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

[Hakon]

Hello,

receiver sensitivity for Cat-M1 is -108 dBm and -107 dBm for low band and mid band respectively. For Cat-NB1/Cat-NB2 it's -114 and -113 dBm. It makes sense that you'll still receive something when the RSRP is close to -100 dBm.

[Hoang]

Dear Hakon

I am using THING:91 with NB-IoT of Telia (Norway)  to measure the temperature, .., RSRP, and send the data to my webserver.

It will send 1 package in each hour. and its staying underground, and I got the data from my thingy:91 (RSRP) 

My problem: when the signal is bad (RSRP < -130 dBM), it stopped working and couldnt reconnect at kl.19.24. 

At kl.13.20 , it did NOT send any package (because of bad signal), then, it sent again 14.23. 

My statemachine: 

 My main: 

void main(void)
{
      
     
      env_sensors_init();
      env_sensors_start_polling();
      battery_monitor_init();
      printk("modem_configure\n");
      modem_configure();
  
      while(1){
                                     
             
              
                printk("-----------------------\n\r");
                sensor_data_read();
                ENCR_HTTP_POST();
                k_sleep(DELAYPOST); 
            
               
        
       
      }

}

Connecting: modem_configure(); 

Read the temperature,battery,.., RSRP: sensor_data_read()

encrypted and send  (HTTP_POST): ENCR_HTTP_POST

sleep: 1hr

When the THINGY:91 stays underground, the signal is so bad ( RSRP = -130 dBm), and the worst case, NO signal, then, it couldnt POST (HTTP _POST), it will return ERROR, and I tried to reconnect:

void ENCR_HTTP_POST (void){
//FPOST: postData
int err = snprintk_post(FPost,HTTP_HOST,HTTP_PORT);
            
            if(!err){
                
                printk("done http post \n\r");
            }
            else {
                printk("httppost is error \n\r");
                 goto reconnect; 
            }
         return ; 
reconnect: 
      printk("reconnect network .......\n\r");
      reconnect_nw();
      //modem_configure(); 
     
}

my reconnect_nw() (similar to modem_configure()) 

void reconnect_nw(void){
                
                int err;
		printk("ReConnecting to LTE network. ");
		printk("This may take several minutes.\n");
		//ui_led_set_pattern(UI_LTE_CONNECTING);

		err = lte_lc_init_and_connect();
		if (err) {
			printk("LTE link could not be established.\n");
                        error_handler(ERROR_LTE_LC, err);
			
		}

		printk("Connected to LTE network\n");
}

and, my snprintk_post(): ( I m using http post from : https://github.com/Rallare/fw-nrfconnect-nrf/blob/nrf9160_samples/samples/nrf9160/https_simple/src/main.c is it your? )

int snprintk_post (char *PostString, char *HTTP_HOST, int HTTP_PORT)
{
     
   int poststat = '0';
   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 ; 
         }
    

    
     //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);
     
     int num_bytes = send(client_fd, send_buf, send_data_len_post, 0);
    
     printk("send err: %d\n\r", num_bytes);
     
     
     printk("Close socket \n\r");
     err = close(client_fd);
     
     freeaddrinfo(res);
     printk("============================== DONE SENDING =============================================== \n\r");
    
     return 0; 
     
clean_up:
	freeaddrinfo(res);
	err = close(client_fd);
        
}

Could you plz help me. I dont know why, it stopped working. 

 I tested it many times before I put it underground ( try to put it in the freezer, ..., somewhere with bad signal), and it worked

Thanks so much 

MVH, 

Hoang Nguyen 

[Hoang]

Hi Hakon

Thanks for fast response, I spent  2times to write the question to you ( 1st after writing, the  https://devzone.nordicsemi.com/ downed, couldnt submit, must did it again) 

Hakon said:

So you tested this with the thingy in the freezer and it worked?

YES, it worked, and RSRP: 

Hakon said:

Was it any lower when it was underground?

I think so, RSRP underground is about  -130 dBm, it is lower than in the freezer. 

the signal is not stable, it will be up and down, sometime it can connect, sometime it can NOT. I think, 

I am trying to build: if the NW is bad, it will try to reconnect. 

Do you have any solution ?

