Interference multiple access wireless network demonstration enabled by real-time multiuser detection
ABSTRACT In recent outdoor, over-the-air tests and simulations, DARPA demonstrated greater than 3X improvement in aggregate wireless network throughput and latency compared to the 802.11b wireless local area network. This achievement is based on allowing multiple users to simultaneously use the same channel (time, frequency, code, etc.) without requiring a centralized infrastructure for coordination and spectrum preplanning. DARPA has developed new multi-user detection (MUD) algorithms that make it possible to exploit multi-access interference to increase network capacity. A key program goal is to apply these algorithms to next-generation warfighter communications systems for substantial capacity, latency and scalability improvements.
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- "To allow interference to support the MUD gains, a custom Media Access Control layer was developed . Each transmitter sends an asynchronous 8 chips/bit, QPSK signal to the receiver . The maximum power spread between the minimum and maximum powered users is limited to 40 dB. "
Conference Paper: Application of multiuser detection to the common data link waveform[Show abstract] [Hide abstract]
ABSTRACT: The growing use of small form factor unmanned aerial systems (UAS) in theater presents severe co-channel interference issues with todaypsilas radio technology. This paper addresses this concern by describing multiuser detection receiver technology and its application to the Common Data Link (CDL) ISR waveform protocol. By equipping CDL radios with MUD receiver technology developed under the DARPA Interference Multiple Access Communications Program, we show a significant reduction in spectrum pre planning requirements and increases in spectral efficiency. This technique enables multiple UASs to occupy the same channel at the same time without centralized coordination or power control.Military Communications Conference, 2008. MILCOM 2008. IEEE; 12/2008
- "Tests consisted of six radio nodes, as described in Figure 1 and depicted in Figure 6. Each node acted as a transceiver and carried out the DIMA protocol as described in Eisenberg . Ethernet connected the nodes to a test terminal to allow for remote configuration and control of the network. "
Conference Paper: Real time implementation of a multiuser detection enabled ad-hoc network[Show abstract] [Hide abstract]
ABSTRACT: In contrast to the interference avoidance paradigm that conventional wireless communication systems follow, the DARPA Interference Multiple Access (DIMA) Communications program intentionally structures multiple-access interference to enable high-capacity, low-latency, spread spectrum communications. The systempsilas adaptive multi-user detection (MUD) receiver algorithms enable the transmission of multiple data streams in the same time and frequency channel without need for centralized control of synchronization or power levels. This paper focuses on the DIMA system level implementation of the prototype radio network, along with the results from both non-real-time testing and real-time performance characterization efforts. Extensive simulations and non-real-time over-the-air testing helped to drive the design of a real-time MUD receiver implemented on a single FPGA. The Media Access Control Layer, implemented on a General Purpose Processor (GPP), facilitates intentional interference through a defined frame structure that also enables distributed synchronization and scheduling. During the real-time performance characterization period, the DIMA prototype network demonstrated 3.5 times the spectral efficiency of comparable 802.11 ad-hoc systems at low signal to noise ratios (SNRs). DIMA demonstrated up to 11x reductions in latency jitter in the same comparison. These gains can be leveraged in future military applications to provide increased capabilities and improved performance to the war fighter.Military Communications Conference, 2008. MILCOM 2008. IEEE; 12/2008
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ABSTRACT: In this paper we present a case for using new power-aware metrics for determining routes in wireless ad hoc networks. We present five different metrics based on battery power consumption at nodes. We show that using these metrics in a shortest-cost routing algorithm reduces the cost/packet of routing packets by 5-30% over shortest-hop routing (this cost reduction is on top of a 40-70% reduction in energy consumption obtained by using PAMAS, our MAC layer protocol). Furthermore, using these new metrics ensures that the mean time to node failure is increased significantly. An interesting property of using shortest-cost routing is that packet delays do not increase. Finally, we note that our new metrics can be used in most traditional routing protocols for ad hoc networks. 1