Offshore Bandwidth Boost - Technical whitepaper Page: 2
MCP solutions facilitate first class mobile telephony coverage, while ensuring that crewmembers can access the internet. The soluti-ons boast features that radically improve the data network, both by optimising throughput over sa-tellite, as well as bundling it with additional data links, creating a bandwidth boost.
MCP provides mobile base sta-tions on-board. Connection is made via the ships satellite link to public networks on shore
The solution meets the demands of the merchant marine and offshore markets for full GSM functionality. It is also designed to provide value, take up the mum of space and require mini-mal maintenance. Installation can be configured to cover the entire ship or selected areas, giving an optimal communications solution customised to individual vessel requirements.
The system complements VSAT and offers streamlined reporting, which reduces administrative time and costs. Crew and passengers that utilise MCP’s solution are conveniently billed by their own service provider.
Alternatively, they can be provi-ded with CrewSIM cards.
MCP’s repeater solutions provide land mobile coverage as far as 50 nautical miles (nm) out at sea, while improving the reach of oil rig base-stations (figure 2). The repeater is connected to the MCP indoor mobile network, which gives those inside the vessel increased access to land mobile networks. It is also conne-cted to the GSM modem as part of the multiple data link bundling, giving extended range of operati-on for this data coperati-onnectioperati-on boost service.
The repeater is automatically turned on and off according to the location of the ship, avoiding intrusive network interference when the vessel enters EEZ zones of countries that the repeater is not approved for.
MCP also provides the installati-on of wireless Internet, securing effective coverage for on-board locations.
MCP bandwidth boosters
MCP solutions optimise the on-board data network. Both corporate and welfare networks can be tuned and given different priorities and configurations.
MCP provides several bandwidth booster services, addressing all aspects of ship-to-shore data network issues, encompassing typical VSAT data link (1) cha-racteristics, as well as seamlessly adding multiple other data links (2) when available, and finally deploying IP traffic control (3) blocking bandwidth eaters.
Costly, outdated technology has restricted those wanting to communicate to and from
offshore supply vessels. Innovations from MCP enable the same mobile and data reach at
sea as onshore, with vastly reduced need for expensive satellite communications.
This whitepaper explains how ship-owners, crew and ICT-departments benefits from
te-chnology that reduces costs and yields new opportunities.
• Reliable phone service while at sea • 2G, EDGE and 3G support
• Compression technologies save money and resources
• Works seamlessly with all major cell phone carriers.
• Customer Console provide up-to-date information—check incoming and out-going call statistics, minutes used, data usage, customer service requests, and vessel locations
• Easily installed without disrupting ship operations.
• No maintenance required. MCP moni-tors and operates networks remotely along with any regulatory and legal challenges.
Figure 1: CellAtSea® mobile system and repeater
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1. VSAT data link
MCP offers Data Compression and TCP tuning, Adaptive For-ward Error Correction (FEC), Pac-ket Order Correction (POC), and various Quality of Service (QoS) and Priority adjustments.
MCP’s data compression saves 10-20% bandwidth on GSM data, 30-50% on mobile data, and between 20 and 50% bandwidth on mixed IP traffic. The selected compressi-on method is suitable to combine with FEC.
TCP tuning and POC
TCP protocol has a congestion avoidance mechanism based on acknowledging packets received, back to the transmitter. In long latency systems like satellite links the round trip time is high, typi-cally >500ms, due to the physical distance data has to travel. Thus the acknowledge packets sent frequently arrive too late, which TCP interprets as network con-gestion.
TCP will then quickly reduce the transmission rate to unblock congestion, before slowly building the rate up again. This results in low utilisation of the actual satellite link bandwidth. The MCP system adjusts TCP window sizes indicating how long to wait for acknowledge packets (acks), as well as providing selective acknowledgements over the sa-tellite link - a feature that causes most acks to return quickly on the local end of the satellite link. In addition, the system provides POC, rearranging received
pac-kets into the correct order be-fore providing them to the data network, streamlining the data and compensating for satellite link characteristics.
Forward Error Correction (FEC) ensures good communication even when packet losses are in the 1-10% range. By deploying link layer FEC, correcting the data before they are delivered to the transport layer, high bandwidth savings can be experienced. One also avoids transport level protocol retransmissions for any protocol and application over IP. Link layer FEC has a maximum effect at high bandwidth utilisa-tion and at high capacity links. This can be illustrated in Figure 3 where a given satellite link offers 2Mbps DL and the data network is trying to utilise all of that capa-city. It is not uncommon to expe-rience 1% packet loss on satellite links, but even if the loss is as low as 0.1% this causes a severe drop of throughput down to 0.75Mbps. When FEC is used it restores the data rate up to 1.8Mbps, with an example level of FEC redundan-cy packets of 1 for 8 normal IP packets.
Through the addition of more redundancy packets, for example 2 to 8, one can maintain reaso-nable throughput even at packet losses of 5%. Further from Figure 3, if the satellite link offers only 512kbps DL, FEC is less relevant. But if packet loss is higher than 0.3%, FEC again starts to become useful.
