RSSI and RSRP on THINGY.91

[Hoang]

Dear, 

Im trying to measure the RSSI with THINGY:91, I found on the document  nrf91_at_commands_v1.1.pdf about

1. AT+CSQ

      +CSQ: <rssi>,<ber>

Note: Not detectable, RAT not supported. Use +CESQ and %CESQ for E-UTRA signal quality.

2. AT + CESQ 

    +CESQ: <rxlev>,<ber>,<rscp>,<ecno>,<rsrq>,<rsrp>

<rsrp>
0 – RSRP < −140 dBm
1 – When −140 dBm ≤ RSRP < −139 dBm
2 – When −139 dBm ≤ RSRP < −138 dBm
...
95 – When −46 dBm ≤ RSRP < −45 dBm
96 – When −45 dBm ≤ RSRP < −44 dBm
97 – When −44 dBm ≤ RSRP
255 – Not known or not detectable

I am using AT+CESQ to find RSRP 

and, i found some document about RSRP range: 

https://wiki.teltonika.lt/view/RSRP_and_RSRQ

But, when I tested to measure it, i got: 

I set the devices (3) in my freezer, and got the RSRP < -100dBm, 

is it conflict here? On the document, they say: NO signal when RSRP < -100dBm, but, I measured -120dBm, and I still received the data from my THINGY:91 - it means : still signal 

I am using Telia NB-IOT( Unit1) Telia LTE-M(Unit2) and Telenor LTE-M(Unit3)

My question is: RSRP vs Signal strength range? RSRP for no signal?

Thanks 

BR, 

Hoang Nguyen

[Hoang]

Hi Hakon, 

I may find a problem with my thingy91.

In my HTTP POST: 

detail of my HTTP_POST: 

int snprintk_post (char *PostString, char *HTTP_HOST, int HTTP_PORT)
{
     
  
   struct sockaddr_in local_addr;
   struct addrinfo *res;
   printk("Webserver: http://%s:%d \n\r",HTTP_HOST,HTTP_PORT); 

   local_addr.sin_family = AF_INET;
   local_addr.sin_port = htons(0);
   local_addr.sin_addr.s_addr = 0;
 
    int err = getaddrinfo(HTTP_HOST, NULL, NULL, &res);
    printk("get addrinfo\n\r");
    printk("getaddrinfo err: %d\n\r", err);
    
    if(!err) {
       printk("network is OK: \n\r");
    }

    else {
         printk("network is error: \n\r");
         return CONFIG_LTE_ERR ; 
    }
    
    ((struct sockaddr_in *)res->ai_addr)->sin_port = htons(HTTP_PORT);
    
   
    char send_buf[MAXLINE + 1];
    int send_data_len_post  = snprintk(send_buf,
				         500, 
				         POST_TEMPLATE, HTTP_PATH,
				         HTTP_HOST, strlen(PostString),
				         PostString);

     printf("send_buf is: %s \n",send_buf);
     printk("send_data_len_post: %d\n\r", send_data_len_post);
     
     int client_fd = socket(AF_INET, SOCK_STREAM, 0);

     printk("client_fd: %d\n\r", client_fd);
     err = bind(client_fd, (struct sockaddr *)&local_addr, sizeof(local_addr));
     printk("bind err: %d\n\r", err);
     if(!err )
        {
          printk("bindnetwork is OK \n\r");
          
         }
     else
        {
          printk("network is error: \n\r");
          return CONFIG_LTE_ERR ; 
         }
    

     //hng: 17012020 testing bad signal

     //err = blocking_connect(client_fd, (struct sockaddr *)res->ai_addr,sizeof(struct sockaddr_in));

      err = connect(client_fd, (struct sockaddr *)res->ai_addr, sizeof(struct sockaddr_in));
	if (err > 0) {
		printk("connect err: %d\n", errno);
		goto clean_up;
	}
     //err = blocking_connect(client_fd, (struct sockaddr *)res->ai_addr,sizeof(struct sockaddr_in));
     printk("connect err: %d\n\r", err);
     /*
     if(!err )
        {
          printk("blocking_connectnetwork is OK: \n\r");
          
         }
     else
      {
           printk("network is error: \n\r");
           return CONFIG_LTE_ERR ; 
      }
      */
     int num_bytes = send(client_fd, send_buf, send_data_len_post, 0);
    
     printk("num_bytes sent: %d\n\r", num_bytes);
     
     //get the fb from webserver ; 
     /*
     int tot_num_bytes = 0;
     do {
		
         num_bytes =blocking_recv(client_fd, recv_buf, RECV_BUF_SIZE, 0);
         tot_num_bytes += num_bytes;
         if (num_bytes <= 0) {
			break;
		             }
	// printk("%s \n\r", recv_buf);
	} while (num_bytes > 0);
     */
     printk("Close socket \n\r");
     err = close(client_fd);
     
     freeaddrinfo(res);
     printk("============================== DONE SENDING =============================================== \n\r");
     //poststat = true; 
     return 0; 
     
clean_up:
	freeaddrinfo(res);
	err = close(client_fd);
        
}

If the bad signal  came  ( < -135 dBm) when http_posting, it may return HTTP_ERR

( 

connect(client_fd, (struct sockaddr *)res->ai_addr, sizeof(struct sockaddr_in));

i used to get the error from this step)

then, I tried to reconnect_nw():   lte_lc_init_and_connect()

And, I may  get the ERROR:

Exception occurred in Secure State
***** HARD FAULT *****
  Fault escalation (see below)
***** BUS FAULT *****
  Precise data bus error
  BFAR Address: 0x50008120
***** Hardware exception *****
Current thread ID = 0x2002abec
Faulting instruction address = 0x74b056ee
Fatal fault in ISR! Spinning...

The problem: The network haven't disconnected yet !!! HTTP_POST returned the ERROR, but I dont know exactly why, and what kind of error?

If I tried:  DISconnect before reconnect_nw(), I wont get any ERROR.  

What kind of error can we meet in HTTP POST? 

( I m sure, my webserver is OK)

COuld you help me, I want to know about what kind of error can we meet in http post, and the solution for each of them?

Thanks so much

MVH

Hoang Nguyen

[Hakon]

Hoang said:

What kind of error can we meet in HTTP POST? 

I'm not sure what you're referring to. Is this "HTTP POST" something in the SDK or something you have written?

[Hoang]

I got it from:  https://github.com/Rallare/fw-nrfconnect-nrf/blob/nrf9160_samples/samples/nrf9160/https_simple/src/main.c

Its not my, so Im confusing about the errors can be returned from httppost

[Hakon]

I might be blind or something, but I really can't find the "http_post" you're referring to. It's not in main.c as far as I can tell.

Also, I see that there is a ENCR_HTTP_POST() in the diagram you posted. Is that it? Where can I find this?

[Hoang]

Dear Hakon

My fall, I used app_http_start() from: https://github.com/Rallare/fw-nrfconnect-nrf/blob/nrf9160_samples/samples/nrf9160/https_simple/src/main.c to write: snprintk_post() 

And,  ENCR_HTTP_POST(), I encrypted my data before posting: snprintk_post()

//char DPost[500]; //encryptedData will be posted to webserver: HTTP_HOST:HTTP_PORT

int err = snprintk_post(DPost,HTTP_HOST,HTTP_PORT);