Showing papers on "Spectral efficiency published in 2000"

Increase in capacity of multiuser OFDM system using dynamic subchannel allocation

Abstract: This paper investigates the problem of dynamic multiuser subchannel allocation in the downlink of OFDM systems. The assumptions are that the channel model is quasi-static and that the base station has perfect channel information. In traditional TDMA or FDMA systems, resource allocation for each user is non-adaptively fixed, and the water-filling power spectrum is known to be optimal. Since the subchannel allocations among the users are not optimized, a group of users is likely to suffer from poor channel gains resulting from large path loss and random fading. To resolve this problem, we derive a multiuser convex optimization problem to find the optimal allocation of subchannels, and propose a low-complexity adaptive subchannel allocation algorithm. Simulation results show that the proposed algorithm performs almost as well as the optimal solution. Also, a higher spectral efficiency is achieved for a larger number of users in a cell due to the multiuser diversity.

Adaptive Modulation over Nakagami Fading Channels

Abstract: We first study the capacity of Nakagami multipath fading (NMF) channels with an average power constraint for three power and rate adaptation policies. We obtain closed-form solutions for NMF channel capacity for each power and rate adaptation strategy. Results show that rate adaptation is the key to increasing link spectral efficiency. We then analyze the performance of practical constant-power variable-rate M-QAM schemes over NMF channels. We obtain closed-form expressions for the outage probability, spectral efficiency and average bit-error-rate (BER) assuming perfect channel estimation and negligible time delay between channel estimation and signal set adaptation. We also analyze the impact of time delay on the BER of adaptive M-QAM.

Increasing data rate over wireless channels

Abstract: Space-time coding (STC) is a new coding/signal processing framework for wireless communication systems with multiple transmit and multiple receive antennas. This new framework has the potential of dramatically improve the capacity and data rates. In addition, this framework presents the best trade-off between spectral efficiency and power consumption. ST codes (designed so far) come in two different types. ST trellis codes offer the maximum possible diversity gain and a coding gain without any sacrifice in the transmission bandwidth. The decoding of these codes, however, would require the use of a vector form of the Viterbi decoder. Space-time block codes (STBCs) offer a much simpler may of obtaining transmit diversity without any sacrifice in bandwidth and without requiring huge decoding complexity. In fact, the structure of the STBCs is such that it allows for very simple signal processing (linear combining) for encoding/decoding, differential encoding/detection, and interference cancellation. This new signal processing framework offered by ST codes can be used to enhance the data rate and/or capacity in various wireless applications. That is the reason many of these STC ideas have already found their way to some of the current third-generation wireless systems standards.

Improved codes for space-time trellis-coded modulation

Abstract: Space-time coded modulation has been shown to efficiently use transmit diversity to increase spectral efficiency. We propose new trellis codes found through systematic code search. These codes achieve the theoretically maximal diversity gain and improved coding gain compared to known codes.

Adaptation techniques in wireless packet data services

Abstract: Today's cellular systems are designed to achieve 90-95 percent coverage for voice users (i.e., the ratio of signal to interference plus noise must be above a design target over 90 to 95 percent of the cell area). This ensures that the desired data rate which achieves good voice quality can be provided "everywhere". As a result, SINRs that are much larger than the target are achieved over a large portion of the cellular coverage area. For a packet data service, the larger SINR can be used to provide higher data rates by reducing coding or spreading and/or increasing the constellation density. It is straight-forward to see that cellular spectral efficiency (in terms of b/s/Hz/sector) can be increased by a factor of two or more if users with better links are served at higher data rates. Procedures that exploit this are already in place for all the major cellular standards in the world. In this article, we describe data rate adaptation procedures for CDMA (IS-95), wideband CDMA (cdma2000 and UMTS WCDMA), TDMA (IS-136), and GSM (GPRS and EDGE).

