In wireless wireless networks, it is very important to deal with cellular handheld (MS) handoffs between cells so that they can maintain continuous and QoS security. There are four main types of handoff protocols; Network Handheld Handoff (NCHO), Handheld Holder (MAHO), Soft Handoff (SHO) and Handheld Hand Control (MCHO). From NCHO to MCHO, management tests tend to spread the decision-making process, which helps to shorten handoff delays; However, while the deployment makes the measurements available to make a decision about handoff also reduced. Next, we present these four types of handoff systems.
NCHO is a central handoff protocol, as it is a network that makes a handoff decision based on measurements of the signal quality of the mobile station (MS) on a number of stations (BS). Specifically, if MS is measured to have lower marks in the old cell, but stronger signal in neighboring cell, then a handoff decision could be taken online to replace BS from the old cell into the new cell. Such a type of handoff generally takes 100-200 ms and produces a noticeable "pause" in the conversation. However, the overall delay of such handoffs is generally in the range of 5-10 s. Thus, this type of handoff is not suitable for a rapid environment and high density of users due to a delayed delay. NCHO is used in first generation analogue systems like AMPS.
MAHO distributes the handoff decision-making process. It is MS makes measurements, and the Mobile Switch Center (MSC) makes decisions about handoff. Compared to NCHO, this system has more distributed control, so it helps to improve the total number of handoffs, usually in the range of 1 s.
SHO is often used in conjunction with MAHO. Rather than immediately disconnect between MS and BS. In connection with handoff, a connection between MS and a new BS is first established, but follows an old connection between MS and the old terminal. Only after the new connection can be caused by data is the old connection issued. Thus, SHO is a "front-breaking mechanism". This system helps ensure consistent service levels, but it costs more capacity during the handoff (since two connections are established simultaneously).
NCHO, it is a MS that totally governs and takes decisions about handoff in the MCHO approach. MS continues to measure signal strength from all of the batches (BS) s. If MS finds that there is a new BS that has a stronger signal than an old BS, then it may be considered manually from the old BS to the new BS, provided certain marks have been reached. MCHO is the highest level of handoff decentralization, so it can have a very fast handoff speed, usually in a row of 0.1 s.
We have introduced four types of handoff systems that are widely used in wireless wireless networks. From centralization to distribution, network controlled handoff (NCHO) shows the highest networking, the absolute controller and decision-making on handoff, while the mobile controlled handoff (MCHO) gives full flexibility to MS to allow decision making on handoff. As a result, distribution methods show a very fast handoff rate, but centralized methods usually take a much longer time. In modern wireless wireless networks, direct communication systems are widely used for good flexibility and fast speeds.
This article was submitted by http://www.ylesstech.com .
Source by David Chow