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|Title:||Unitary Trace-Orthogonal Space-Time Block Codes in Multiple Antenna Wireless Communications|
|Advisor:||Reilly, James P.|
|Department:||Electrical and Computer Engineering|
|Keywords:||multiple-input, multiple-output (MIMO), communication system, space-time block codes (STBC), orthogonality property, unitary|
|Abstract:||<p> A multiple-input multiple-output (MIMO) communication system has the potential to provide reliable transmissions at high data rates. However, the computational cost of achieving this promising performance can be quite substantial. With an emphasis on practical implementations, the MIMO systems employing the low cost linear receivers are studied in this thesis. The optimum space-time block codes (STBC) that enable a linear receiver to achieve its best possible performance are proposed for various MIMO systems. These codes satisfy an intra and inter orthogonality property, and are called unitary trace-orthogonal codes. In addition, several novel transmission schemes are specially designed for linear receivers with the use of the proposed code structure. The applications of the unitary trace-orthogonal code are not restricted to systems employing linear receivers. The proposed code structure can be also applied to the systems employing other types of receivers where several originally intractable code design problems are successfully solved.</p> <p>The communication schemes presented in this thesis are outlined as follows: •For a MIMO system with N ≥ M, where M and N are the number of transmitter and receiver antennas, respectively, the optimal full rate linear STBC for linear receivers is proposed and named unitary trace-orthogonal code. The proposed code structure is proved to be necessary and sufficient to achieve the minimum detection error probability for the system. • When applied to a multiple input single output (MISO) communication system, a special linear unitary trace-orthogonal code, named the Toeplitz STBC, is proposed. The code enables a linear receiver to provide full diversity and to achieve the optimal tradeoff between the detection error and the data transmission rate. This is, thus far, the first code that possesses such properties for an arbitrary MISO system that employs a linear receiver. • In MIMO systems in which N ≥ M and the signals are transmitted at full symbol rate, the highest diversity gain achievable by linear receivers is analyzed and shown to be N - M + 1. To improve the performance of a linear receiver, a multi-block transmission scheme is proposed, in which signals are coded so that they span multiple independent channel realizations. An optimal full rate linear STBC for this system that minimizes the detection error probability is presented. The code is named multi-block unitary trace-orthogonal code. The resulting system has an improved diversity gain. Furthermore, by relaxing the code from the full symbol rate constraint, a special multi-block transmission scheme is proposed. This scheme achieves a much improved diversity gain than those with full symbol rate. • The unitary trace-orthogonal code can also be applied to a system that employs a maximum-likelihood (ML) receiver rather than the simple linear receiver. For such a system, a systematic design of full diversity unitary trace-orthogonal code is presented for an arbitrary data transmission rate. </p> <p>In summary, when a simple linear receiver is employed, unitary trace-orthogonal codes and their optimality properties are exploited for various multiple antenna communication systems. Some members from this code family can also enable an optimal performance of ML detection. </P>|
|Appears in Collections:||Open Access Dissertations and Theses|
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