Thanks so much 

MVH

Hoang 

[Hakon]

Have you considered using an external antenna? The thingy antenna is not very good.

[Hoang]

No, just use internal one

[Hoang]

if we want the external antenna, which one should we use? do you have any suggestion 

[Hoang]

Hi Hakon

I hope you will have time for me today. 

1. With the external antenna, which one is suitable for THINGY:91 ( NB-IoT Telia) 

2. Go back my problem

Hoang said:

My problem: when the signal is bad (RSRP < -130 dBM), it stopped working and couldnt reconnect at kl.19.24. 

At kl.13.20 , it did NOT send any package (because of bad signal), then, it sent again 14.23. 

when the signal is bad (lost) for a long time, it couldnt reconnect, and just hang there. Have you met this problem before?  

        1.  I tried to put the thingy91 in a metal-box ( simulated for bad signal)

        2.  it stopped sending because of bad signal, if:

                   2.1.  10mn, took thingy out, it reconnected automatically and resent the package

                   2.2.  3hrs, took thingy out, I didnt receive any data from my thingy - it could NOT reconnect and resend the data !!!

Does error_handler() work correct in this case? 

/**@brief nRF Cloud error handler. */
void error_handler(enum error_type err_type, int err_code)
{
	/*if (err_type == ERROR_CLOUD) {
		if (gps_control_is_enabled()) {
			printk("Reboot\n");
			sys_reboot(0);
		}
                */
#if defined(CONFIG_LTE_LINK_CONTROL)
		/* Turn off and shutdown modem */
		printk("LTE link disconnect\n");
		int err = lte_lc_power_off();
		if (err) {
			printk("lte_lc_power_off failed: %d\n", err);
		}
#endif
#if defined(CONFIG_BSD_LIBRARY)
		printk("Shutdown modem\n");
		bsdlib_shutdown();
#endif
	}

#if !defined(CONFIG_DEBUG) && defined(CONFIG_REBOOT)
	LOG_PANIC();
	sys_reboot(0);
#else
	switch (err_type) {
	case ERROR_CLOUD:
		/* Blinking all LEDs ON/OFF in pairs (1 and 4, 2 and 3)
		 * if there is an application error.
		 */
		ui_led_set_pattern(UI_LED_ERROR_CLOUD);
		printk("Error of type ERROR_CLOUD: %d\n", err_code);
	break;
	case ERROR_BSD_RECOVERABLE:
		/* Blinking all LEDs ON/OFF in pairs (1 and 3, 2 and 4)
		 * if there is a recoverable error.
		 */
		ui_led_set_pattern(UI_LED_ERROR_BSD_REC);
		printk("Error of type ERROR_BSD_RECOVERABLE: %d\n", err_code);
	break;
	case ERROR_BSD_IRRECOVERABLE:
		/* Blinking all LEDs ON/OFF if there is an
		 * irrecoverable error.
		 */
		ui_led_set_pattern(UI_LED_ERROR_BSD_IRREC);
		printk("Error of type ERROR_BSD_IRRECOVERABLE: %d\n", err_code);
	break;
	default:
		/* Blinking all LEDs ON/OFF in pairs (1 and 2, 3 and 4)
		 * undefined error.
		 */
		ui_led_set_pattern(UI_LED_ERROR_UNKNOWN);
		printk("Unknown error type: %d, code: %d\n",
			err_type, err_code);
	break;
	}

	while (true) {
		k_cpu_idle();
	}
#endif /* CONFIG_DEBUG */
}

3. About the power consumption of thingy91: have you ever measured the power consumption on thingy when the signal is bad ( RSRP = -130 dBm -- -110dBm). Do you have any document about this one

Thanks a lot

MVH

Hoang Nguyen

[Hakon]

Hoang said:

1. With the external antenna, which one is suitable for THINGY:91 ( NB-IoT Telia) 

 Which frequency bands are you going to use? The ideal antenna will depend on the frequencies.

[Hoang]

Hakon said:

Which frequency bands are you going to use? The ideal antenna will depend on the frequencie

1. Telia NB IoT (800 MHz): 801-811 downlink 842-852 uplink

2. Telia NB IoT (1800 MHz): 1745-1765 downlink 1840-1860 uplink

[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