MiWi Protocol Stack: Wireless Network Communication Explained

Introduction

In today’s interconnected world, wireless communication plays a pivotal role in enabling seamless data transfer and device interaction. The MiWi protocol stack is a lightweight, efficient solution tailored for low-power wireless networks. Designed by Microchip Technology, it simplifies the communication needs of Internet of Things (IoT) devices and automation systems.

This guide explores the fundamentals of the MiWi protocol stack, its structure, and its role in enhancing wireless network communication. The Microchip-developed MiWi™ protocol is very simple and used for short-distance communication. It supports low data rates and helps in creating low-cost networks.

MiWi is the short form of the Microchip Wireless networking protocol stack. Initially, the MiWi protocol was developed for WPAN-based networks. Later on, it was enhanced to support Microchip-designed RF transceivers.

This MiWi protocol is one of the alternatives used as wireless communication. MiWi Protocol serves small-size networks with small applications that require few hops between them.

All the wireless protocols are supported in the MiWi™ Development Environment. MiWi uses the MiMAC interface, which helps to communicate with RF transceivers developed by Microchip. It uses the MiApp interface in order to interact with the application layer.

MiWi protocol supports all the Microchip proprietary RF transceivers working on different bands. The following table mentions features of the MiWi protocol.

Let us understand terminologies used in MiWi Protocol such as “cluster” and “socket”.

“Cluster” in MiWi refers to a group of nodes that will form a network. The cluster can have a maximum of 3 nodes. It is controlled by a single clusterhead. Here, the clusterhead functions as a PAN coordinator. The other term “socket” refers to a virtual connection between two MiWi devices. By using the concept of sockets, nodes in the MiWi network will find communication partners dynamically, even without any information about them.

The protocol uses an acknowledged data transfer mechanism in the MAC layer.

In the MiWi protocol, there are three devices based on their individual functions in the network, namely: PAN Coordinator, Coordinator, and End Device. Following table-2 mentions their details.

The PAN coordinator is the device that starts the network. The PAN coordinator also selects the channel and the PAN ID of the network. All other network devices wanting to join onto the PAN need to obey the instructions of the PAN coordinator. There are three different kinds of configurations that exist in a MiWi network viz. star, cluster tree, and mesh type. The same have been depicted in the figure-1.

Before we understand the MiWi protocol frame, let us understand three address types used in the MiWi network, viz. EUI, PANID, and short address.

• EUI: This is a globally unique address of size 8 bytes. It is the short form of Extended Organizationally Unique Identifier.
• PANID: This is the address that defines a group of nodes. It is 16 bits in size. All the nodes in the personal area network share the same common PAN-ID.
• Short address: This 16-bit address is used as the device address, and it is assigned by its parent. This address is unique within a PAN, and it is used for addressing and messaging purposes within a PAN network. The PAN coordinator always has an address of 0000h. All other addresses are taken care of by the coordinator.

The header of the MiWi protocol frame consists of the following fields:

• Hops: This number indicates the number of hops. It indicates the hops through which the packet is allowed to be re-transmitted.
• Frame Control: This bitmap defines the behavior of the MiWi packet. It is of 1-byte length.
• Dest PANID: Indicates the PAN-ID of the final destination node. It is 2 bytes in size in the MiWi protocol frame.
• Dest Short Address: The short address of the final destination node. It is 2 bytes in size.
• Source PANID: The PAN-ID of the node which originated the packet. It is 2 bytes in size.
• Source Short Address: The short address of the node which originated the packet (2 bytes).
• Sequence Number: A sequence number which is used to track the status of the packets as they travel through the network till the destination. It is 1 byte in size.
• Report Type and Report ID: The protocol carries packets between the devices using special packets known as “reports”. The MiWi protocol allows the implementation of 256 Report Types. There are 256 different Report IDs that can be assigned for each Report Type.

Conclusion

The MiWi protocol stack is an invaluable asset in the world of wireless communication, offering a streamlined and cost-effective solution for low-power, short-range networks. Its robust features and compatibility with IoT applications make it a preferred choice for developers aiming to build scalable and reliable wireless systems. As technology evolves, MiWi continues to empower industries by enabling smarter, more connected solutions.