Pilot Contamination Problem in Multi-Cell TDD Systems (2009)
Jose, Jubin, Ashikhmin, Alexei, Marzetta, Thomas L., Vishwanath, Sriram
This paper considers a multi-cell multiple antenna system with precoding used at the base stations for downlink transmission. To enable precoding, channel state information (CSI) at the base stations...
Scheduling and Precoding in Multi-User Multiple Antenna Time Division Duplex Systems (2008)
Jose, Jubin, Ashikhmin, Alexei, Whiting, Phil, Vishwanath, Sriram
The downlink transmission in multi-user multiple antenna wireless communication systems is generally studied assuming channel state knowledge and the topic of determining this channel knowledge is...
Estimates of the distance distribution of codes and designs (2008)
Alexei Ashikhmin, Er Barg, Simon Litsyn, Senior Member, Senior Member
Abstract—We consider the problem of bounding the distance distribution for unrestricted block codes with known distance and/or dual distance. Applying the polynomial method, we provide a general...
Linear codes with exponentially many light (2008)
Alexei Ashikhmin, Alexander Barg, Serge Vladut, G. Kalai
vectors
Linear codes with exponentially many light (2007)
Alexei Ashikhmin, Alexander Barg, Serge Vladut
vectors
Scheduling and Pre-Conditioning in Multi-User MIMO TDD Systems (2007)
Jose, Jubin, Ashikhmin, Alexei, Whiting, Phil, Vishwanath, Sriram
The downlink transmission in multi-user multiple-input multiple-output (MIMO) systems has been extensively studied from both communication-theoretic and information-theoretic perspectives. Most of...
Decoding of Expander Codes at Rates Close to Capacity (2005)
Ashikhmin, Alexei, Skachek, Vitaly
The decoding error probability of codes is studied as a function of their block length. It is shown that the existence of codes with a polynomially small decoding error probability implies the...
Extremal problems of information combining (2005)
Yibo Jiang, Alexei Ashikhmin, Ralf Koetter, Andrew C. Singer
Abstract — In this paper we study moments of soft-bits of binary-input symmetric-output channels and solve some extremal problems of the moments. We use these results to solve the extremal...
Nonbinary Quantum Stabilizer Codes (2000)
Ashikhmin, Alexei, Knill, Emanuel
We define and show how to construct nonbinary quantum stabilizer codes. Our approach is based on nonbinary error bases. It generalizes the relationship between selforthogonal codes over $GF_{4}$ and...
Quantum Error Detection I: Statement of the Problem (1999)
Ashikhmin, Alexei, Barg, Alexander, Knill, Emanuel, Litsyn, Simon
I. This paper is devoted to the problem of error detection with quantum codes. In the first part we examine possible problem settings for quantum error detection. Our goal is to derive a functional...
Improved estimates on covering radius (1999)
Ashikhmin, Alexei, Honkala, Iiro, Laihonen, Tero, Litsyn, Simon
On relations between covering radius and dual distance (1999)
Ashikhmin, Alexei, Honkala, Iiro, Laihonen, Tero, Litsyn, Simon
Upper Bounds on the Size of Quantum Codes (1997)
Ashikhmin, Alexei, Litsyn, Simon
Several upper bounds on the size of quantum codes are derived using the linear programming approach. These bounds are strengthened for the linear quantum codes.
Remarks on Bounds for Quantum Codes (1997)
We present some results that show that bounds from classical coding theory still work in many cases of quantum coding theory.
Minimal Vectors in Linear Codes and Sharing of Secrets (1994)
Alexei Ashikhmin, Alexander Barg
this paper were presented in part at the Fourth International Workshop "Algebraic and Combinatorial Coding Theory" (ACCT-4), Novgorod, 11--17 September 1994.