Recent popularity of agile radio frequency transceivers, software defined radios, and large Field-Programmable Gate Array (FPGA) devices presents both opportunities and challenges in the tactical communications domain. Technology advances enable more complex communications systems, but also allow increasingly sophisticated threats to existing systems at faster rates. Traditional, stove-piped, special-purpose tactical waveform development techniques are not suited for this new environment, creating a clear need for rapid waveform design and deployment practices. The maturation of modular, evolvable design frameworks offers the flexibility to refresh system capabilities without requiring entire system overhauls. GNU Radio and Common-modern Hardware Integrated Library (CHlL) are two such frameworks that are intended for General Purpose Processor (GPP) and FPGA/ASIC deployment, respectively. In this paper, we outline an integrated approach for prototyping a surrogate tactical waveform using both the CHlL and GNU Radio frameworks, provide benchmarking results to highlight the implementation's configurability, and comment on lessons learned while interfacing both frameworks together.

Disruption/Delay tolerant networking (DTN) is a promising solution to mitigate the effects of periodic link outages that last seconds to minutes, which are prevalent in high capacity airborne tactical networks that are directional in nature and highly affected by aircraft body blockage. There are several considerations for applying the DTN Bundle Protocol (RFC 5050) in tactical edge networks which have ciphertext/plaintext boundaries resulting in multiple deployment options: 1) black-side DTN tunnel, 2) red-side DTN interface, 3) red-side DTN proxy, and DTN-enabled applications. Each of these approaches have benefits and limitations. In this paper, we present a DTN proxy implementation that can work on both red or black sides of tactical edge networks and show test results that help us better understand the capability of the approach, its limitations, and in what circumstances it is most appropriate. Through experimental and theoretical analysis, we show that TCP file transfer speed can be increased by up to 143.39% and 218% for two-hop and three-hop aerial backbone networks respectively when each link suffers 25% independent outage.

In this paper, we compare the proactive MANET routing schemes of OLSR and OSPF-MDR via high-fidelity simulation, and consider their suitability for large-scale airborne networks. A successful MANET routing scheme must be bandwidth efficient and robust to frequent topology changes. To assess the two protocols, we simulate them in networks with up to 400 mobile nodes, under a variety of network densities. We evaluate them on the basis of the amount of routing overhead generated, the rate of successful packet delivery, and the time it takes until all of the routing tables converge. We find that OLSR requires up to an order magnitude higher router overhead than OSPF-MDR, while providing only a marginal benefit in packet delivery success rates. The largest difference between the two protocols is the time it takes for their routing tables to converge in the presence of packet loss. OLSR has consistent convergence times for networks of all sizes, while the convergence time of OSPF-MDR increases with network size.

The desire for DoD communications systems to converge on an all-IP infrastructure, fueled by the increased usage of net-centric IP applications at the tactical edge have pushed research in maximizing bandwidth efficiency amidst a shrinking allocation of RF spectrum. One method of providing increased bandwidth efficiency (especially with the desire to move to IPv6), is the use of IP header compression (IPHC) techniques such as IP header compression (RFC2507), RObust Header Compression (ROHC-RFC5225), and others, to compress headers. Although widely used in one-hop cellular networks, many IPHC schemes today are stateful in that they build hop-by-hop compression state per flow. Maintaining this per-hop state per flow, however, becomes increasingly difficult in MANET environments where next-hop information is constantly changing. In this paper, we propose a shared-state/stateless IP header compression scheme tailored to MANET environments called MANET IP Header Compression (MIPHC). We show that although MIPHC does not achieve the same load reduction as ROHC for single-hop wireless networks, there are gains in MANET environments due to lack of need to build compression context on a hop-by-hop basis. MIPHC can also be combined with other protocols to compress higher layer headers.

The desire to increase bandwidth efficiency in an all-IP infrastructure in the presence of reduced spectrum and increasing demand for connectivity has led to several developments in IP header compression techniques. In recent years, there have been several IP header compression schemes developed in industry specifically for wireless networks including RObust Header Compression (ROHC) and IP Header Compression (RFC 2507). ROHC and IPHC (RFC 2507) have been adopted by several commercial cellular networks and military networks as one of the techniques for implementing IP header compression. In addition to ROHC and IPHC which were designed primarily for one-hop wireless networks, MANET IP Header Compression (MIPHC) was defined to help bridge the gap to multi-hop MANETs. To evaluate the effectiveness of IP header compression schemes on multi-hop MANETs and other networks, we implement simulation models of ROHC, IPHC, and MIPHC and evaluate their performance under various conditions in a mobile ad hoc network. The results show that although ROHC was designed specifically for one-hop cellular networks and context is required to be maintained per hop per IP flow, its performance is fairly good in multi-hop MANETs.

The desire for the cellular and wireless industry to converge on an all-IP infrastructure, fueled by the increased usage of mobile applications on smart phones and VoIP applications have pushed research in maximizing bandwidth efficiency amidst a shrinking allocation of RF spectrum. One method of providing increased bandwidth efficiency (especially with the desire to move to IPv6), is the use of RObust Header Compression (ROHC-RFC5225) to compress headers from the network layer and above into small identifiers before sending packets to the link layer. ROHCv1 and ROHCv2 have been adopted and is in the roadmaps for usage on High Speed Packet Access (HSPA), Long Term Evolution (LTE) and Evolution Data Optimized (EV-DO) mobile phone networks. Although the promise of significant bandwidth savings can be achieved using ROHC, the stateful nature of the protocol leads to potential compromises. In this paper, we examine three attacks on the ROHC protocol that result in denial of service and packet interception and their affect on networks that use ROHC to compress and decompress IP headers. Additionally, we propose three simple methods to mitigate the attacks.

In highly dynamic airborne networks, multi-hop routing becomes increasingly difficult due to high mobility, intermittent links and link quality, and the need to scale. Traditionally, airborne tactical networks have leveraged existing MANET proactive, reactive, and hybrid routing protocols with modifications for cross-layer information, to provide multihop routing. Although there has been some success with utilizing these protocols individually in airborne networks, a proper comparison of all types of MANET routing protocols at scale, with mobility patterns associated with airborne tactical networks, is lacking. In this paper, we compare a variety of proactive and reactive MANET routing protocols such as AODV, OLSR and OSPF-MDR, under relative node velocities and mobility patterns associated with airborne networks. Specifically, we evaluate each protocol in terms of routing overhead traffic, end-to-end message completion rate, and end-to-end delay, to examine performance vs. tradeoff.