Somsak Kittipiyakul

• PhD
• Professor (Assistant) at Sirindhorn International Institute of Technology (SIIT)

Electricity demand forecasting plays a significant role in energy markets. Accurate prediction of electricity demand is the key factor in optimizing power generation and consumption, saving energy resources, and determining energy prices. However, integrating energy mix scenarios, including solar and wind power, which are highly nonlinear and seaso...

Electricity demand forecasting plays a significant role in energy markets. Accurate prediction of electricity demand is the key factor to optimize power generation, consumption, saving energy resources, and determining the energy prices. However, integrating energy mix scenarios, including solar and wind power which are highly non-linear and season...

As short-term load forecasting is essential for the day-today operation planning of power systems, we built an ensemble learning model to perform such forecasting for Thai data. The proposed model uses voting regression (VR), producing forecasts with weighted averages of forecasts from five individual models: three parametric multiple linear regres...

Today, renewable energy resources are a critical component of distributed energy systems. However, their intermittent nature makes them unstable energy sources, making them very difficult to use optimally in any energy system. Battery storage is a viable solution for this issue. In this paper, we consider distributed power-flow assignment consistin...

Accurate electricity demand forecasting for a short horizon is very important for day-to-day control, scheduling, operation, planning, and stability of the power system. The main factors that affect the forecasting accuracy are deterministic variables and weather variables such as types of days and temperature. Due to the tropical climate of Thaila...

The ubiquitous coverage/connectivity requirement of wireless cellular networks has shifted mobile network operators’ (MNOs) interest toward dense deployment of small cells with coverage areas that are much smaller as compared to macrocell base stations (MBSs). Multi-operator small cells could provide virtualization of network resources (infrastruct...

Safety message verification plays an important role in securing vehicular ad hoc networks (VANETs). As safety messages are broadcasted several times per second in a highly dense network, message arrival rate can easily exceed the verification rate of safety messages at a vehicle. As a result, an algorithm is needed for selecting and prioritizing re...

The accuracy of short term electricity demand forecasting is essential for operation and trading activities on energy market. This paper considers a parsimonious forecasting model to explain the importance of sophisticated weather parameters for hourly electricity demand forecasting. Temperature is the major factor that directly influence electrici...

The paper presents a game theoretic solution for distributed subchannel allocation problem in small cell networks (SCNs) analyzed under the physical interference model. The objective is to find a distributed solution that maximizes the welfare of the SCNs, defined as the total system capacity. Although the problem can be addressed through best-resp...

In high-density road networks, with each vehicle broadcasting multiple messages per second, the arrival rate of safety messages can easily exceed the rate at which digital signatures can be verified. Since not all messages can be verified, algorithms for selecting which messages to verify are required to ensure that each vehicle receives appropriat...

The quality of short-term electricity demand forecasting is essential for the energy market players for operation and trading activities. Electricity demand is significantly affected by non-linear factors, such as climatic conditions, calendar components and seasonal behavior, which have been widely reported in the literature. This paper considers...

This paper proposes multi-equation linear regression model with autoregressive AR(2) method for modelling and forecasting a day ahead electricity load. AR(2) is used to show the dependency of next data on its previous two days data because the nature of electricity load consumption for the next day follow the pattern of previous days. Since, we all...

Public transportation is a popular means of travel for many urban residents. However, users may not know the location and number of people on a vehicle, which results in uncertainty and wasted time while waiting. To help users manage their time more efficiently, a passenger estimation system that can provide the location and occupancy of each vehic...

We study a distributed channel allocation problem of non-cooperative OFDMA femtocells in two-tiered macro-femto networks. The objective is to maximize the total capacity of uplink macro users and femto users. We assume a time-slotted system, a time-invariant channel model (no fading), each user knows the signal-to-interference-plus-noise ratio (SIN...

In this paper, we provide a simulation-based framework to estimate the electricity cost of cooling and lighting systems in horticulture for a given desired average temperature setting. Since the electricity price follows a Time-of-Use (TOU) pricing program which asks for a higher price during the peak period, the electricity cost could be reduced b...

We study impacts of electric vehicle (EV) home chargers on a typical three-phase distribution transformer (DTR) in distribution grid. We focus on the DTR loading and voltage imbalance. We focus on the distribution grid operated by the Provincial Electricity Authority (PEA), which is a major utility provider in Thailand. We determine the maximum num...

A contention-based forwarding is a popular approach for forwarder selection in wireless vehicular ad hoc networks. Requiring no information of neighbors, the selection depends on distance-based defer time where the furthest node rebroadcasts first while the others suppress their rebroadcasting after receiving duplicate message within their defer ti...

In this paper, we propose a new time-stable geocast protocol, called iDTSG, for post crash notification in vehicular highway networks. iDTSG is an improvement of the existing DTSG protocol. From ns-3 simulation with realistic channel model and vehicle mobility model, iDTSG achieves almost 100% delivery ratio, similar to DTSG, but at a much lower co...

In this paper, a many-sources large deviations principle (LDP) for the transient workload of a multiqueue single-server system is established where the service rates are chosen from a compact, convex, and coordinate-convex rate region and where the service discipline is the max-weight policy. Under the assumption that the arrival processes satisfy...

We study interaction between gradient-based subcarrier allocation algorithms and TCP traffic sources in a downlink single-hop OFDMA wireless system. Specifically, we are interested in evaluating the maximum-rate (Max-SNR), Proportional Fair (PF), and queue-based Max-Weight (QBMW) subcarrier schedulers, in both non-iterative and iterative versions,...

