Seong‐Jun Oh

In this paper, we consider a direct-sequence code division multiple access (DS-CDMA) network consisting of a single radio access point and a collection of wireless terminals. The network offers two classes of service: class-1 (real-time) and class-2 (reliable). We are interested in studying the effect of dynamic spreading gain control (SGC) on the dynamics of multiple access interference (MAI), spectral efficiency, and the quality of service (QoS) experienced by each service class. We first cons

This paper addresses the problem of dynamic resource allocation in a multiservice direct-sequence code-division multiple-access (DS-CDMA) wireless network supporting real-time (RT) and nonreal-time (NRT) communication services. For RT users, a simple transmission power allocation strategy is assumed that maximizes the amount of capacity available to NRT users without violating quality of service requirements of RT users. For NRT users, a joint transmission power and spreading gain (transmission

We study the radio resource allocation problem of distributed joint transmission power control and spreading gain allocation in a DS-CDMA mobile data network. The network consists of K base stations and M wireless data users. The data streams generated by the users are treated as best-effort traffic, in the sense that there are no pre-specified constraints on the quality of the radio channels. We are interested in designing a distributed algorithm that achieves maximal (or near-maximal in some r

Article Optimality of greedy power control and variable spreading gain in multi-class CDMA mobile networks Share on Authors: Seong-Jun Oh Electrical Engineering and Computer Science Department, University of Michigan, 1301 Beal Ave., Ann Arbor, MI Electrical Engineering and Computer Science Department, University of Michigan, 1301 Beal Ave., Ann Arbor, MIView Profile , Kimberly M. Wasserman Electrical Engineering and Computer Science Department, University of Michigan, 1301 Beal Ave., Ann Arbor,

The information-theoretic sum capacity of reverse link CDMA systems with QoS constraints is investigated in this paper. Since the reverse link of CDMA systems are, for a given channel and noise conditions, interference-limited, the sum capacity can be achieved by optimally allocating the transmit powers of the mobile stations with the optimal (Shannon) coding. Unfortunately, the sum capacity is usually achieved via unfair resource allocation. This can be avoided by imposing QoS constraints on th

In this paper, we consider a DS-CDMA mobile network supporting real-time and non-real-time services. We study how the delay tolerance of non-real-time traffic can be exploited by allowing both transmission power control and variable spreading gain (transmission rate) control. Two control mechanisms adapt the received energy per bit to the current channel conditions and efficiently manage the multiple access interference so as to optimize performance. We provide the jointly optimal power and spre

Signal scattering in the troposphere is a phenomenon referred to as “troposcatter”, and it is promising method for wireless communication beyond the line of sight (b-LOS). For a troposcatter communication system, it is important to develop a channel model for the tropospheric scatter. Recently, b-LOS communication using troposcatter received much attention for its application to military communication. Thus, a comprehensive review and analysis of conventional ITU-R troposcatter propagation model

Obesity is a global health problem that affects the quality of life. It is a multidimensional chronic risk factor for major medical conditions, such as cardiovascular diseases, diabetes, and cancer. This clinical trial evaluated the efficacy of Lactobacillus sakei OK67 (DW2010), a lactic acid bacterium, in reducing body and visceral fat in overweight individuals (body mass index ≥25 kg/m2 and <30 kg/m2), aged 20–60 years. A total of 100 subjects placed in a lifestyle modification program were

The information-theoretic sum capacity of reverse link CDMA systems is investigated in this paper. As the reverse link CDMA systems are interference-limited, for given channel and noise conditions, the information-theoretic system capacity can be achieved by optimally managing the interference from mobile stations. Optimal interference management means optimal allocation of the transmit powers of the mobile stations. The exhaustive search of the optimal power allocation policy that maximizes the

The information-theoretic sum capacity of reverse link CDMA systems is investigated in this paper. As the reverse link CDMA systems are interference-limited, for given channel and noise conditions, the information-theoretic system capacity can be achieved by optimally allocating the transmit powers of the mobile stations. The maximum capacity is often achieved by unfair resource allocation. To avoid such a case, QoS constraints are imposed to individual mobile stations. The exhaustive search of

Object tracking by an acoustic sensor based on particle filtering is extended for the tracking of multiple objects. In order to overcome the inherent limitation of the acoustic sensor for the simultaneous multiple object tracking, support from the visual sensor is considered. Cooperation from the visual sensor, however, is better to be minimized, as the visual sensor's operation requires much higher computational resources than the acoustic sensor-based estimation, especially when the visual sen

An approach for dynamic object association and identification is proposed for heterogeneous sensor network consisting of visual and identification sensors. Visual sensors track objects by a 2D localization, and identification sensors (i.e., RFID system, fingerprint, or iris recognition system) are incorporated into the system for object identification. This paper illustrates the feasibility and effectiveness of information association between the position of objects estimated by visual sensors a

In this paper we investigate the HDR CDMA system reverse link data channel throughput and obtain both an upper bound, which is derived from the pole capacity, and more practical results applicable when considering variable rate transmission with probabilistic flow control. From the analytical derivation of the pole capacity, a simple but effective rate control algorithm is devised that maintains the reverse link outage probability below a desired level while attempting at maximizing the reverse