MIMO and Beamforming for 4G Wireless with Applications to LTE and WiMax

Available as a corporate-exclusive / tailored course at your site.

TECHNOLOGY FOCUS 
Even as Third Generation (3G) cellular service is being deployed, the wireless community is busy designing the fourth generation (4G) of wireless cellular systems. While the definition of 4G has not been finalized, there is a consensus that the expected data rate requirements will be an order of magnitude higher than 3G. Current technologies based on TDMA/CDMA are not capable of handling the wideband signals required to reach the 4G target data rates. Two technologies working in tandem are emerging as likely candidates for 4G implementations. Orthogonal frequency division multiplexing (OFDM) has already proved successful in providing high speed communication over wireless LANs. OFDM greatly facilitates handling wideband signals, but, by itself, it cannot deliver the data rates targeted by 4G. Multiple input-multiple output (MIMO) is seen as the key technology to complement OFDM to support high data rates in future wireless systems. MIMO schemes enable a variety of functions including multi-stream transmission for high spectrum efficiency, improved link quality through diversity mechanisms, and adaptation of radiation patterns for signal gain and interference mitigation through adaptive beamforming. 

COURSE CONTENT AND OBJECTIVES 
This course covers MIMO communications on all its aspects. Simple examples designed to reinforce the concepts, supplement the material. 
Design principles and tradeoffs are discussed in detail. Matlab software is used to demonstrate key concepts. Participants may use the software for hands-on analysis and simulations, and work through review problems that reinforce key notions introduced in the section. Application examples include 3G and beyond 3G (B3G) cellular systems. The last day of the course presents in detail the application of MIMO to 3GPP LTE and WiMax. The course will prepare participants to:

• Understand the concepts of adaptive beamforming, i.e., the use of 
  antenna arrays to control radiation patterns over line of sight channels
• Grasp the phenomenology and theory that underlie the dramatic increases in data rates enabled by MIMO
• Become familiar with the fading characteristics of the wireless transmission 
  medium and the ability of diversity systems to mitigate fading effects
• Understand the concept of spatial multiplexing and the various schemes for its implementation
• Learn about major system applications of MIMO to 3G and 4G cellular communication systems
• Become familiar with the application of MIMO to single user and multiuser communication

Monday
MIMO Channels and MIMO Capacity 

We start with a quick review of communications over line of sight and fading channels. Antenna arrays are introduced. Beamforming and adaptive antenna pattern adaptation are presented. The properties of distributed arrays are discussed. From the line of sight channel, we move on to the fading channel. In this part, we introduce properties of the MIMO channel, and present standardized models. The discussion underscores the multipath MIMO channel as the enabler to the high spectral efficiency MIMO communications. Fundamental properties of MIMO communication are introduced and explained through the concept of channel capacity.

• Properties of Adaptive Arrays, Array Gain, Beampattern, Transmit and Receive Arrays
• Distributed Arrays
• MIMO Channel, Physical, Analytical, Deterministic, and Stochastic Models
• Standardized Models: COST, 3GPP, WINNER, IEEE 802.11n, SUI Models for WiMax
• MIMO Capacity, Channel Known at the Transmitter
• Capacity of Deterministic and Fading Channels

Tuesday
Receive and Transmit Diversity 
Diversity mechanisms are commonly applied to overcome fading over wireless channels. We discuss the use of antennas at the receiver and at the transmitter to the design of diversity systems. Space-time codes are introduced. The concepts of coding gain and diversity gain are shown to determine the performance of space-time codes. 
We discuss examples of space-time codes, their design, performance, and complexity, and their emergence in wireless cellular standards.

Diversity Concept: Time, frequency, and spatial diversity

Diversity with Receive Antennas: MRC, equal gain, selective, and optimum 
combining, correlated channels

Channel Estimation Error

Diversity with Transmit Antennas, Alamouti's Scheme, Space-time Block Codes

Transmit Diversity Schemes for 3GPP and 3GPP2

Phase Sweeping, Delay Diversity, Cyclic Delay Diversity

Wednesday
MIMO Systems, OFDM, and Multiuser MIMO 
In this part, we focus on the capability of MIMO systems to support the transmission of multiple streams of data. Specific schemes that implement spatial multiplexing are discussed. The effect of channel state information on the performance of MIMO systems is discussed. The availability of channel state information at the transmitter can support higher data rates, but requires a feedback mechanism from the receiver. We discuss the advantages of channel state information at the transmitter and the tradeoffs between feedback overhead and performance. We present the basics of OFDM technology, and discuss MIMO OFDM systems. Advanced concepts that optimize system performance with respect to multiple users are introduced.

• Spatial Mutliplexing Systems: BLAST, layered schemes
• Closed Loop Systems: Diversity systems, spatial multiplexing over eigenmodes
• MIMO Applications: Standardization in 3GPP and 3GPP2
• OFDM Basics, Cyclic Prefix, Rate Adaptation, Channel Equalization, OFDMA
• Multiuser Communication and Diversity
• Multiuser MIMO: Successive interference cancellation, superposition coding, and WiMax proposal

Thursday
UMTS LTE and WiMax Applications 
OFDM and MIMO will serve as the physical layer of two key technologies for future mobile communication systems: LTE and WiMax. LTE is the 4G evolution of cellular systems, while WiMax is a technology that is expected to deliver last mile wireless broadband access. Both 3GPP LTE and WiMax technologies make extensive use of MIMO. We will discuss requirements for the two systems, followed by a description of the physical layer, which is expected to be based on OFDMA. MIMO schemes under consideration for 3GPP LTE and already standardized for Mobile WiMax IEEE 802.16e will be described in detail.

• Background to LTE: HSPA Release 7
• LTE Design Goals
• LTE Downlink; MIMO Modes
• LTE Uplink; MIMO Modes
• MIMO OFDM for LTE
• WiMax Network Architecture
• OFDMA Pphysical Layer; Scalable OFDMA
• Adaptive Modulation and Coding
• OFDMA Channelization: PUSC, FUSC, AMC
• Multiple Antenna Technology in WiMax
• MAC layer, MAC Protocol Data Units
• Frame Structure
• Ranging
• Quality of Service Classification
• ARQ