Beyond 3G: wideband wireless data access based on OFDM and dynamic packet assignment

Abstract: The rapid growth of wireless voice subscribers, the growth of the Internet, and the increasing use of portable computing devices suggest that wireless Internet access will rise rapidly over the next few years. Rapid progress in digital and RF technology is making possible highly compact and integrated terminal devices, and the introduction of sophisticated wireless data software is making wireless Internet access more user-friendly and providing more value. Transmission rates are currently only about 10 kb/s for large cell systems. Third-generation wireless access such as WCDMA and the evolution of second-generation systems such as TDMA IS-136+, EDGE, and CDMA IS-95 will provide nominal bit rates of 50-384 kb/s in macrocellular systems. This article discusses packet data transmission rates of 2-5 Mb/s in macrocellular environments and up to 10 Mb/s in microcellular and indoor environments as a complementary service to evolving second- and third-generation wireless systems. Dynamic packet assignment for high-efficiency resource management and packet admission; OFDM at the physical layer with interference suppression, space-time coding, and frequency diversity; as well as smart antennas to obtain good power and spectral efficiency are discussed in this proposal. Flexible allocation of both large and small resources also permits provisioning of services for different delay and throughput requirements.

Dynamic assignment of orthogonal variable-spreading-factor codes in W-CDMA

Abstract: This paper presents an optimal dynamic code assignment (DCA) scheme using orthogonal variable-spreading-factor (OVSF) codes. The objective of dynamic code assignment is to enhance statistical multiplexing and spectral efficiency of W-CDMA systems supporting variable user data rates. Our scheme is optimal in the sense that it minimizes the number of OVSF codes that must be reassigned to support a new call. By admitting calls that would normally be blocked without code reassignments, the spectral efficiency of the system is also maximized. Simulation results are presented to show the performance gain of dynamic code assignment compared to a static assignment scheme in terms of call blocking rate and spectral efficiency. We also discuss various signaling techniques of implementing our proposed DCA scheme in third-generation wideband CDMA systems.

Adaptive multidimensional coded modulation over flat fading channels

Abstract: We introduce a general adaptive coding scheme for Nakagami multipath fading channels. An instance of the coding scheme utilizes a set of 2L-dimensional (2L-D) trellis codes originally designed for additive white Gaussian noise (AWGN) channels. Any set of 2L-D trellis codes for AWGN channels can be used, Sets for which all codes can be generated by the same encoder and decoded by the same decoder are of particular interest. A feedback channel between the transmitter and receiver makes it possible to transmit at high spectral efficiencies under favorable channel conditions and respond to channel degradation through a smooth reduction of the spectral efficiency. We develop a general technique to determine the average spectral efficiency of the coding scheme for any set of 2L-D trellis codes. As an illustrative example, we calculate the average spectral efficiency of an adaptive codec utilizing eight 4-D trellis codes. The example codec is based on the International Telecommunications Union's ITU-T V.34 modem standard.

A combined OFDM/SDMA approach

Abstract: Two major technical challenges in the design of future broadband wireless networks are the impairments of the propagation channel and the need for spectral efficiency. To mitigate the channel impairments, orthogonal frequency division multiplexing (OFDM) can be used, which transforms a frequency-selective channel in a set of frequency-flat channels. On the other hand, to achieve higher spectral efficiency, space division multiple access (SDMA) can be used, which reuses bandwidth by multiplexing signals based on their spatial signature. In this paper, we present a combined OFDM/SDMA approach that couples the capabilities of the two techniques to tackle both challenges at once. We propose four algorithms, ranging from a low-complexity linear minimum mean squared error (MMSE) solution to the optimal maximum likelihood (ML) detector. By applying per-carrier successive interference cancellation (pcSIC), initially proposed for DS-CDMA, and introducing selective state insertion (SI), we achieve a good tradeoff between performance and complexity. A case study demonstrates that, compared to the MMSE approach, our pcSIC-SI-OFDM/SDMA algorithm obtains a performance gain of 10 dB for a BER of 10/sup -3/, while it is only three times more complex. On the other hand, it is two orders of magnitude less complex than the ML approach, for a performance penalty of only 2 dB.

On the white Gaussian multiple-access relay channel

Abstract: The spectral efficiency of mobile radio networks can be improved by allowing each mobile station to act as a relay for one other mobile station. One can expect further performance improvement if each relay aids not just a single mobile station, but many simultaneously. We attempt to quantify this improvement by introducing the multiple-access relay channel (MARC) and deriving capacity results for it. Capacity outer and inner bounds for it are derived.

Space division multiplexing (SDM) for OFDM systems

Abstract: A promising solution for significant increase of the bandwidth efficiency and transmission capacity is the exploitation of the spatial dimension, by using space division multiplexing (SDM). SDM algorithms exploit the richly scattered (indoor) wireless channel by using multiple transmit and receive antennas. A new SDM technique, called maximum likelihood decoding (MLD) is proposed. The superior SNR performance of MLD compared to other SDM techniques is proven. To obtain an even higher bit rate and make the system more robust against intersymbol interference, (single-carrier) SDM is successfully applied to the spectrum efficient multi-carrier transmission technique orthogonal frequency division multiplexing (OFDM).

