HF/DF 위성통신의 대안: 4G LTE 서비스와 단파통신

[위종민]

중국과의 분쟁에서 위성이 파괴되거나 무력화돼 위성통신을 사용할 수 없는 경우에 대비해 4G LTE나 전리층에 반사돼 장거리 통신이 가능한(대역폭은 비교할 수 없이 느리지만) HF 통신을 활용해야 한다는 주장이네요. LTE는 지상 차량이나 드론, 항공기나 풍선에 LTE 중계기를 배치해 전시에도 LTE 통신을 사용할 수 있을 거라고 합니다. 

호주군은 20세기 말까지 HF 통신을 폭넓게 운용했었다고 합니다. 당시 쌓였던 전리층 예측 차트에 기반해 주파수를 선택하고, 수신국과의 거리와 방향을 고려해 안테나를 고르는 등의 노하우는 많이 실전됐는데 이를 부활시켜야 한다고.. HF 통신 기술도 많이 발전해 최신 HF 무전기의 속도는 240,000bps라고 합니다. (= 240kbps = 0.24 Mbps 네요. ) 현재 호주군의 BTN (  battlefield telecommunications network )과 TCN ( tactical communications network )은 UHF와 VHF 무선기 의존도가 높은데, 이 장비들은 전자전 위협을 거의 받지 않는 저강도 분쟁 운용을 전제로 설계됐다고 합니다. 4G LTE와 HF 라디오는 BTN과 TCN에 쉽게 적용할 수 있다고 하고요. 

카톡이 진짜 정식 통신수단으로 채택되는 모습을 볼 수 있을지도 ㄷㄷㄷ

Satellite communications are vulnerable, but good alternatives are available | The Strategist (aspistrategist.org.au)

Satellite communications are vulnerable, but good alternatives are available

14 Oct 2024|Alan Seymour

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What happens if space, crucial for Australian Defence Force missions, becomes inaccessible during a major conflict? If satellite communications and support are disabled or destroyed, existing critical communications networks will be lost.

The data flow that fills the ADF’s common operating picture would dwindle to intermittent trickles. Tactical commanders would be starved of timely information and lose confidence in the reliability and accuracy of what they receive. Distant commanders would struggle to keep up with what’s going on and would lose much of their ability to direct and coordinate forces.

There are alternatives. The main one pre-dates satellites, high-frequency (HF) radio. The other is to use the ubiquitous civilian 4G/LTE standard of cellular communications. Both can provide effective links across a battlefield and back to the command, especially for forces deployed in archipelagic and littoral settings.

HF radio offers a direct replacement for satellite communications. Unlike other radios that operate in higher frequencies, HF is not limited to line of sight, because (depending on the antenna selected) it can follow the surface (as groundwave) or bounce off the ionosphere (as skywave). So, units carrying HF radios can send and receive data over hundreds, thousands or even tens of thousands of kilometres. HF’s data rate is nothing like what is available from satellites, but, with suitable prioritisation of traffic, can nonetheless support operations.

As for 4G/LTE, we are familiar in the civilian world with fixed cellular transceivers on buildings and masts. But this capability can also be replicated in ground vehicles, loitering drones, aircraft, balloons or even soldiers’ backpacks to provide a tactical variant.

A ground force using tactical 4G/LTE can set up its own local cellular communications network. That could be connected to an HF link to reach farther—say, to command or to coalition or mission partner forces—or it might use civilian long-haul connections, such as cable, by patching into a nearby commercial 4G/LTE network.

Satellites have made life easier for the ADF, especially in deployed environments, but they bring a critical danger of overreliance. They can be destroyed or incapacitated—by China, for example.

Our reliance on satellite communications has not been threatened in Australia’s wars of choice in the past few decades. But it is now our Achilles heel.

Defence also relies on satellites for positioning, navigation and timing services. Alternatives and reduced reliance will be needed there, too, although HF and tactical 4G/LTE cannot provide the same information.

The ADF used HF extensively until the end of the 20th century for tactical and strategic purposes. Defence operators were highly proficient in choosing frequencies, based on interpretation of ionosphere prediction charts, and in considering distance and direction to receiving stations as they chose antennas. Those skills have diminished. They can and should be resurrected.

Since those days, technical advances in HF radios have included Automatic Link Establishment (ALE) to quickly initiate and maintain communications. When Defence last relied on HF radio for communications, data rates were very low; modern HF radios using wideband waveforms offer up to 240,000 bps, fast enough to carry the data that now relies on satellites, even voice. And HF needs no infrastructure.

The current structure of Australia’s battlefield telecommunications network (BTN) and the tactical communications network (TCN) ‘reflects a bygone era’, in the words of the Strategic Defence Review. Mostly using UHF and VHF radio, it relies on equipment that was designed for and deployed in low intensity conflicts, in which the enemy could not exploit our vulnerabilities.

Those systems will continue to have their place, but they urgently need complementing with more layers of flexibility, resilience and backup.

Adding to the challenge, forces in a major war would have to be mobile and dispersed, in part to avoid creating conspicuous electromagnetic signatures. In the southwest Pacific, geography alone dictates the necessity of spreading combat elements thinly. Greater distances between units, steep terrain and dense foliage will make communication more difficult.

Tactical HF communications and tactical 4G/LTE systems can easily be meshed into the TCN, the BTN or civil communications infrastructure. They both enable robust, infrastructure-independent voice and data communication—within units deployed in a theatre, between them and to more distant parts of the ADF.

To reduce exposure to an enemy detecting and exploiting signals, the ADF should consider high speed, or burst, transmission and broadcast capabilities in HF.  This has all been done before, though it seems the skills have been forgotten.

In pursuit of enhanced mobility and the dispersion of combat and support forces, the ADF will need compact HF and 4G/LTE communications equipment that needs only low power supply. It should also be based on civil equipment with dual use technology and be proven, rugged, reliable, inexpensive and therefore abundant. As far as possible, open technical standards should be used and proprietary material avoided, to enable broader integration of technology, to provide flexibility and to reduce cost.

The equipment must be interoperable with existing ADF systems and with those of our allies, which can be achieved through software-enabled gateways.

Military use of 4G/LTE offers a special advantage: if it integrates into civilian cellular networks, its signals blend into the background electromagnetic environment, reducing the risk of detection.

Use of tactical 4G/LTE broadens the range of equipment that can be used to any iOS or Android device, with separate military grade encryption enabled. A tactical 4G/LTE system can also control robotic and autonomous systems in the field, again providing an alternative to satellite connections.

These alternatives to satellites are available now. And the capability to build HF and 4G/LTE communications systems of moderate cost is already in Australia, with a secure, resilient supply chain.

The threat of severe military debilitation through loss of satellite links demands that the alternatives be adopted.

[백선호]

통신위성이 없을 때는 지휘함에 커다란 HF 안테나가 달려있었죠.

https://cafe.daum.net/NTDS/51Tm/66

[위종민]

단파통신은 HF/DF를 통한 위치 노출 위협에 취약한데 그냥 위성통신용 위성을 많이 쏘아올리는 게 낫지 않을까 싶기도... ㅎㅎㅎ

[백선호]

Saipan형 경항모를 개조한 지휘함 Wright입니다.

https://en.wikipedia.org/wiki/USS_Wright_(CVL-49)#Reclassification