AssistNow getting started

Introduction

AssistNow is u-blox’s end-to-end A-GNSS location service that provides data in real time via AssistNow Online, as well as predicted data via AssistNow Offline, and the two can either be used alone or in combination. AssistNow boosts GNSS acquisition performance and lowers power consumption for devices with or without network connectivity.

AssistNow Online

AssistNow Online provides satellite ephemerides, health information and time aiding data suitable for GNSS receiver systems with direct internet access.


AssistNow Offline


The AssistNow Offline service benefits u-blox GNSS receivers that only have occasional internet access. The receiver will download the AssistNow data when the receiver has an Internet connection and use the AssistNow data later to achieve fast TTFF.

In this getting started guide, we will explain how to access the AssistNow service using the Thingstream platform and get assistance data for your end application.

Pre-requisites


In order to access either service, you need to sign-up on the u-blox Thingstream delivery platform and generate a token as explained in the following sections.

u-blox Service Platform Sign-up

u-blox Thingstream is a service delivery platform providing a management console that you can use to enable and manage the entire suite of u-blox services , including IoT Location-as-a-Service and your AssistNow service tokens.

Sign-up is free, quick and easy. Just go to the management console and register with your company information. If you already have a Thingstream domain for IoT Communication-as-a-Service (MQTT Anywhere, MQTT Here or MQTT Now), or for IoT Security-as-a-Service you do not need to register again.

Service Configuration

Once you have signed up on the Thingstream platform, it's time to generate the access token to use either of the AssistNow services. The token is one of the key parameters supported in the HTTPS protocol between the u-blox AssistNow Server, and the AssistNow Client requesting information.

Generate AssistNow Online Token

Select Location Services from the side bar of the Thingstream console and click on Add Location Thing in the top right of the screen.

Then click on the "Generate Tokens" under the Cell Locate / AssistNow Tokens section.

Choose the "AssistNow Online" service from the Select Services section and give your token a name.

Next, you'll need to select a pricing plan to link to it. You can find more information about the AssistNow service plans on our pricing page .

Once you have generated a token, you could find the token information like associated service, token string, status, plan, etc. in the "Details" tab of that token.

Generate AssistNow Offline Token

Similarly, to access the AssistNow Offline service, you would also need to generate an AssistNow Offline token . You could either add the "AssistNow Offline" service to the same token or generate a new token. To add another service to an existing token already generated for one of the services, you would need to click on Add Services in the "Associated Tokens" section in the Details tab of your existing token.

Choose "AssistNow Offline" and a select a pricing plan to link with it.

If you want to generate a new token for AssistNow offline, you could follow the instructions in Generate AssistNow Online Token section, just choose "AssistNow Offline" while selecting services instead of AssistNow Online. Please check out more information on token generation and management here.

Service Usage

The information exchange with the AssistNow Online Service is based on the HTTPS protocol. Upon reception of an HTTPS GET request, the server will respond with the required messages in binary format or with an error string in text format. The request from the client to the server should contain a standard HTTPS query string in the request URL. The query string consists of a set of "key=value" parameters as demonstrated in the next sections.

Request URL - AssistNow Online

You can request the assistance data from the service using the token that you have generated. All you need to do is to copy the token string from the thingstream portal and paste it as a value for the token parameter (highlighted in red as seen in the example URL below ). For example, your application can request the ephemeris, almanac and auxiliary data for both GPS and GLONASS from the AssistNow Online servers as follows:


Example URL:

https://online-live1.services.u-blox.com/GetOnlineData.ashx?token=XXXXXXXXXXXXXXXXXXXXX;gnss=gps,glo;datatype=eph,alm,aux;


Let's say the authorized token string that you generated in the thingstream portal is
58XXXXXXXXXXXXXXXXXXYQ , so the request URL would accordingly be:

https://online-live1.services.u-blox.com/GetOnlineData.ashx?token=58XXXXXXXXXXXXXXXXXXYQ;gnss=gps,glo;datatype=eph,alm,aux;

The details of all the supported request parameters for the AssistNow Online could be read
here.


The data returned by the AssistNow Online Service is a sequence of UBX-MGA messages, starting with an estimate of the current time in the form of a UBX-MGA-INI-TIME_UTC message.

To try out the service, you can simply copy the request URL with a valid token and paste it in your internet browser. The server will return you with a "mgaonline.ubx" file.

There are two AssistNow Online endpoints available, providing redundancy in the event of server unavailability. The two endpoints are as below:

· online-live1.services.u-blox.com

· online-live2.services.u-blox.com


Users may obtain data from either address. A strategy involving trying the other address in case of failure provides greater system reliability.

Request URL - AssistNow Offline


Once you have the token generated for AssistNow Offline service, you could
request for GPS aiding data for a period of 1 week with resolution = 1 day (a valid token should be provided for the token parameter) using the following URL:

Example URL:


https://offline-live1.services.u-blox.com/GetOfflineData.ashx?token=XXXXXXXXXXXXXXXXXXXXX;gnss=gps;period=1;resolution=1


The details of the supported request parameters for the AssistNow Offline could be read here.


The downloaded Offline data is encoded in a sequence of UBX-MGA-ANO messages, one for every SV for every day of the period covered.

To try out the service, you can simply copy the request URL with a valid token and paste it in your internet browser, the server will return you with a "mgaoffline.ubx" file.

Like the Online service, there are also two endpoints available for Offline service that provide for redundancy:

· offline-live1.services.u-blox.com

· offline-live2.services.u-blox.com

In a real application scenario, the messages package in the form of .ubx files would be received by the host application or the u-blox cellular module and passed on to the GNSS receiver. For more details on the technical implementation of the AssistNow Online and Offline services, please check out the reference documentation below.