WiFi: Mesh Network

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Mesh networking (topology) adalah salah satu jenis jaringan dimana setiap node di jaringan tidak hanya menerima atau mengirim data miliknya, tapi juga berfungsi sebagai relay untuk node yang lain. Dengan kata lain, setiap node bekerjasama untuk mengirimkan data di jaringan.

Sebuah jaringan mesh dapat di rancang menggunakan teknik flooding atau menggunakan teknik routing. Jika menggunakan teknik routing, maka message akan di kirim melalui sebuah jalur, dengan cara "loncat" dari satu node ke node yang lain sampai tujuan tercapai. Untuk menjamin keberadaan route / path, maka sebuah mekanisme routing harus memungkinkankan untuk terjadi sambungan terus menerus dan mengkonfigurasi secara automatis jika ada jalur yang rusak atau terblokir, menggunakan algoritma "self-healing" atau "memperbaiki diri sendiri". Sebuah jaringan mesh terjadi dimana semua node tersambung ke satu sama lain sebagai sebuah network yang saling tersambung.

Jaringan mesh dapat di lihat sebagai salah satu jenis jaringan ad-hoc. Mobile ad hoc network (MANET) dan jaringan mesh sangat erat satu sama lain, akan tetapi MANET harus dapat menyelesaikan masalah yang terjadi karena mobilitas node.

Kemampuan self-healing memungkin sebuah jaringan yang berbasis routing untuk tetap bekerja jika salah satu node rusak atau sambungan menjadi jelek. Akibatnya, jaringan ini umumnya sangat reliable, biasanya ada lebih dari satu sambungan antara sumber dan tujuan di jaringan. Meskipun skenario ini biasanya digunakan di wireless, konsep ini juga dapat digunakan di jaringan kabel maupun interaksi software.

Jaringan Wireless Mesh

Wireless mesh networks awalnya di kembangkan untuk aplikasi militer yang memang mempunyai arsitektur mesh. Sepuluh tahun belakangan, ukuran, biaya dan daya dari radio sudah sedemikian murah, sehingga memungkinkan semakin banyak radio yang dapat bergabung sebagai node mesh.

Tambahan radio dalam setiap node memungkinkan dia untuk mendukung banyak fungsi, seperti, akses bagi client, layanan backbone, dan scanning (dibutuhkan untuk handover kecepatan tinggi di aplikasi mobile). Di tambah lagi, dengan semakin kecil radio, semakin murah biaya, semakin kecil daya yang dibutuhkan membuat node mesh semakin modular - sebuah node atau sebuah device dapat berisi beberapa card radio atau modul, memungkinkan node untuk meng-custom fungsi dan frekuensi khusus.

Contoh

Di awal tahun 2007, sebuah perusahaan Amerika Meraki

launched a mini wireless mesh router. This is an example of a wireless mesh network (on a claimed speed of up to 50 megabits per second). The 802.11 radio within the Meraki Mini has been optimized for long-distance communication, providing coverage over 250 metres. This is an example of a single-radio mesh network being used within a community as opposed to multi-radio long range mesh networks like BelAir or MeshDynamics that provide multifunctional infrastructure.

The Naval Postgraduate School, Monterey CA, demonstrated a wireless mesh network for border security. In a pilot system, aerial cameras kept aloft by balloons relayed real time high resolution video to ground personnel via a mesh network.

An MIT Media Lab project has developed the XO-1 laptop or "OLPC"(One Laptop per Child) which is intended for disadvantaged schools in developing nations and uses mesh networking (based on the IEEE 802.11s standard) to create a robust and inexpensive infrastructure. The instantaneous connections made by the laptops are claimed by the project to reduce the need for an external infrastructure such as the Internet to reach all areas, because a connected node could share the connection with nodes nearby. A similar concept has also been implemented by Greenpacket with its application called SONbuddy.

In Cambridge, UK, on the 3rd June 2006, mesh networking was used at the “Strawberry Fair” to run mobile live television, radio and Internet services to an estimated 80,000 people.

The Champaign-Urbana Community Wireless Network (CUWiN) project is developing mesh networking software based on open source implementations of the Hazy-Sighted Link State Routing Protocol and Expected Transmission Count metric. Additionally, the Wireless Networking Group in the University of Illinois at Urbana-Champaign are developing a multichannel, multi-radio wireless mesh testbed, called Net-X as a proof of concept implementation of some of the multichannel protocols being developed in that group. The implementations are based on an architecture that allows some of the radios to switch channels to maintain network connectivity, and includes protocols for channel allocation and routing.

SMesh is an 802.11 multi-hop wireless mesh network developed by the Distributed System and Networks Lab at Johns Hopkins University. A fast handoff scheme allows mobile clients to roam in the network without interruption in connectivity, a feature suitable for real-time applications, such as VoIP.

Many mesh networks operate across multiple radio bands. For example Firetide and Wave Relay mesh networks have the option to communicate node to node on 5.2 GHz or 5.8 GHz, but communicate node to client on 2.4 GHz (802.11). This is accomplished using SDR (Software-Defined radio.)

The SolarMESH project examined the potential of powering 802.11-based mesh networks using solar power and rechargeable batteries. Legacy 802.11 access points were found to be inadequate due to the requirement that are continuously powered. The IEEE 802.11s standardization efforts are considering power save options, but solar-powered applications might involve single radio nodes where relay-link power saving will be inapplicable.

The WING project (sponsored by the Italian Ministry of University and Research and led by CREATE-NET and Technion) developed a set of novel algorithms and protocols for enabling wireless mesh networks as the standard access architecture for next generation Internet. Particular focus has been given to interference and traffic aware channel assignment, multi-radio/multi-interface support, and opportunistic scheduling and traffic aggregation in highly volatile environments.

Recent standards for wired communications have also incorporated concepts from Mesh Networking. An examples is ITU-T G.hn, a standard that specifies a high-speed (up to 1 Gigabit/s) local area network using existing home wiring (power lines, phone lines and coaxial cables). In noisy environments such as power lines (where signals can be heavily attenuated and corrupted by noise) it's common that mutual visibility between devices in a network is not complete. In those situations, one of the nodes has to act as a relay and forward messages between those nodes that cannot communicate directly, effectively creating a mesh network. In G.hn, relaying is performed at the Data Link Layer.

See also

Mesh network applications

Mesh network devices

Technical challenges

External links

Referensi

Pranala Menarik

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