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A scalable video delivery transmission framework over MIMO OFDM wireless channels by combining power allocation and antenna selection scheme has been proposed. The framework consisting of independently decodable layers (3D ESCOT), UEP channel coding structure, and antenna selection scheme provide more system error resilience even during deep fading period in wireless channels. A new algorithm is proposed...
There are a few core technologies to enable high-performance 4th generation (4G) broadband wireless communication system. A multiple input multiple output (MIMO) provides high-rate transmission through expended channels by multiple array antennas in both sender and receiver side. Also orthogonal frequency division multiplexing (OFDM) is well-known as the most appropriate technique for high data rate...
Recently, Li, Hwu and Ratazzi have proposed a physical-layer security design to guarantee low probability of interception (LPI) for MIMO systems without relying on upper layer data encryption. The proposed scheme utilizes antenna array redundancy to deliberately randomize the transmitted signals to prevent eavesdropping. Motivated by their idea, in this paper we design a physical-layer transmission...
The high-data rate links in broadband wireless communications are being essential for a constant growth in the tough environment of radio transmissions, and orthogonal frequency division multiplexing (OFDM) can deal with these circumstances. Coded OFDM (COFDM) research in wireless communications is a concept of the well-use spectrum for robust high-data rate transmissions, and its regulation in the...
In this paper, we study the effect of various concatenated forward error correction (FEC) codes on the performance of a wireless orthogonal frequency division multiplexing (OFDM) system. In FEC concatenated channel code, the OFDM system incorporates Reed-Solomon (RS) encoder of (255,239,8), Cyclic Encoder of (15,11), Bose-Chadhuri-Hocquenghem (BCH) encoder of (127,64) with Convolution encoder of 2...
MIMO-OFDM wireless systems require adaptive modulation and coding based on channel state information (CSI) to maximize throughput in changing wireless channels. Traditional adaptive modulation and coding attempts to predict the best rate available by estimating the packet error rate for each modulation and coding scheme (MCS) by using CSI, which has shown to be challenging. This paper considers supervised...
This paper deals with the problem of finding an optimal subcarrier allocation strategy for uplink and downlink communications in an OFDMA metropolitan wireless system. In particular a two steps approach is considered; at the first step the scheduler establishes the amount of resources to assign to users on the basis of their quality of service (QoS) constraints, while, at the second step, channel...
This paper proposes a new systematic design framework called DBOASTBC-OFDM for wideband wireless communications in a MIMO (multiple-input multiple-output) system, which is developed from combining the orthogonal frequency division multiplexing (OFDM) with the diagonal block orthogonal algebraic space-time block code (DBOASTBC) and belongs a kind of MIMO-OFDM multicarrier systems. The methods of encoding...
MIMO-OFDM is widely recognized today as a key combination of technologies to achieve high spectral efficiency and high link reliability over space and frequency selective wireless channels, at a reasonable hardware cost. Both OFDM and MIMO have a variety of modes of operation and parameters and for each channel state, users?? requirements of data transmission and criterion of estimation performance,...
Orthogonal frequency division multiplexing (OFDM) is the modulation scheme of choice for digital video broadcasting-handheld (DVB-H), which is required to operate under high mobility conditions resulting in significant Inter-carrier Interference (ICI). To mitigate ICI, several cancellation schemes have been proposed but they require reliable channel information at the receiver which is quite challenging...
Some communication applications, like multimedia, deliver data of different importance classes allowing unequal error protection (UEP) levels. In this paper, a multiple-input multiple-output (MIMO) system using orthogonal frequency division multiplexing (OFDM) is considered with a new UEP bit-loading algorithm based on the non-UEP algorithm by Chow, Cioffi, and Bingham. In the proposed bit-loading...
This paper proposes a new space-frequency (SF) code construction scheme that can fully exploit both spatial and frequency diversities while providing great coding advantage and maintaining high bandwidth efficiency for MIMO-OFDM system operating in frequency-selective channels. The proposed SF code construction method is based on a class of trellis codes, where the trellis branches are labeled with...
Effects of improved channel estimation are studied for a proposed IEEE 802.11n OFDM MIMO system. Three channel estimation methods are considered: maximum likelihood (ML), time-domain truncation (TDT) and model-based (MB). TDT and MB are particularly useful when the channel delay spread is short. For an MMSE receiver, MB shows a 1-2.5 dB improvement over ML on the packet error rate performance for...
In this paper, we consider a new channel probing scheme for opportunistic scheduling in the uplink of orthogonal frequency division multiplexing (OFDM)-based wireless systems. To reduce signaling overhead for the probing, we consider a two-step channel probing process; called pre-probing and mainprobing. Good subchannels are first estimated through the pre-probing process using a probing signal transmitted...
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