol (MOHSAP) for tactical data link system that combines a collision-free static slot allocation algorithm and a contention based dynamic slot allocation algorithm while retaining the advantages of each. For fixed message streams (FMS), this contains the key information generally in tactical data link system, MOHSAP assigns...
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