Apparatus and method for antenna switching on a radio transceiver

Abstract

The invention relates to a method and a device (St) for controlling an antenna switching (U) of a radio transceiver (TR) having at least two antennas (A1, A2), wherein the device is designed (St) to switch (U) a transmission in the form of a transmission and / or reception of a signal (Sig) by a first antenna (A1) of the radio transceiver (TR) to a transmission of the signal (Sig) by another antenna (A2) of the radio transceiver (TR), wherein an antenna switching decision interval (I1) is determined, after which, taking into account (ENZ) a negative count (NZ, 'water level count') of at least a preceding consecutive negative switching decision (NU), a decision is provided at an antenna switching decision time (T) as to switching (U) between the antennas (A1, A2), respectively.

Description

Technical Field

[0001] This patent application relates to an apparatus and method for antenna switching in the case of a radio transceiver, particularly a Bluetooth radio transceiver. Summary of the Invention

[0002] The purpose of this invention is to improve antenna switching in radio transceivers, particularly in the case of Bluetooth radio transceivers. This purpose is achieved through the invention itself.

[0003] Using negative counts ('water level_count') and negative count limits ('water level_threshold') of previous switches that did not occur in decisions about antenna switching can have the following advantages: – If a predefined number of consecutive unsuccessful antenna handover decision events are reached, force an antenna handover. – In the event of an active / imminent radio event, antenna switching can be optionally avoided.

[0004] According to one embodiment of the invention, a positive count ('successful handover_count') and a positive count limit value ('successful handover_threshold') can also be considered. One possible advantage is... – Stop antenna switching if a predefined number of consecutive successful antenna switching decision events are reached. Attached Figure Description

[0005] Further features and advantages of some embodiments of the present invention will become apparent from the following description of exemplary embodiments with reference to the accompanying drawings, in which: Figure 1 A flowchart of the antenna switching decision is shown, which also considers the number of previous consecutive positive switching decisions and the number of previous consecutive negative switching decisions. Figure 2 The diagram shows the transceiver's scan / passive state, the antenna signal reception phase below, and the time curve of the antenna switching interval below. Figure 3 The phases of the scan event and the antenna switching decision event are shown. Figure 4 This illustrates the potential synchronization effects when using the SW timer (which always has a higher time priority than a separately configured timer task for antenna switching). Figure 5 This shows that an antenna switch is rejected once every four antenna switch decision events. Figure 6 A motor vehicle with a controller is shown, which is used to control a Bluetooth transceiver, specifically for switching between at least two antennas based on two counts and two limit values. Figure 7 Another flowchart for antenna switching decisions is shown, which also provides the maximum latency for checking radio events. Figure 8 Another flowchart of the antenna switching decision is shown, in which the maximum waiting time until the end of the radio event is reached. Detailed Implementation

[0006] Figure 6 An example of an embodiment of the present invention is shown, comprising a motor vehicle 1 and a mobile terminal 2 (e.g., a cellular phone, a key, etc.). Each of the (1; 2) has a controller St for controlling (more particularly, Bluetooth) transceivers TR, the controller being configured to: switch U between two (or alternatively more than two) antennas A1, A2 based on two counts (positive count PZ's success count and negative count NZ's level count) and two limit values ​​(positive count limit value (PZG, 'success count' and negative count limit value (NZG, 'level threshold')); avoid antenna switching U in the event of activation of the transmit / receive signal Sig and / or an impending radio (transmit / receive) event; and force antenna switching U in the event of a predefined number of consecutive negative (= no switching U) antenna switching decision events (at antenna switching decision time T, respectively, measured by timer Ti), and stop antenna switching U in the event of a predefined number of consecutive positive (= switching U) antenna switching decision events (at antenna switching decision time T, respectively). Background technology: For various reasons, modern radio transmission technologies typically operate in frequency bands above 1 GHz, for example, 2.4 GHz – 2400 to 2480 MHz in the case of ISM. Therefore, wavelengths of a few centimeters exist (approximately 12.5 cm in the case of 2.4 GHz).

[0008] Inside buildings (office buildings, underground parking garages) and vehicles, transmitted signals can be reflected multiple times under certain circumstances, such as by reflections on walls and ceilings. At the receiving antenna, a signal will appear, composed of signals from different propagation paths that are superimposed in phase according to their respective path losses, phase shifts, and antenna characteristics (polarization, directional characteristics).

[0009] The superposition of phases produces both constructive and destructive superposition; therefore, the reception level is greatly affected. This is known as a multipath propagation situation with so-called fading.

[0010] For different frequencies and antenna orientations, multipath propagation typically changes relatively quickly, and statistically independent (unrelated) reception levels may appear.

[0011] Compared to using different frequencies (channels), transmission standards rarely explicitly specify the use of different antennas.

[0012] However, from a physics perspective, using different antennas is just as desirable as using different frequencies. Furthermore, from the perspective of communication control (link layer) of transmission standards, there is no difference between signal transmission errors caused by an "incorrect" frequency or an "incorrect" antenna. Therefore, antenna switching can adapt relatively well to the provided communication sequence.

