Co-existence between unlicensed networks that share a spectrum spatio-temporally with terrestrial (e.g., Air Traffic Control) and shipborne radars1 in 3 GHz band is attracting significant interest. Similar to every primary-secondary coexistence scenario, interference from unlicensed devices to a primary receiver must be within acceptable bounds. In this work, we formulate the spectrum sharing problem between a pulsed, search radar (primary) and 802.11 wireless local area network (WLAN) as the secondary.We compute the protection region for such a search radar for 1) a single secondary user (initially) as well as 2) a random spatial distribution of multiple secondary users. Furthermore, we also analyze the interference to the Wi-Fi devices from the radar's transmissions to estimate the impact on achievable WLAN throughput as a function of distance to the primary radar.
There is growing interest in radar spectrum sharing from both regulators and researchers @cite_13 @cite_20 @cite_23 @cite_16 @cite_31 @cite_12 @cite_7 @cite_22 @cite_25 @cite_3 @cite_19 @cite_9 @cite_1 @cite_28 @cite_21 @cite_11 @cite_24 @cite_17 . SSPARC program from DARPA @cite_20 is a good example that seeks to support two types of sharing: a) Military military sharing between military radars and military communication systems to increase capabilities of both and b) Military commercial sharing between military radars and commercial communication systems to preserve radar capabilities while meeting the need for increased capacity of commercial networks.
@cite_25 @cite_22 @cite_7 @cite_28 @cite_9 @cite_21 @cite_1 @cite_17 @cite_3 @cite_24 @cite_19 @cite_23 @cite_31 @cite_16 @cite_13 @cite_12 @cite_20 @cite_11
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This paper considers opportunistic primary-secondary spectrum sharing when the primary is a rotating radar. A secondary device is allowed to transmit when its resulting interference will not exceed the radar's tolerable level, in contrast to current approaches that prohibit secondary transmissions if radar signals are detected at any time. We consider the case where an OFDMA based secondary system operates in non-contiguous cells, as might occur with a broadband hotspot service, or a cellular system that uses spectrum shared with radar to supplement its dedicated spectrum. It is shown that even fairly close to a radar, extensive secondary transmissions are possible, although with some interruptions and fluctuations as the radar rotates. For example, at 27 of the distance at which secondary transmissions will not affect the radar, on average, the achievable secondary data rates in down- and upstreams are around 100 and 63 of the one that will be achieved in dedicated spectrum, respectively. Moreover, extensive secondary transmissions are still possible even at different values of key system parameters, including cell radius, transmit power, tolerable interference level, and radar rotating period. By evaluating quality of service, it is found that spectrum shared with radar could be used efficiently for applications such as non-interactive video on demand, peer-to-peer file sharing, file transfers, automatic meter reading, and web browsing, but not for applications such as real-time transfers of small files and VoIP. This paper considers gray-space spectrum sharing when rotating radars are primary spectrum users, and multiple cells from one or more cellular networks are secondary users. A cellular network may share spectrum to supplement its dedicated spectrum, or provide a broadband hotspot service. A secondary device is allowed to transmit as long as cumulative interference is not harmful to nearby radars, probably because no radar is pointing its directional antenna at the device at this moment. This paper presents mechanisms that would support such sharing, and quantifies performance when spectrum is considered 100 utilized under traditional spectrum management. It is shown that the sharing allows cells to sustain significant mean data rates. For example, if 5 of a cellular network's cells need more capacity than dedicated spectrum can provide, a cell can get almost 1.2 bps Hz on average from shared spectrum. By evaluating quality of service, it is found that shared spectrum could be used efficiently for applications such as non-interactive video streaming, peer-to-peer file sharing, large file transfers, and web browsing, but not for applications such as real-time transfers of small files, and VoIP. Abstract This dissertation considers gray-space primary-secondary spectrum sharing, in which secondary devices are allowed to transmit when primary transmissions are strong enough that additional interference is tolerable. Various novel sharing mechanisms are proposed for two different types of primary system: cellular systems, and rotating radars. Both cases when primary and secondary systems cooperate (cooperative sharing), and when they do not (coexistent sharing) are considered. Even in the scenario where radars are densely packed, a secondary transmitter can get almost 1.2 bps Hz on average, when 5 of the transmitters are competing for the shared spectrum. One also shows the potential of sharing models in which a secondary system has information about a primary system, but does not cooperate in real time. It is found that even with fluctuations and interruptions in secondary transmissions while radars rotate, the shared spectrum could be used efficiently for applications that generate much of the traffic on mobile Internet, but not for real-time. For sharing with cellular systems, the efficiency of cooperative and coexistent sharing is compared. When both achievable secondary transmissions and primary power consumption are of concern, coexistent sharing is found to be as effective as cooperative sharing. The lack of available unlicensed spectrum together with the increasing spectrum demand by multimedia applications has resulted in a spectrum scarcity problem, which affects satellite communications (SatCom) as well as terrestrial systems. The goal of this paper is to propose resource allocation (RA) techniques, i.e., carrier, power, and bandwidth allocation, for a cognitive spectrum utilization scenario where the satellite system aims at exploiting the spectrum allocated to terrestrial networks as the incumbent users without imposing harmful interference to them. In particular, we focus on the microwave frequency bands 17.7–19.7 GHz for the cognitive satellite downlink and 27.5–29.5 GHz for the cognitive satellite uplink, although the proposed techniques can be easily extended to other bands. In the first case, assuming that the satellite terminals are equipped with multiple low block noise converters (LNB), we propose a joint beamforming and carrier allocation scheme to enable cognitive space-to-Earth communications in the shared spectrum where fixed service (FS) microwave links have priority of operation. In the second case, however, the cognitive satellite uplink should not cause harmful interference to the incumbent FS system. For the latter, we propose a joint power and carrier allocation (JPCA) strategy followed by a bandwidth allocation scheme, which guarantees protection of the terrestrial FS system while maximizing the satellite total throughput. The proposed cognitive satellite exploitation techniques are validated with numerical simulations considering realistic system parameters. It is shown that the proposed cognitive exploitation framework represents a promising approach for enhancing the throughput of conventional satellite systems.