WARP Featured in Course Projects at SMU
The Embedded Wireless Design Laboratory at Southern Methodist University uses WARP to teach students fundamental concepts in wireless communications and networking. After learning the fundamentals, the course then asks students to design novel wireless protocols and characterize those designs with experiments as part of a final project. The Fall 2015 class produced the following outstanding projects built on WARP:
Distributed Beamforming Feasibility Testing
Authors: Krupal A. Desai, Nikhil T. Mali, Nupur R. Patel, Vivek K. Shah
Distributed beamforming is a communication technique in which multiple sources transmit the same message signal at the same time and the phase of the transmitted signal is controlled in a way that the signals have constructive interference at the receiver. This paper presents a review of related work focused on implementing distributed beamforming using various techniques, also it measures and compares the amplitude as well as RSSI (Receiver Signal Strength Indicator) of the received signal for three different cases at different points in the particular area (known as grid) with respect to the reference node. The three different cases are; without beamforming (SISO), with beamforming (MISO), and with distributed beamforming (MISO).
Nakagami Channel Emulation
Authors: Rita Enami, Mingchao Tan, Zhe Li
Different wireless devices form a notion of channel quality with averaging of the received signal power. Since the RSSI (Received Signal Strength Indicator) impacts the functionality of the mobile radio communication, it is meaningful to investigate the effect of the various calculation methods of this parameter in different devices. Among different methods for modeling the wireless channels, the stochastic method is the simple one with a low computational complexity, which uses the RSSI to model the channel propagation. Since Nakagami is a common and flexible way to model the fading of a wireless channel, we investigate the role of averaging RSSI on the accuracy of the distribution. This paper presents that how the averaging of the received signal strength influence the received signal distribution in WARP board transmission.
MIMO Adaptation between diversity-multiplexing based on Channel Estimates for varying modulation techniques, coding rates and transmission power
Authors: Rebecca Almeida, Peiqin Li, Qian Hu, Qingyao Pan
Wireless communication in today's world has become one of the most popular and utilized technologies. As the number of users keep on increasing, the demand for high-speed data is becoming more prominent. In order to fulfill this growing demand, many wireless technologies have opted for MIMO systems. It has become a priority to provide all these users with high-speed data-access having high reliability. For MIMO systems, high speed data-rates can be achieved using multiplexing scheme when the channel conditions are observed to be very good. For poor channel conditions, diversity scheme is shown to provide higher reliability. In most of the practical systems however, the channel conditions will vary between these two extremes. Also, the performance of these schemes will heavily depend upon various other parameters such as the transmission power used, the coding rates and modulation techniques applied on the user data, etc. Under these varying conditions, it becomes difficult to decide which of these two schemes will give best performance.
Multiband Channel Sounding based on the analysis of power delay profile for 2.4GHz and 5GHz
Authors: Yang Yu, Akshay Arora,Wang Yang, Ameya Shetye
This paper focuses on the comparison of power delay profiles for different environments like different room dimensions. Also for the exact same environment, we compare the multipath path properties across the IEEE 802.11 Wi-Fi spectrum for 2.4GHz and 5GHz channels. This project also shows the different multipath propagation parameters like RMS delay spread, maximum excess delay and mean excess delay that are derived from the power delay profile. Thus, this power delay profile testing method will help us understand the multipath effects on a multiband and also its study will help to estimate the causes of inter symbol interference on the channel for different environmental scenarios.
Full Duplex MAC Design
Authors: Yan Shi, Brendan Celii, and Dhruvang Darji
In this project, we have re-designed the full duplex (FD) medium access control (MAC) protocol based on IEEE 802.11 standard for Wireless Local Area Network System (WLAN) according to the hard requirement that no modification is allowed on the client’s protocol. We discuss about potential solutions to the problem of Multiple ACK collision using implicit multi-user MIMO technique and demonstrate the feasibility of our MAC protocol when implemented in various scenarios. Some extensional works have been proposed for the next project phase.
Channel Orthogonality Measurements in Multi-User Beam Forming
Authors: Hua Cai, Jesal Desai, Nikunj Radadia, Nick Saulnier
A wireless system with multiple transmitting and multiple receiving antennas is a multi-in, multi out (MIMO) system. In multi-user MIMO, a transmitter with multiple antennas communicates with multiple receivers at the same time, where the receivers may have one or more antennas. The problem of a single base station communicating with multiple receivers is typically addressed with time-division multiple access (TDMA). However, space-division multiple access (SDMA) can allow multiple users to be serviced simultaneously. This allows access points to service more users more efficiently by increasing the maximum channel capacity in crowded Wifi spectrums. Multi-user beamforming (MUBF) provides a powerful way to implement SDMA. We will generate beams using zero-forcing beamforming (ZFBF). ZFBF weights the signals sent from each transmit antenna to each receiver by generating a beamforming matrix. Currently, these weights must be constantly re-evaluated as receivers move relative to the transmitter or change frequency bands. Our work measures how the spatial orthogonality of two different beams varies (if at all) for a given set of weights at given receiver locations across multiple frequency bands occur, especially if those bands span multiple GHz. This will inform beamforming algorithms in the future – if beam orthogonality does not suffer when the same weights are reused for the same receiver locations at different frequency bands, then the transmitter’s computational load may be reduced.