Turbo code symbol interleaver

Abstract: Advantageous error rate performance, high bandwidth efficiency, low delay and reduced error floor are achieved at an acceptable level of decoding complexity via the use of serial concatenated turbo codes. These are codes for which at least some of the output bits, including at least one redundant bit, provided by a first, outer encoder are, after interleaving, further processed by a second, inner encoder. The interleaver uses as its interleaved elements the bits associated with a particular symbol interval. The resulting data and redundant bits then select a symbol from a predetermined constellation for transmission. In the receiver, the turbo code is decoded using a corresponding number of soft output decoders which operates iteratively in such a way that improved performance as compared to a single encoding can be achieved. The turbo codes can be of various dimensionalities and can be used as a component of a multilevel code to achieve a desired level of bandwidth efficiency.

Turbo code termination

Abstract: Advantageous error rate performance, high bandwidth efficiency, low delay and reduced error floor are achieved at an acceptable level of decoding complexity via the use of serial concatenated turbo codes. These are codes for which at least some of the output bits, including at least one redundant bit, provided by a first, outer encoder are, after interleaving, further processed by a second, inner encoder. The resulting data and redundant bits then select a symbol from a predetermined constellation for transmission. In the receiver, the turbo code is decoded using a corresponding number of soft output decoders which operates iteratively in such a way that improved performance as compared to a single encoding can be achieved. The turbo codes can be of various dimensionalities and can be used as a component of a multilevel code to achieve a desired level of bandwidth efficiency. The turbo codes may be terminated such that after random input data has been applied to the turbo encoder for some number of symbol intervals, data other than random input bits is thereupon applied to the turbo encoder over a sufficient number of symbol intervals so as to bring each of the encoders to a known state.

Analysis of the uplink of an asynchronous multi-user DMT OFDMA system impaired by time offsets, frequency offsets, and multi-path fading

Abstract: We study through analysis the joint effect of time offsets, frequency offsets, and multi-path fading in the uplink of an asynchronous multi-user system for wireless communications deploying discrete multi-tone modulation and demodulation. We derive analytical expressions for the multiple access interference, and we quantify its detrimental effects through the evaluation of both the average SINR, and the symbol-error-rate performance. As a result it is shown that the MAI strongly depends not only on the aforementioned impairments but also on the tone assignment algorithm used to multiplex the users. Based on our analysis, the insertion of appropriate time and frequency guard intervals and the accurate selection of the tone assignment algorithm effectively reduce the MAI, so that a proper trade off with spectral efficiency can be met to optimize system performance.

Channel estimation and equalization for M-QAM transmission with a hidden pilot sequence

Abstract: Blind equalization techniques are useful to counteract multipath effects in radio local loop (RLL) and in general for wireless point to multipoint transmissions. One of the main drawbacks of blind equalization is the slow convergence time of the equalizer. Another major problem of blind equalization is the possible convergence toward wrong solutions. When these two main disadvantages cannot be tolerated it is necessary to adopt trained channel estimation and/or equalization techniques to counteract multipath. The training sequence is usually time division multiplexed with the informative sequence. This solution reduces the bandwidth efficiency and can be unusable when too frequent updating of the communications parameters need to be performed in the receiver. It is shown that bandwidth efficiency can be preserved at the expense of an increase in the transmitted power. The additional transmitted power is used to send a known pilot sequence hidden into the informative sequence. The hidden sequence is superimposed onto the symbols to be transmitted before waveform modulation. Thus each pilot symbol has the same period of the informative symbol so that no bandwidth spreading is necessary. High spectral efficiency M-QAM modulation is considered but the technique can be easily extended to any type of digital modulation format. We analyze the problems of channel estimation and of equalization based on the hidden pilot sequence. To prove the effectiveness of the proposed technique simulation results are provided. It is observed that in the case of equalization a pilot recovery subsystem should be used before using the pilot to train the equalizer.