[0013] This application discloses a method for enabling antenna switching U within the range of possibilities of commercially available integrated circuits for BLE communication.

[0014] The link layer (LL) level of the transmission standard organizes the communication sequences of data packets exchanged at the physical layer (PHY) level with strict time requirements.

[0015] LL communication sequences are typically designed to be fault-tolerant. Not every communication attempt must succeed; therefore, repeated attempts are made directly. Thus, communication attempts might sometimes be made on antennas A1 and A2, but these antennas might not actually be within range until later. This creates antenna diversity, but at the cost of response time.

[0016] This application defines the parameters of the link layer and issues commands from higher levels related to the operational status of the link layer to be processed. The timing of transmit and receive actions at the PHY level is unknown to the application.

[0017] LL control is not directly accessible to the IC user. It is typically implemented through a separate software component of the IC, or even hardwired.

[0018] LL control takes into account the HW conditions of the IC, and its behavior must conform to the specifications of the communication standard (e.g., Bluetooth 5.2), meaning it is usually certified.

[0019] Therefore, antenna switching in the user section cannot be directly integrated into the link layer; it must be implemented at the application switch level.

[0020] One aspect of the method according to the invention is to implement antenna switching in the application software of the transceiver IC. However, the method can also be directly integrated into the LL, which would be relatively simple and efficient.

[0021] The following examples illustrate communication according to the Bluetooth Low Energy (BLE) communication standard.

[0022] The necessary operational states for BLE LL are "Advertisement", "Initiate / Scan", and "Connect".

[0023] Transmitting and receiving actions may need to be performed periodically depending on the corresponding status.

[0024] Modern ICs can implement the above states quasi-simultaneously. For example, an IC can establish up to eight connections with different remote sites and can also perform "advertising" and "initiation / scanning". In this case, the IC's link layer control can perform necessary time-division multiplexing between different state sequences or transmit and receive actions based on the IC's given hardware resources.

[0025] Antenna switching U is designed to be integrated with the corresponding transmit and receive actions within these state sequences.

[0026] In addition to the fault-tolerant communication sequences for the use of different antennas in LL, a particularly important point here is the possibility of implementing quasi-simultaneous processing of different operating states.

[0027] In theory, antenna switching can be directly integrated into the LL (Limited Linear Control). Then, it's possible to actively control which antenna will perform the upcoming transmit or receive action, taking into account operational status or connectivity dependencies. However, this approach would imply significant management complexity.

[0028] In the case where LL is inaccessible, antenna switching initiated by timer Ti can be envisioned. In this case, the antenna can undergo a large-scale change, for example, every 100 ms, independent of the current operating state.

[0029] Furthermore, it is conceivable that antennas A1 and A2 will not be changed when the transmission or reception action has just occurred or is about to occur.

[0030] From the user's perspective, a delay will occur if communication is impossible on antennas A1 and A2. Furthermore, the BLE connection is considered terminated (Supervisory Timeout, SVTO) after a specific period when communication is no longer possible.

[0031] This behavior is problematic in the "Initiate / Scan" operation state. To minimize power consumption, scan events should only occur occasionally, but they should alternate on the antenna to minimize response time.

[0032] Given that the antenna changes every 100 ms (e.g., to avoid SVTO on “incorrect” antennas A1, A2 in a possible connection), a scan event lasting 100 ms is performed only once every 1000 ms, for example.

[0033] In addition, it should be noted that in order to obtain a deterministic response time, it is usually necessary to keep the same antenna A1 or A2, etc., on the entire scanning window.

[0034] As long as the IC only performs "initiate / scan", antenna switching can be achieved based on messages going to the application SW layer.

[0035] However, if multiple operational states must be processed quasi-simultaneously (parallel processing of advertisements or different connections), the solution will gradually become unusable due to the number of messages to be considered.

[0036] This patent application achieves these requirements in a simple manner.

[0037] Starting with antenna switching based on timer Ti and according to an embodiment of the invention, the present invention aims to realize antenna switching U, which further considers the number of possible switching times (i.e., at the antenna switching decision time T) of consecutive successful (switching in the form of decision PU) and failed (not switching in the form of decision NU) switching, respectively (positive count PZ's switching success count' and negative count NZ's water level count'). Figure 1 As shown in the flowchart.

[0038] The antenna switching interval I1 is defined using a timer Ti. Based on this periodicity, negative NU (i.e., no switching) and positive PU (i.e., switching) antenna switching decisions (also known as antenna switching decision events) are executed periodically at the antenna switching decision time T.

[0039] At the antenna switching decision time T, in each case (where the number of final consecutive positive switching decisions PU is less than the limit value PZG). First, check (ESIG1, ESIG2) to confirm whether the radio event RE (in the form of an ongoing or planned signal Sig transmission and / or reception) in the link layer (=LL) section is executed (ESIG1+) or planned to occur soon (ESIG2+), or is not executed (ESIG1-) and not planned to occur soon (ESIG2-).

