Abstract — This paper presents Space Division Multiplexing (SDM) as a technology to satisfy the user demand for ever higher bit rates in wireless Local area network technology. SDM uses multiple transmit and receive antennas to increase bit rate proportionally, without reducing range, delay spread tolerance and spectrum occupancy. The optimal SDM receiver is the maximum likelihood decoder, whic...

The ‘fit’ of a garment is often considered to be a subjective measure of garment quality. However, some experts attest that a complaint of poor garment fit is a symptom of inadequate or excessive ease, the space between the garment and the wearer. Fit has traditionally been hard to quantify, and space suits are an extreme example, where fit is difficult to measure but crucial for safety and ope...

In this section we will give an overview of the paper; precise definitions of the terms used here will be found in Sections 2, 3 and 4. Our starting point is that there are several intriguing links between group theory and formal language theory. One of the many interesting such connections is the consideration of which groups G have a word problem lying in a particular class F of formal langua...

A new modulation method for linear space-time codes is proposed based on using constellations of different sizes for different symbols. The proposed method significantly reduces the complexity of the sphere decoding algorithm.

In this note, we show that while almost all functions require exponential size branching programs to compute, for all functions f there is a branching program computing a large number of copies of f which has linear size per copy of f . We then discuss which nonmonotone lower bound approaches for branching programs are ruled out by this result. Acknowledgement: This work was supported by the Si...

We exhibit a new method for showing lower bounds for time-space tradeoffs of polynomial evaluation procedures given by straight-line programs. From the tradeoff results obtained by this method we deduce lower space bounds for polynomial evaluation procedures running in optimal nonscalar time. Time, denoted by L, is measured in terms of nonscalar arithmetic operations and space, denoted by S, is...

Defining a feasible notion of space over the Blum-Shub-Smale (BSS) model of algebraic computation is a long standing open problem. In an attempt to define a right notion of space complexity for the BSS model, Naurois [CiE, 2007] introduced the notion of weak-space. We investigate the weak-space bounded computations and their plausible relationship with the classical space bounded computations. ...

| A design framework for space-time multiuser detectors is introduced based on the recently introduced notion of canonical space-time coordinates (CSTC). The CSTC system employs a xed set of basis signals which eliminates the need for estimating direction of arrivals (DOAs) and delays of the channel, thereby allowing signiicant reduction in receiver complexity. The proposed framework is based o...

The notion of online space complexity, introduced by Karp in 1967, quantifies the amount of space required to solve a given problem using an online algorithm, represented by a Turing machine which scans the input exactly once from left to right. In this paper, we study alternating algorithms as introduced by Chandra, Kozen and Stockmeyer in 1976. We devise a lower bound technique relying on bou...