Non TCP/IP Wireless Protocols

Protocols designed for specific low-power, short-range use cases. TCP/IP carries too high a footprint for many embedded and sensor applications. Protocol selection is application-driven: each trades data rate, range, and power against complexity.

Legacy non-IP protocols: SNA, DECNet, Novell Netware, NetBEUI, WAP.
Current relevant protocols: Bluetooth, ZigBee, NFC, Fiber Channel.

Bluetooth

Short-range wireless protocol for cable replacement, multiparty data exchange, and personal trusted device connectivity. Developed by Ericsson; managed by the Bluetooth Special Interest Group. Standardized as IEEE 802.15.1. Originally a wireless alternative to RS-232 data cables.

• Band
  2.4–2.48 GHz (ISM).
• Range
  ~10 m.
• Bandwidth
  2.1 Mbps shared (v2.0).
• Version 4.0 variants
  Classic Bluetooth, Bluetooth High Speed (Wi-Fi-based), Bluetooth Low Energy (BLE).

Protocol Stack

Divided into a Transport Protocol group and a Middleware Protocol group.

Transport layers, bottom to top:

• Bluetooth Radio
  Radio signal modulation and transmission.
• Baseband
  Frequency-hopping and time-division multiplexing between master and slaves.
• Link Manager Protocol (LMP)
  Logical channel establishment, authentication, power management.
• Host Controller Interface (HCI)
  Software interface to baseband and link manager. Exposes hardware status and registers.
• L2CAP (Logical Link Control and Adaptation Protocol)
  Multiplexes multiple logical connections. Provides segmentation and reassembly of on-air packets. Primary layer from the application developer’s perspective.

Middleware layers:

• RFCOMM
  Cable replacement protocol. Emulates EIA-232 (RS-232) serial interface.
• SDP (Service Discovery Protocol)
  Discovers services offered by other Bluetooth devices.
• TCS-BIN (Telephony Control Specification, Binary)
  Establishes speech and data calls between master and slave.
• OBEX (Object Exchange Protocol)
  Exchanges structured data objects such as calendars and vCards.
• Audio
  Supports audio communication directly on top of Baseband.

Network Topology

Piconet

Basic Bluetooth network unit. All communication goes through the master. No direct slave-to-slave communication.

• Up to 7 active slaves.
• Up to 255 parked (inactive) slaves.

Scatternet

Formed by connecting 2+ piconets. A device can act as slave in one piconet and master in another simultaneously.

Profiles

A profile is a set of application-layer protocols defining behaviors for a specific use case. Profiles reside on top of the Bluetooth core specification.

Examples:

• HFP
  Hands-Free Profile.
• BPP
  Basic Printing Profile.
• AVRCP
  Audio/Video Remote Control Profile.
• FTP
  File Transfer Profile.
• HID
  Human Interface Device Profile.
• PAN
  Personal Area Networking Profile.
• GOEP
  Generic Object Exchange Profile (uses OBEX).

Near Field Communication

Also known as NFC. Short-range wireless communication based on magnetic field induction between readers and tags in RFID systems. Initiated in 2004 by Nokia, Philips, and Sony.

• Frequency
  13.56 MHz.
• Range
  10 cm or less.
• Data rate
  106–424 Kbps.

Advantages: low cost, low energy, no search/pair procedure, minimal configuration, better security.
Limitations: low range, low data rate.

Used in: mobile payments, public transportation, mobile identification, mobile marketing, social networking, check-in.

Modes of Operation

• Active Mode
  Both devices generate electromagnetic fields and exchange data.
• Passive Mode
  One active device generates the field. The passive device uses that field to exchange data.

Application interaction patterns: Touch & Go, Touch & Confirm, Touch & Connect.

Protocol Stack

Three operational modes, each with distinct stack components:

• Card Emulation Mode
  Smart card capability for mobile devices.
• Peer-to-Peer Mode
  LLCP (Logical Link Control Protocol) with NFC Forum Protocol Bindings (IP, OBEX).
• Reader/Writer Mode
  RTD (Record Type Definition) with NDEF (NFC Data Exchange Format) and Tag Types 1–4.

Underlying RF layer: ISO 18092 with ISO 14443 Type A/B and FeliCa.

ZigBee

Low-power, low-data-rate wireless protocol by the ZigBee Alliance. Targets sensor networks and IoT applications.

• Power consumption
  Months to years of battery life.
• Max data rate
  250 Kbps.
• Low circuit complexity, low cost.

Protocol Stack

Built on IEEE 802.15.4 (physical and MAC layers for low-rate WPAN).

ZigBee adds three layers above 802.15.4:

• NWK (Network Layer)
  Routing, route discovery, route maintenance.
• APS (Application Support Sub-Layer)
  Service binding and message routing between application objects.
• APL (Application Layer)
  Application Objects and ZigBee Device Objects.

Device Types

Defined by IEEE 802.15.4:

• FFD (Full Functional Device)
  Operates as PAN coordinator, coordinator, or simple device. Communicates with FFD or RFD.
• RFD (Reduced Functional Device)
  Communicates only with a specific FFD. Suited for low-volume, simple applications.

Topologies

Star: a central PAN coordinator, with all devices connecting directly to it. Gives easy synchronization and low latency, but scales poorly.

Mesh / Peer-to-Peer: devices communicate directly with any in-range device. Gives robust multi-hop communication, multi-path routing, flexibility, and lower latency, at the cost of expensive route discovery and the need to store routing tables.

Cluster Tree: a hierarchical arrangement of coordinators and devices. Gives low routing cost, multi-hop reach, and scalability, but route reconstruction is costly, latency can be high, and the root node is a single point of failure.

Traffic Modes

Beacon Mode:

• Coordinator periodically broadcasts a beacon.
• Both coordinator and end device can sleep between beacons.
• Lowest energy consumption; requires precise timing.
• Beacon period ranges from milliseconds to minutes.

Non-Beacon Mode:

• Coordinator/routers must remain awake continuously.
• Supports heterogeneous networks with asymmetric power requirements.

Route Discovery

Broadcast-based protocol:

1. Source broadcasts RREQ (Routing Request) packet.
2. Intermediate nodes generate routing table entries back to source.
3. Endpoint router responds with RREP (Routing Response) packet.
4. Source generates routing table entry to destination.

Route maintenance tracks failed deliveries to neighbors and initiates route repair at a threshold. On total connectivity loss: orphaning procedure followed by re-association.

Comparative Summary