Abstract: Worldwide Interoperability for Microwave Access, is a broadband technology, which can effectively transmit a data across a group of users using Multicast and Broadcast Service. WiMAX belongs to a family of (IEEE 802.16) standards and is evolving as a fourth generation technology. WiMAX is the next generation technology that offers wireless access over long distances. MBS zone, which is a group of base stations that are broadcasting the same multicast packets which defines Multicast and Broadcast services. Handover is a process of transferring an ongoing call or data session from one channel connected to the core network to another channel. The handover causes authentication, delay, packet loss, jitter that mainly affects the communication. In this paper, we present a survey on handover security issues in WiMAX.
Abstract: IEEE 802.16 (WiMAX) aims to present high speed
wireless access to cover wide range coverage. The base station (BS)
and the subscriber station (SS) are the main parts of WiMAX.
WiMAX uses either Point-to-Multipoint (PMP) or mesh topologies.
In the PMP mode, the SSs connect to the BS to gain access to the
network. However, in the mesh mode, the SSs connect to each other
to gain access to the BS.
The main components of QoS management in the 802.16 standard
are the admission control, buffer management and packet scheduling.
In this paper, we use QualNet 5.0.2 to study the performance of
different scheduling schemes, such as WFQ, SCFQ, RR and SP when
the numbers of SSs increase. We find that when the number of SSs
increases, the average jitter and average end-to-end delay is increased
and the throughput is reduced.
Abstract: Different order modulations combined with different
coding schemes, allow sending more bits per symbol, thus achieving
higher throughputs and better spectral efficiencies. However, it must
also be noted that when using a modulation technique such as 64-
QAM with less overhead bits, better signal-to-noise ratios (SNRs) are
needed to overcome any Inter symbol Interference (ISI) and maintain
a certain bit error ratio (BER). The use of adaptive modulation allows
wireless technologies to yielding higher throughputs while also
covering long distances. The aim of this paper is to implement an
Adaptive Modulation and Coding (AMC) features of the WiMAX
PHY in MATLAB and to analyze the performance of the system in
different channel conditions (AWGN, Rayleigh and Rician fading
channel) with channel estimation and blind equalization. Simulation
results have demonstrated that the increment in modulation order
causes to increment in throughput and BER values. These results
derived a trade-off among modulation order, FFT length, throughput,
BER value and spectral efficiency. The BER changes gradually for
AWGN channel and arbitrarily for Rayleigh and Rician fade
channels.
Abstract: WiMAX is a telecommunications technology and it is
specified by the Institute of Electrical and Electronics Engineers Inc.,
as the IEEE 802.16 standard. The goal of this technology is to
provide a wireless data over long distances in a variety of ways. IEEE
802.16 is a recent standard for mobile communication. In this paper,
we provide an overview of various key management algorithms to
provide security for WiMAX.
Abstract: Cognitive Radio is a turning out technology that
empowers viable usage of the spectrum. Energy Detector-based
Sensing is the most broadly utilized spectrum sensing strategy.
Besides, it's a lot of generic as receivers doesn't would like any
information on the primary user's signals, channel data, of even the
sort of modulation. This paper puts forth the execution of energy
detection sensing for AM (Amplitude Modulated) signal at 710 KHz,
FM (Frequency Modulated) signal at 103.45 MHz (local station
frequency), Wi-Fi signal at 2.4 GHz and WiMAX signals at 6 GHz.
The OFDM/OFDMA based WiMAX physical layer with
convolutional channel coding is actualized utilizing USRP N210
(Universal Software Radio Peripheral) and GNU Radio based
Software Defined Radio (SDR). Test outcomes demonstrated the
BER (Bit Error Rate) augmentation with channel noise and BER
execution is dissected for different Eb/N0 (the energy per bit to noise
power spectral density ratio) values.