We consider a downlink OFDMA subcarrier allocation problem where the allocation algorithms are gradient-based but only CSI for some subet of subcarriers from each user is available at the transmitter. We propose an iterative version of gradient-based OFDMA subcarrier allocation schedulers which performs better than the standard non-iterative gradie...

We perform a performance evaluation of ZigBee mesh networks based on XBee modules, in terms of packet delay and received signal strength (RSSI). We evaluate the performance for both line-of-sight (LOS) and non-line-of-sight (NLOS) environments in buildings and a parking lot. The results of our study are useful for building wireless sensor networks...

This paper considers the problem of optimal server allocation in a time-slotted system with N statistically symmetric queues and K servers when the arrivals and channels are stochastic and time-varying. In this setting, we identify two classes of "desirable" policies with potentially competing goals of maximizing instantaneous throughput versus bal...

This work analyzes the high-SNR asymptotic error performance of outage-limited communications with fading, where the number of bits that arrive at the transmitter during any timeslot is random but the delivery of bits at the receiver must adhere to a strict delay limitation. Specifically, bit errors are caused by erroneous decoding at the receiver...

In this paper, we establish a many-sources large deviations principle (LDP) for the stationary workload of a multi-queue single-server system with simplex capacity, operated under a stabilizing and non-idling maximum-weight scheduling policy. Assuming a many-sources sample path LDP for the arrival processes, we establish an LDP for the workload pro...

This work analyzes the high-SNR asymptotic error performance of outage-limited communications with fading, where the number of bits that arrive at the transmitter during any time slot is random but the delivery of bits at the receiver must adhere to a strict delay limitation. Specifically, bit errors are caused by erroneous decoding at the receiver...

PhD Defense Presentation

This work analyzes the high-SNR asymptotic error performance when the number of bits that arrive at the transmitter during any time slot is random, the channel experiences outage, and the delivery of bits at the receiver must adhere to a strict delay limitation. It is shown that for a class of arrival processes whose burstiness scales down linearly...

Multiple antennas at the transmitters and receivers in a multiple access channel (MAC) can provide simultaneous diversity, spatial multiplexing, and space-division multiple access gains. The fundamental tradeoff in the asymptotically large SNR regime is shown by Tse et al. (2004). On the other hand, MAC scheduling can provide a statistical-multiple...

We construct cooperative diversity coding schemes that mitigate the effects of symbol asynchronicity among network users. We do so by modifying, at the expense of implementation practicality, the signaling complexity of well behaved existing schemes. The modification allows the same good performance (DMT optimality) in the presence of synchronicity...

This paper considers the issue of delay optimal subcarrier allocation in OFDMA wireless networks when the arrivals and channels are stochastic. Our objective is to minimize the long-term average packet delay over multiple time epochs. In previous studies, we have shown that the optimal policy is complicated and unknown. However, based on the insigh...

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1996. Includes bibliographical references (p. 99-100). by Somsak Kittipiyakul. M.Eng.

This work investigates the asymptotic error performance of outage-limited communications in cooperative wireless relay networks, with fading that is quasi-static, with an information-arrival process that is stochastic and bursty, and with bits that have a strictly limited lifespan. Employing large-deviation techniques, we analyze the probability of...

The work analyzes the error performance of high-SNR, high-rate, point-to-point, outage-limited, wireless communications, with bursty and delay-limited information. In this setting, the bit-arrival process is stochastic and bursty, and the bits are limited by a strict delay condition. In the presence of fixed transmission rate, errors are due to bot...

This paper considers a problem of scheduling and cluster size with N i.i.d. source nodes trying to transmit data to a common destination node (e.g. a gateway or a processing center), with the help of some subset of nodes in the form of relays. The source nodes share the network in a TDM manner, using a round-robin scheduling scheme. There are two c...

We consider a system with a bursty and delay-sensitive data source to be transmitted over a constant-rate MIMO channel with no CSI information at the transmitter. Given the diversity-multiplexing tradeoff region of the MIMO channel, we find the optimal multiplexing rate that optimizes the end-to-end loss probability. Based on the effective bandwidt...

This paper considers the issue of optimal subcarrier allocation in OFDMA. We show, via a counter example, that water-filling based subcarrier allocation policies, contrary to conventional wisdom, fail to provide rate-stability for an otherwise stabilizable OFDMA system. Water-filling is too myopic when considering long-time average performance, e.g...

This paper considers the issue of optimal subcarrier allocation in OFDMA. When including time-varying packet arrivals and channels, we show, via a counter example, that water-filling-based subcarrier allocation policies, contrary to conventional wisdom, fail to provide rate-stability for an otherwise stabilizable OFDMA system. We briefly discuss th...

The MIT remote microscope is a telemicroscopy system that allows users to remotely control and view a microscope over the internet with a graphical interface that runs on an ordinary workstation computer. The microscope server consists of an automated Zeiss microscope that is controlled by a personal computer, while the client interface is implemen...

The medium access control protocol of IEEE 802.11 networks has been extensively studied to explore its throughput performance. A popular regime of study is the saturation regime where users are assumed to be saturated with information bits. The throughput achieved in this regime, called the saturation throughput, is commonly interpreted as the maxi...

This paper considers the issue of optimal subcarrier alloca tion in OFDMA wireless networks when the arrivals and channels are stochastic and time-varying. Our objective is to minimize the long-term average packet delay over multiple time epochs. We show by an example that water-fillin g-based subcarrier allocation policy which maximizes throughput...

This paper presents an embedded wireless sensor network (WSN) prototype system for temperature monitoring in a building. This network will be used for management of air conditioning systems at SIIT. The ultimate goal is to help saving the energy cost and reducing energy consumption. The system provides a web user interface for any user to access th...