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UNIQUE SEQUENCE FREQUENCY HOPPING FOR INTERNET OF THINGS

IP.com Disclosure Number: IPCOM000249795D
Publication Date: 2017-Apr-05
Document File: 4 page(s) / 172K

Publishing Venue

The IP.com Prior Art Database

Related People

Huimin She: AUTHOR [+4]

Abstract

Unique frequency hopping sequences are generated in communication networks (e.g., Internet of Things networks) in compliance with Federal Communications Commission (FCC) rules (e.g., FCC-Part-15.247). These unique frequency hopping sequences may reduce the probability of interference, efficiently use the full frequency band, and include pseudo-random sequences.

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Copyright 2017 Cisco Systems, Inc. 1

UNIQUE SEQUENCE FREQUENCY HOPPING FOR INTERNET OF THINGS

AUTHORS: Huimin She

Yuzhuo Yang Chuanwei Li Jason Chen

CISCO SYSTEMS, INC.

ABSTRACT

Unique frequency hopping sequences are generated in communication networks

(e.g., Internet of Things networks) in compliance with Federal Communications

Commission (FCC) rules (e.g., FCC-Part-15.247). These unique frequency hopping

sequences may reduce the probability of interference, efficiently use the full frequency

band, and include pseudo-random sequences.

DETAILED DESCRIPTION

Frequency hopping, also known as frequency hopping spread spectrum (FHSS), is

a method of transmitting radio signals by rapidly switching a carrier among multiple

channels using a pseudo-random sequence known to both transmitter and receiver.

Frequency-hopped transmissions have advantages over fixed frequency transmissions,

including being resistant to interference and difficult to intercept. As such, frequency-

hopped transmissions are widely used in many applications, such as the Internet of Things

and Smart Utility Networks.

In frequency hopping networks, before a node can communicate with a peer node,

the node first needs to know the channel hopping sequence of the peer node. The

transmitter-receiver pair need to be on the same channel during the transmission. Moreover,

according to Federal Communications Commission (FCC) rules (FCC-Part-15.247), the

frequency hopping mechanism must use all available channels equally on average in a

pseudo-random sequence. Therefore, one of the main challenges of frequency hopped

transmissions is computing the pseudo-random hopping sequence.

As described herein, a mechanism generates a unique frequency hopping sequence

in compliance with FCC rules. This mechanism reduces interference probability and

Copyright 2017 Cisco Systems, Inc. 2

improves band utilization to efficiently use the full frequency band. The unique frequency

hopping sequence may be a pseudo-random sequence.

Certain terms as used herein are defined as follows:

- Channel table: Contains a list of channels that are available for usage. Users may

configure the channel table to exclude specific channels when interference over those

channels is expected.

- Channel hopping sequence: A list of channels that a node follows when listening for

transmissions.

- Hopping period: The length of the frequency hopping sequence.

- Time slot: Time is divided into slots. At the beginning of a slot, the node switches to

the next channel in the frequency hopping sequence for listening. The hopping period

is divided into equally sized time slots.

For simplicity, it is assumed that there are N channels available for usage. The

hopping sequence includes N slots numbered from 0 to N-1. Per the above definition, the

hopping period equals the length of the hopping sequence for N slots.

Example steps for computing the frequency hopping sequence are described as

follows.

Step 1: Shuffle the Channel Table

The original...