The addition of FEC error cor-rection packets means less real
data packets are submitted. As demonstrated by the example in Figure 3, for FEC at 1:8 levels this means 10% of the total bandwidth of 2Mbps. Link layer FEC is most effective by packet loss statisti-cally spread. This is more typical for satellite links. FEC is not as effective at burst loss of multiple packets, which is more typical for network congestions. The effects of FEC has been studied e.g. in , which suggests adapting the level of error correction packets to the level of packet loss. Adaptive FEC ensures that over-head from having FEC enabled is limited at low packet loss rates. At higher packet loss FEC over-head increases, but the recovery of packets increases even more, avoiding further retransmissions and the triggering of the TCP congestion avoidance mecha-nism, which would result in lower speed. Combining data compres-sion and FEC services yields posi-tive cross-effects, although these two services may be deployed separately.
Satellite link monitoring
Through real-time monitoring of satellite connections ship-ow-ners always have an overview of the quality of the VSAT provider service (Figure 4). This ensures that the quality is in accordance to the agreed SLA with the VSAT provider.
Figure 3: Throughput as function of packet loss
Figure 4: Satellite link quality monitoring console per ship
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2. Multiple Data Link
Bandwidth needs are always increasing and VSAT bandwidth upgrades are costly. MCP offers an alternative way - bundling mul-tiple data links together with the VSAT (Figure 5).
When a ship is in position to communicate with land-based or oil rig-based mobile data networks (2G/3G/4G), or at har-bour in the proximity of a WLAN access point, the MCP Multiple Data Link Bundling feature gives seamless network-access resul-ting in an additional bandwidth boost.
MCP default configures this fea-ture for flat priority between the different data links, except for 2G GPRS data link, which is used only as backup. This means all data links are used as available, including VSAT. Data links are selected in a round-robin way, per created IP session. There are op-tions to customise the bundling configuration based on low laten-cy, priority, overflow, persistence, least used, weighted balance, or enforcing.
The further away from the coast or oil rig, the less added speed will be provided on top of the VSAT link, as the land mobile
network’s signal strength diminis-hes.
A descriptive usage scenario of the MCP mobile system, including the MCP Mobile Data Link Bund-ling feature, is available from MCP. com.
Data link monitoringSome mobile subscriptions have data volume limitations. The MCP Multiple Data Link Bundling mechanism can be configured to automatically monitor data con-sumption and switch off the rela-ted data connection when volume limits are exceeded, to minimise cost and maximise speed.
3. IP traffic filtersThe final booster is IP traffic fil-tering, helping prevent the usage of “bandwidth eaters”, such as streaming, gaming, and downlo-ads (Figure 6).
This system monitors traffic as well as filtering and is highly con-figurable, adapting to the needs of the customer.
Traditional Wi-Fi management systems optimise bandwidth usage by white and black-listing webpages and apps. However, services like Skype and YouTube are using port hopping and other technical “tricks” to avoid blacklis-ting. MCP’s IP traffic control sys-tem is based on dynamic context based policy management. The IP traffic can be restricted based on ’white-list‘, ’black-list’, content, address, or port. Filtering can be set on user/group basis.
Facebook’s wall and chat fea-tures could be allowed, while more bandwidth intensive Face-book-applications, like games, are restricted. All video streaming could be restricted, as well as content categories like adult or gambling. Automatic SW updates can be restricted, or limited to certain times of day.
Some streaming protocols like RTP, which is frequently used by mobile phones, limit their band-width usage to a given fraction of the total available bandwidth. Other streaming services need 500Kbps and HD streaming requ-ires between 1.5 Mbps and 8 Mbps to buffer data faster than showing the content. Thus only one crew member using such services can easily congest the entire network. Firewall and virus detection The IP traffic filter also acts as a firewall. Viruses, Trojans, spyware and other kinds of malware are automatically stopped before the satellite link to avoid inefficient bandwidth usage. The anti-virus and threats filters are updated regularly.
Monitoring reports can be gene-rated on a weekly or monthly basis, listing most used services, applications and bandwidth
consumers. It is possible to report usage for each device or user, and even identify which devices are virus infected. MCP updates the Traffic Filter configuration based on customer request.
The innovative MCP technology empowers your crew with a vast set of mobile communication
channels in addition to the on board data networks (Ethernet and WiFi).
The system does not conflict with any corporate PBX and DECT telephony systems, but optimises data going over the satellite link, as well as offloading the satellite link by optionally providing other data carriers.
The system increases availability, uptime and performance of the total network. The result is higher quality services for crew, opera-tors and other guests on board - any time and at any location.
MCP bandwidth boosters benefits:
Satellite link tuning:
Data compression, adaptive FEC, POC and TCP tuning boosts bandwidth for the aggregated data traffic over satellite link. The combination mitigates the negative bandwidth effects characterizing VSAT data links.
Multiple data links benefits:
Added availability, uptime and increased bandwidth in coastal areas as well as near the oil rigs or in satellite- shadow. The function makes the data network on board more stable and efficient.
IP traffic filters benefits:
Controlling what services that are run on top of IP network. Helps to avoid uninte-ntional bandwidth outage, and reserve required resources to corporate network as well as provide suitable service level of the welfare network.
Figure 6: MCP bandwidth boosters and multiple data link bundling
 Bandwidth tradeoff between TCP and