WELCOME TO THE SEMINARON
Introduction Mesh Radio is a new Broadband Fixed Wireless Access architecture that avoids the limitations of point to multi-point systems. A series of point-topoint links are set up between nodes mounted on customers homes, avoiding the cost of conventional base stations. The use of directional antennas reduces the power requirements and increases spectrum efficiency.
Networks grow to meet demand and can achieve a higher penetration over a larger geographic area than other systems. Mesh Radio could provide a platform for residential broadband that is practical in suburban and semi-rural areas if small, low cost nodes can be implemented. It would therefore give significant economic benefits in any country that implements it.
Mesh Radio is a new approach to Broadband Fixed Wireless Access (BFWA) that avoids the limitations of point to multi-point delivery. It could provide a cheaper 3rd Way to implement residential broadband that is also independent of any existing network operator or service provider. Instead of connecting each subscriber individually to a central provider, each is linked to several other subscribers nearby by lowpower radio transmitters; these in turn are connected to others, forming a network, or mesh, of radio interconnections that at some point links back to the central transmitter Mesh networks may involve either fixed or mobile devices. The principle is similar to the way packets go around the Internet, data will hop from one device to another until it reaches its destination.
Dynamic routing capabilities included in each device allow this to happen
Point to Point Topology The most basic broadband wireless architecture consists of two buildings connected directly to one another through a point-to-point (PtP) communications link. For situations where long-distance links are required, a PtP architecture may be the best solution.
When highly directional antennas are used, PtP links of 25 miles or more may be achieved with unlicensed broadband wireless equipment. A PtP topology will also typically provide the highest data rates because the available bandwidth doesn't need to be shared by more than two buildings.
A simple PtP link can also function as a reliable backup, where a wired connection already exists between buildings Although a PtP topology may be the right choice for small projects, it does not scale as well as other network topologies
Point to Multipoint Topology
A point-to-multipoint topology (PtMP) allows multiple remote buildings to share a connection back to a single, central building, commonly referred to as a base station. PtMP installations scale more easily than PtP because as new buildings are added to the network, no additional equipment or modifications are required at the base station. It is a requirement that each remote location have a clear LOS to the base station, so by itself, a PtMP network will not scale infinitely. Coverage of buildings over a wide geographic area, or an area with especially hilly terrain, may require a combination of multiple base stations with PtP links used as a backbone to interconnect the different PtMP networks
In addition to potential LOS problems, when traffic loads are heavy, multiple remote sites can attempt to simultaneously transmit information to the base station. Commonly referred to as "hidden transmitter interference," this causes interference to each transmission and slows down the broadband wireless network for everyone connected
Mesh Topology Mesh topology networks, sometimes referred to as peer-to-peer or multipoint-to-multipoint, offer significant benefits over PtP and PtMP topologies. In addition to being the most flexible broadband wireless topology, mesh technology: (1) enables network expansion; (2) provides a selfhealing architecture; (3) reduces implementation and operating costs; and (4) facilitates mobile applications.
Taxonomy of Sorts for Mesh Radio Dynamic/self-organizing/adaptive or static/deterministic Infrastructure, client or hybrid Fixed or mobile
Mesh Radio Architecture
Trunk Network Connection Points (TNCPs) link the radio access Mesh to the trunk communications network. Each of the TNCPs will serve a number (typically 3or 4) of Mesh Insertion Points.
These consist of a standard Customer Node (CN),which can set up connections to other customers, and equipment for multiplexing the signals to and from that customer node onto a link to the TNCP A Customer Node is installed at each customers premises. It not only provides service for that customer but also handles transit traffic from other customers. It consists of an outdoor radio unit and an indoor service presentation unit that provides the interface between the Mesh and the customers computer and phone systems The Mesh will also include a number of Seed Nodes (SNs). These are the same as the customer Nodes except that there are no customers connected to them
Advantages and Disadvantages of Mesh Radio Fewer central stations, Non-line-of-sight
NLOS configurations are easy to build out of meshes, so the linear nature of radio propagation isn't really a factor in meshes of any size.
Reliability is improved just because the network is structured as a
No need for "high Sites": Mesh Radio offers excellent coverage without requiring the use of "high sites." It is no longer necessary to deploy network connection points on the highest buildings or hilltops
Minimum upfront network investment for deployment With traditional fixed wireless systems, coverage, even to a few subscribers, depends on installing a significant number of base stations, so that an operator is faced with high initial costs when network revenues are lowest. With Mesh Radio new customers can be connected with a very low density of deployed 'seed' nodes, which provide initial coverage Robustness: Mesh is more robust than single-hop networks because it is not dependent on the performance of one node for its operation In mesh network architecture, if the nearest AP is down or there is localized interference, the network will continue to operate; data will simply be routed along an alternate path
Fault-tolerance, Self-healing architecture Meshes are very adaptable to failures in nodes or dropouts in radio coverage - traffic is simply re-routed dynamically. Each mesh node is aware of the primary optimal path, the secondary path, and every tertiary path a packet may follow to reach its intended destination
Higher bandwidth: One way to get more bandwidth out of the network, is to transmit data across multiple short hops. That's what a mesh network does. Additionally, because little power is required to transmit data over short distances, a mesh network can support higher bandwidth overall despite FCC regulations that limit maximum transmission power.
Spatial reuse: Spatial reuse is another benefit of mesh over single-hop networks. As noted earlier, in a single-hop network, devices must share an AP.
If several devices attempt to access the network at once, a virtual traffic jam occurs and the system slows
Spectrally efficient: Mesh radio is also far more spectrally efficient than point to multi-point systems, because the 'narrow' beams are much less likely to interfere with each other. The spectrum can therefore be re-used over and over in any area This means that, in any given spectrum allocation, up to ten times as many customers can be served at the same data rate compared with point to multi-point
Adaptive backhaul provisioning: One of the best features of a Mesh Radio is the lack of the requirement to provide a wired backhaul connection to every node. Rather, user traffic is relayed over the air between nodes until it reaches its destination or a node with a connection to another network (like the Internet). Thus, one could deploy, for example, a Wi-Fi mesh to provide service over a large geographic area, but only very limited backhaul initially
Power: The substrate nodes of a mesh network can be built with extremely low power requirements, meaning that they can be deployed as completely autonomous units with solar, wind, or hydro power.
Other Advantages Integration Reality fit Network Expansion
Conclusion Mesh Radio has significant benefits compared with PMP systems which come about through the use of directional antennas to set up a series of point-to-point links between nodes on customers homes
Mesh Radio could provide a 3rd platform for residential broadband to compete with cable and ADSL in urban areas that is also practical in suburban and semi-rural areas.Mesh Radio is completely new and it can be introduced independently of any existing network or operator The UK Government is keen to role out BFWA and the Radiocoms Agency is consulting on the use of the 40GHz band Even if it takes longer Mesh Radio will eventually happen and companies that stand to gain from its introduction should start to actively support its development.
References IEEE Wireless Communications,Oct 2003,Vol 10, No.5 IEEE Microwave Magazine,Vol 2,No 2,June 2001 IEEE Spectrum,June 2002 New Scientist Magazine,Nov 2001 www.meshradio.co.uk www.radiantnetworks.com www.broadcastapers.com www.broadbandmag.co.uk www.itti.com www.seminarsonly.com