Space-time coding and channel estimation scheme, arrangement and method

Abstract: The evolution of high rate data services within future wireless networks will call for new RF access technologies to enable substantial increases in overall system spectral efficiency at an acceptably low cost to the user. Space-Time Coding (STC) is an antenna array processing technology currently simulating considerable Interest across the wireless industry. The invention provides a space-time coding apparatus having an input, a trellis encoder, a modulator, a demultiplexer, and a set of signal outputs wherein the input is operable to receive a stream of data. This allows de-multiplexing to take place after coding and modulation has been performed. The trellis encoder comprises a convolutional encoder operable to sequentially group data to provide coded bits to provide QPSK symbols. By the selection of convolutional encoder rates and/or modulation alphabets STCs of any desired dimensionality may be produced including multi-dimensional codes.

Reduced-complexity detection algorithms for systems using multi-element arrays

Abstract: In BLAST (Bell-Laboratories LAyered Space Time) systems, multiple transmit and receive antennas are employed to achieve very high spectral efficiencies. The ideal detection method for such systems is the maximum-likelihood (ML) algorithm. However, the ML complexity increases exponentially with the number of transmit antennas and the number of bits per modulation symbol. A reduced-complexity detection method has been suggested, using ordered successive interference cancellation. We consider two other suboptimum techniques: channel-based adaptive group detection and multistep reduced-constellation detection. The goal is to reduce the two aforementioned complexity exponentials. The algorithms efficiently combine linear processing with local ML search. We limit the complexity by maintaining small ML searching areas, while maximizing the performance under the complexity constraint by optimizing the front-end linear processing and the selection of the search areas.

Energy-efficient TDMA medium access control protocol scheduling

Abstract: In this paper we study the energy efficiency and channel efficiency of TDMA MAC protocol scheduling mechanisms. Most MAC protocols are based on phase grouping that basically has three phases in a frame: uplink, downlink and reservation. We propose a new mechanism in which we have multiple uplink and downlink phases. These phases are grouped per mobile in a frame. Although this has a negative effect on the capacity of the channel, it allows the mobile to turn the power off from the wireless interface for a longer period. We made this choice since in a mobile multimedia environment it is more important that connections have a certain QoS, than highest possible bandwidth. We present an analysis in which these two basic mechanisms are compared in respect to bandwidth efficiency and energy efficiency. We have developed and implemented a novel MAC protocol based on mobile grouping that provides Quality of Service (QoS) support for diverse traffic types.

Strategies for realizing optical CDMA for dense, high-speed, long span, optical network applications

Abstract: Since the mid 1990s, the role of optical CDMA has expanded from local area networks to longer span, telecommunication-type networks. In order to play a significant role in these longer span, denser, higher data rate networks, optical CDMA code set must (1) have at least as many codes as dense wavelength division multiplexing (WDM) (i.e., more than eight codes); (2) operate at high data rates (i.e., greater than 2.5 Gb/s); and (3) propagate with high fidelity over the installed or installable fiber links. Most approaches to optical CDMA require narrow pulses, which are more susceptible to fiber impairments and may have lower spectral efficiency than conventional WDM modulation schemes such as non-return-to-zero (NRZ), so they do not meet these new requirements. Therefore, we have formulated a strategy which simultaneously increases the number of good codes (resulting in higher density) and reduces their code length (i.e., decreasing the number of time slots required thus enabling higher data rates for a given chip time): the strategy of matrix codes. In this paper, we describe the design of a set of eight matrix codes for operation at 2.5 Gb/s and evaluate their propagation over an existing 214 km network link by means of computer simulation. The results indicate that the codes propagate well if dispersion management is used. The paper also discusses a strategy for managing the multiaccess interference (MAI) in a bursty traffic environment.

Space division multiplexing algorithms

Abstract: The main goals in developing new wireless communication systems are increasing the transmission capacity and improving the spectrum efficiency. In this paper, spectrum efficiency and capacity improving techniques, captured under the name space division multiplexing (SDM), are proposed. SDM algorithms exploit the richly scattered (indoor) wireless channel by transmitting different signals simultaneously on different transmit antennas at the same frequency and using multiple receive antennas for decoding. Among these algorithms, maximum likelihood decoding (MLD) is shown to have the best SNR performance.

Downlink and uplink channel structures for downlink shared channel system

Abstract: An uplink and downlink channel structure supports a shared downlink data channel. The new structure accommodates advanced physical and Medium Access Control (MAC) layer techniques, such as incremental redundancy (IR), fast adaptation to channel conditions, and multiple input multiple output (MIMO) antenna configuration. The proposed changes are intended to lead to a downlink structure that achieves higher spectral efficiency for the packet oriented services over then shared downlink channel. Additionally, the new structure uses the base station transmit power information and of the channelization (OVSF) code space more efficiently.

