Hybrid wireless protocols

Hybrid Wireless Network Protocols

Prepared by :- Mohammad Abdelhadi Mohammad Mustafa

Khaled Melhem

Outline :-

● Introduction.

● What is Hybrid Wireless Network.

● Proposed Protocols.● One hop Direct transmission.● Two hop Direct transmission.● Handoff Procedures.

● Simulation Results.

Introduction.● Wireless networks are of two types :-

● Base station-Oriented Wireless Network.○ Single-hop that requires fixed Base Station.○ Better performance.○ More Reliable.

● Ad Hoc Wireless Network.

○ Doesn't have any centralized administration.○ MHs depend on each other for communication.○ Low cost.○ High flexibility.○ Bandwidth usage and battery power consumption are

more efficient.

Introduction● Problems in BS-oriented wireless network.

○ BS failure problem

Introduction● Problems in Ad Hoc Wireless Networks:-

○ Rerouting caused by mobility. ● Disrupted Connection.

What is the Hybrid Wireless Network?

● Hybrid Wireless Network can act as a bs-oriented or ad hoc network at any given time according to the environment conditions.

● Made by adding Base stations to Ad hoc Network.● Has the advantages of both Ad-hoc and Base stations.● Mobile nodes communicate with each other using Ad Hoc

mode when they are in range, and use basestation to communicate when they are out of range.

● More efficient and reliable.● Flexible with seamless handover.

What is the Hybrid Wireless Network?

Proposed Protocols

● The Protocol for One-Hop Direct Transmission.

● The Protocol for Two-Hop Direct Transmission.

Direct Transmission

● Is the situation where two MHs communicate directly or use a third MH as a relay without the help of base station.

● The sender broadcasts the connection request message.● All devices within the sender's signal covering area would

receive this message ( including the BS).● Each MH receiving the message will check the destination

ID.● If the destination ID matches itself, The transmission

procedure begins.● When the destination moves out of the covering area, the

BS would have to take over (BS-Oriented Mode)

The Protocol for One-Hop Direct Transmission.

● Sender broadcast a SEARCH message.● If the receiver is within the range and finds out the

destination is itself, it responds with ACK message to the sender.

● The BS also receives the SEARCH message and it sends the SETUP message to the destination.

● if the destination sends the DIRECT message to the BS, the communication will be direct between MHs.

● Otherwise, if the destination sends an ACCEPT message to the BS, the communication will be BS-oriented mod.

● The Continuity of the communication of the two modes depends on the distance between the communicating pair.

One-hop direct transmission mode

The BS-oriented mode

Handoff Procedure

● Direct transmission mode:○ if the destination detects that the signal strength is less

than the threshold value, handoff must be executed.○ The destination sends the CHANGE message to its

sender.○ The sender receives the CHANGE message and it sends

the SEARCH message again, then BS-oriented mode will be used or two-hop mode.

Handoff Procedure

● BS to One-hop direct transmission:○ If the receiver detects that it is within the coverage region

of the sender's signal and the signal is strong enough, it has the option to switch from the BS-oriented.

○ The receiver sends the CHANGE request to the sender.○ The sender sends the SEARCH message out.....Direct

transmission steps.○ After the sender receives the ACCEPT message from the

receiver, it sends a TearDown message to the BS and breaks the connection.

BS-oriented handoff

Protocols for Two-Hop Direct Transmission Mode

● Cover wider area than the one-hop.● allow two MHs to communicate through a third MH acting as

a relay.● Each MH must implement a Neighbor Database.● A disrupted connection could occur.● Two is the optimal number for hops to avoid the routing

problems that could occur with more than two hops.

Two-Hop Direct Transmission Mode

● This situation happens when the communicating pair are both within an intermediate's coverage area.

● The sender transmits data to the receiver through an intermediate MH.

● If a MH is in the sender range there are two cases:○ When it is the receiver, it sends ACCEPT message back

(One-hop direct transmission).○ If it is NOT the receiver, it will check the neighbor data

base, if the destination is in its data base, it forward the SETUP message, and sends ACCEPT back to the sender if the connection is accepted.

Two-Hop Direct Transmission Mode

● The destination only accept one copy of the SETUP message.

● At the same time, the BS would receive the SEARCH

message. It queries the MH and sends the SETUP message to the destination. For direct transmission, the destination receives the SETUP message and sends the DIRECT message to its BS. Otherwise, the destination would accept the connection from the base station.

Two-Hop Direct Transmission Mode

Handoff Procedure

● if the destination or the intermediate node finds that the strength of the signal is less than a critical value, the handoff procedure is requested and executed at this time. The system will try to find another direct transmission path.

● If a direct transmission path is not found, the BS-oriented mode will take over. The handoff procedures are listed as follows.○ The destination or intermediate node sends the

CHANGE message to the sender for changing connection.

○ As the sender received theCHANGE request, it re-initiates the connection by sending out SEARCH. The next several steps are the same as in the initial connection setup.

Simulation Results

Simulation Results

Thank you for listening!Any Questions?