Abstract: In this paper a novel ultra-wideband (UWB) slot antenna with band notch characteristics for world interoperability for microwave access (WiMAX) is proposed. The designed antenna consists of a rectangular radiating patch and a ground plane with tapered shape slot. To realize a notch band, a curved parasitic element has been etched out along with the radiating patch. It is observed that by adjusting the length, thickness and position of the parasitic element, the proposed antenna can achieved an impedance bandwidth of 8.01GHz (2.84 to 10.85GHz) with a notched band of 3.28-3.85GHz. Compared to the recently reported band notch antennas, the proposed antenna has a simple configuration to realize band notch characteristics in order to mitigate the potential interference between WiMAX and UWB system. Furthermore, a stable radiation pattern and moderate gain except at the notched band makes the proposed antenna suitable for various UWB applications.
Abstract: In this paper, an overview of the radio over fiber (RoF) technology is provided. Obstacles for reducing the capital and operational expenses in the existing systems are discussed in various perspectives. Some possible RoF deployment scenarios for WiMAX
data transmission are proposed as a means for capital and operational
expenses reduction. IEEE 802.16a standard based end-to-end physical layer model is simulated including intensity modulated direct detection RoF technology. Finally the feasibility of RoF
technology to carry WiMAX signals between the base station and the
remote antenna units is demonstrated using the simulation results.
Abstract: A simple network model is developed in OPNET to
study the performance of the Wi-Fi protocol. The model is simulated
in OPNET and performance factors such as load, throughput and delay
are analysed from the model. Four applications such as oracle, http, ftp
and voice are applied over the Wireless LAN network to determine the
throughput. The voice application utilises a considerable amount of
bandwidth of up to 5Mbps, as a result the 802.11g standard of the
Wi-Fi protocol was chosen which can support a data rate of up to
54Mbps. Results indicate that when the load in the Wi-Fi network is
increased the queuing delay on the point-to-point links in the Wi-Fi
network significantly reduces until it is comparable to that of WiMAX.
In conclusion, the queuing delay of the Wi-Fi protocol for the network
model simulated was about 0.00001secs comparable to WiMAX
network values.
Abstract: WiMAX is defined as Worldwide Interoperability for
Microwave Access by the WiMAX Forum, formed in June 2001 to
promote conformance and interoperability of the IEEE 802.16
standard, officially known as WirelessMAN. The attractive features
of WiMAX technology are very high throughput and Broadband
Wireless Access over a long distance. A detailed simulation
environment is demonstrated with the UGS, nrtPS and ertPS service
classes for throughput, delay and packet delivery ratio for a mixed
environment of fixed and mobile WiMAX. A simple mobility aspect
is considered for the mobile WiMAX and the PMP mode of
transmission is considered in TDD mode. The Network Simulator 2
(NS-2) is the tool which is used to simulate the WiMAX network
scenario. A simple Priority Scheduler and Weighted Round Robin
Schedulers are the WiMAX schedulers used in the research work
Abstract: The direct implementation of interleaver functions
in WiMAX is not hardware efficient due to presence of complex
functions. Also the conventional method i.e. using memories for
storing the permutation tables is silicon consuming. This work
presents a 2-D transformation for WiMAX channel interleaver
functions which reduces the overall hardware complexity to
compute the interleaver addresses on the fly. A fully reconfigurable
architecture for address generation in WiMAX
channel interleaver is presented, which consume 1.1 k-gates in
total. It can be configured for any block size and any modulation
scheme in WiMAX. The presented architecture can run at a
frequency of 200 MHz, thus fully supporting high bandwidth
requirements for WiMAX.
Abstract: In this paper an average number of re-handlings
analysis is proposed to solve the problem of finding bays
configuration in small container terminal in Gliwice, Poland.
Rehandlings in this terminal can be performed only by reachstackers.
The goal of the heuristic is to plan the reachstacter moves in the
terminal, assuming that the target containers are reached and the
number of re-handings is minimized. The real situation requires also
to take into account the model of the problem environment
uncertainty caused by the fact that many containers are not delivered
to the terminal on time, or can not be sent on scheduled time. To
enable this, the heuristic uses some assumptions to simplify problem
analysis.