Smart antennas for combined DOA and joint channel estimation in time-slotted CDMA mobile radio systems with joint detection

Abstract: In cellular mobile radio systems, the directional inhomogeneity of the mobile radio channel can be exploited by smart antennas to increase the spectral efficiency. In this paper, a novel smart antenna concept applying receiver antenna diversity at the uplink receiver is investigated for a time-slotted code-division multiple-access (CDMA) mobile radio air interface termed time-division CDMA (TD-CDMA), which has been selected by the European Telecommunications Standards Institute (ETSI) in January 1998 to form part of the Universal Mobile Telecommunications System (UMTS) air interface standard. First, a combined direction-of-arrival (DOA) and joint channel estimation scheme is presented, which is based on DOA estimation using the Unitary ESPRIT algorithm and maximum likelihood estimation of the channel impulse responses associated with the estimated DOA's, which can also be used as an input for advanced mobile positioning schemes in UMTS. The performance of the combined DOA and joint channel estimation is compared with the conventional channel estimation through simulations in rural and urban propagation environments. Moreover, a novel joint data detection scheme is considered, which explicitly takes into account the signal DOA's and the associated channel impulse responses. The link level performance of a TD-CDMA mobile radio system using these novel schemes is evaluated by Monte Carlo simulations of data transmission, and average bit error rates (BER's) are determined for rural and urban propagation environments. The simulation results indicate that, depending on the propagation environment, the exploitation of the knowledge of the directional inhomogeneity of the mobile radio channel can lead to considerable system performance enhancements.

Throughput maximization in CDMA uplinks using adaptive spreading and power control

Abstract: We formulate the throughput maximization problem for CDMA uplinks as an optimization problem in terms of the spreading gains (equivalently transmission bit rates) and transmit powers of the users, and solve it using a nonlinear programming approach. In nearly all cases, the solution is to give a rate of W to the highest-path-gain user in each cell and virtually nothing to the others. This approach maximizes total throughput at the expense of fairness. We then extend the notion of one-user-at-a-time by assuming all users get served on a time-sharing basis. The result is a considerable gain in fairness, with a modest loss in total throughput. The average user throughput (per timeslot) now ranges from W near the base to /spl sim/0.4 W near the cell boundaries, and the average cell throughput drops by 33%. Also, compared to rate-control-only (no power control), we show that optional power allocation considerably improves both average cell throughput and transmit power usage at the terminals.

Experimental investigation of multipath richness for multi-element transmit and receive antenna arrays

Abstract: The multi-element antenna arrays concept with M elements at the mobile station (MS) in combination with N elements at the base station (BS) is experimentally investigated. Forschini (1996) has shown very promising results to improve the spectral efficiency in a rich scattering environment. The performance of the M/spl times/N concept is evaluated in terms of the number of independent parallel channels, diversity gain and total capacity in an outdoor to indoor microcellular environment. It is shown that the eigenanalysis provides a tool to describe the effective number of parallel channels in a multi-element array configuration. Practical results on spectral efficiency are presented for different antenna setups applied to different propagation scenarios. Also it is shown that polarization diversity is an attractive solution to achieve decorrelated antenna elements and subsequently provide a more robust system in terms of spectral efficiency within the microcell. Results show that a total capacity of 27.9 b/s/Hz can be achieved for an uncorrelated propagation environment and 17 b/s/Hz for a correlated one with a mean signal to noise ratio (SNR) of 30 dB in the case of a 4/spl times/4 antenna set-up.

Spectral efficiency of wireless systems with multiple transmit and receive antennas

Abstract: Recent information-theory results have shown the enormous capacity potential of wireless techniques that use transmit and receive antenna arrays. As a result, a number of layered space-time (BLAST) architectures have been proposed wherein multiple data streams are transmitted in parallel and separated at the receiver on account of their distinct spatial signatures. While extremely promising, all analysis of BLAST to date were restricted to the context of a single-user link. In this paper, the system-level benefit of using BLAST in multicell scenarios is evaluated in comparison with other directive- and adaptive-array techniques.

Recursive space-time trellis codes for turbo coded modulation

Abstract: Space-time coding schemes are focused on merging antenna diversity with appropriate channel coding in order to exploit benefits of spatial and temporal diversity. We propose the concept of recursive space-time trellis codes for parallel-concatenated space-time turbo coded modulation. The newly proposed scheme was designed to preserve the maximum transmit diversity gain but simultaneously enhance the coding gain as compared to Tarokh et al. (see IEEE Trans. Inf. Th., vol.44, no.2, 1998) space-time trellis codes. Puncturing the outputs of component codes enabled a considerable improvement in power efficiency to be obtained with no cost in bandwidth efficiency. A good performance was reported already with extremely short input information frames of 130 bits.

Method and apparatus for high data rate wireless communications over wavefield spaces

Abstract: The invention relates to a method and apparatus for digital communications that provides high data rate wireless connections with bandwidth efficiency. The creation of multiple channels (that share the same time-frequency region) between the transmitter and the receiver is achieved by sampling the wavefield space with respect to the spatial domain. The wavefield space is the space spanned by the channel parameters that characterize the multipath fading environment. At the transmitter, symbols are simultaneously modulated and transmitted using signals that occupy the same frequency portion of the spectrum, but are distinguishable because different is their position in the wavefield space. The received signals are optimally processed to extract the digital information. The optimum demodulator estimates the wavefield space parameters without any training sequence or signal and performs optimum separation of the different signals to obtain the multiple streams. The throughput of such communication system is an integer multiple of the throughput that is achievable at each different position in the wavefield space. Given a perfect estimate of the wavefield space parameters, the Maximum Likelihood principle is the optimum strategy for detection. When the wavefield space parameters are a-priori unknown, the Maximum Likelihood detector can not be implemented. The invention describes the use of a focused wavelet-based model in the statistic of the detector which results in an effective approach to wavefield space demodulation without training signals or sequences in frequency selective multipath fading with arbitrarily time-varying fading characteristics.

W-CDMA capacity and planning issues

Abstract: Third generation (3G) mobile networks are due to become reality in the next few years as governments world-wide start to auction or 'release' new spectrum to new and existing cellular operators. A major differentiation of 3G over second generation networks is the provision of multiple-data-rate services, higher spectrum efficiency and greater flexibility of the air interface. This paper addresses FDD W-CDMA planning and capacity estimation issues. As well as addressing the planning steps, link budgets and simplistic uplink capacity estimation the paper goes into more detail on simulation methods and considerations. Finally an example W-CDMA network, based on realistic site locations in central London, is provided. Capacity estimations are given with some indications of network stability and operating points.

Link-optimal BLAST processing with multiple-access interference

Abstract: Previous results in information theory have demonstrated the enormous capacity potential of wireless communication systems with multiple transmit and receive antennas To exploit this potential, the Bell-laboratories LAyered Space-Time (BLAST) architecture was proposed BLAST systems transmit parallel data streams, simultaneously and on the same frequency, in a multiple-input multiple-output fashion With sufficient multipath propagation, these different streams can be separated at the receiver The link performance of BLAST has been thoroughly studied, but always in the presence of the spatially white noise However, in the context of a multiple-access system, the dominant impairment is usually co-channel interference that is-in general-spatially colored We present a generalization of BLAST that is optimal, in the sense of maximizing the link spectral efficiency, in the presence of spatially colored interference In this general scheme, the channel and interference covariance are made available to the transmitter, which finds the channel eigenmodes in the presence of the interference and sends multiple data streams through those eigenmodes We evaluate the spectral efficiency of this new architecture and compare it, under various propagation conditions, to other forms of BLAST in order to quantify the value of providing interference information to the transmitter Furthermore, the new scheme is also compared to other adaptive-array techniques with equal number of antennas

Mode lookup tables for data transmission in wireless communication channels based on statistical parameters

Abstract: A method and medium tangibly embodying the method of constructing a lookup table of modes for encoding data for transmission in a wireless communication channel from a transmit unit to a receive unit by using at least one quality parameter of the data and its first-order and second-order statistical parameters to arrange the modes in the lookup table. The first-order and second-order statistical parameters can be determined from a simulation of the wireless communication channel or from field measurements of the wireless communication channel. The modes in the lookup table are ordered by a target value of a communication parameter such as PER, BER, data capacity, signal quality, spectral efficiency, throughput or another suitable communication parameter set to achieve a desired quality of service. The quality parameter selected is conveniently a short-term quality parameter such as signal-to-interference and noise ratio (SINR), signal-to-noise ratio (SNR) or power level. During use adjustments depending on the instantaneous condition of the channel can be used to tune the lookup table.