[0040] If neither of these two cases (ESIG1- and ESIG2-) is found, a positive switching decision PU can be executed and a switching U can be executed; otherwise (if the negative count NZ = 'water level_count' of the previous consecutive negative switching decisions NU is less than the negative count limit NZG 'water level_threshold'), a negative switching decision NU can be executed but a switching U can be not executed.

[0041] In addition, a limited waiting time WT can be envisioned, which involves first attempting to wait (W) until the activation or imminent radio event phase RE ends.

[0042] exist Figure 7 The exemplary embodiment illustrates this (optionally possible) waiting time WT by way of example. The duration of the wait is the maximum possible predefined waiting time WT, provided that a radio event RE is executed or planned to occur shortly thereafter (ESIG1+ and ESIG2+). As long as the executed or planned radio event phase RE ends during this waiting time WT (i.e., ESIG1- and ESIG2- occur), a positive handover decision PU can be executed and a handover U can be performed. The process continues to ENZ as long as the execution or planning of the radio event RE continues until the end of the waiting time WT (while ESIG1+ and ESIG2+ still apply).

[0043] As long as the link layer (=LL) has to handle many radio events RE, the following may happen: relatively speaking, antenna U is usually not switched (for positive switching decision PU, so it is also not switched) (NZ>NZG.

[0044] Using the negative count NZ = 'water level_count' of the previous consecutive negative handover decisions NU, after the number of negative antenna handover decisions NZ (= the decision that does not need to be performed at antenna handover decision time T) corresponding to the negative count limit value NZG 'water level_threshold' (NZ>= NZG), the REA is terminated or the activated or imminent radio event RE (i.e., the transmission or reception of signal Sig via antenna A1 or A2) is prevented, and the positive handover decision PU forces the antenna handover U (from the first antenna A1 to the other antenna A2).

[0045] like Figure 8 As demonstrated, a limited waiting time WTRE can be envisioned before actually terminating or preventing a potential radio event phase. Therefore, one can attempt to wait for the radio event phase RE to end. As long as the phase successfully ends, it is not necessary to terminate or prevent the active or impending radio event RE. If the radio event RE is still active or impending after the waiting time WTRE has elapsed, then these radio events must be terminated or prevented as described above.

[0046] The attached figure's reference numeral FAS indicates a forced handover via the termination of the transmission process by REA and the positive decision PU supporting the handover U.

[0047] In the case of a forced FAS switch, the blocking of all active, impending, or potentially new radio events (REs) should continue at least until the end of the antenna switch U to ensure that the antenna switch U is not interfered with.

[0048] It is also conceivable to prevent, for example, unexpected (in the short term) new radio events during the duration of the non-mandatory antenna switching U, and to further ensure that the antenna switching U process is not interfered with.

[0049] After the positive handover decision PU supports antenna switching U (from the first antenna A1 to another antenna A2), The positive count PZ increments by one (PZ := PZ + 1), and The negative count NZ is set to zero (reset).

[0050] After the negative switching decision NU against antenna switching U (from the first antenna A1 to another antenna A2), The negative counter NZ is incremented by one (NZ := NZ + 1), and The positive count PZ is set to zero (reset).

[0051] The purpose of this process is that, in a typical case with only one active BLE (Bluetooth Low Energy) connection, antenna switching U is almost always performed and few or no radio events RE are disrupted (i.e., terminated or blocked) by antenna switching U. As the utilized IC capacity increases, switching U is forced; in this case, the situation where radio events disrupt (terminate) REA is accepted, but if antenna A1 or A2 is out of range, termination of the BLE connection is blocked (via SVTO), and minimum system response time and antenna diversity effect are ensured.

[0052] The number of consecutive successful antenna handover events (i.e., handover U) is counted using the positive count PZ's "successful handover count".

[0053] When the predefined positive count limit value PZG's successful switching threshold' is reached, the antenna switching U is actively stopped (for one or more subsequent antenna switching events) (EPZ: PZ>PZG).

[0054] Furthermore, the size of the antenna switching interval I1 is defined by the scanning interval I2 between the two scanning windows SW (scanning is performed during each scanning window, e.g., to obtain possible connections). As long as the scanning interval I2 is an even multiple of the antenna switching interval I1, relevant parameters will be generated. Figure 2 The relationship between the operation status "initiated / scanned" is given, for example, when n = 4, where... Figure 2 The transceiver TR status RXSt (receiving RX in the scan window) is shown above, and the received signal RE via antenna A1 or A2 is shown below: In the above example, four antenna switching decision events (i.e., decisions to favor (PU) or oppose (NU) switching U) occur at each scanning interval I2. Since the radio event RE activated right at its start (in the case of NZ<NZG) prevents the antenna switching U from being performed, successive scanning events in the scanning window SW are processed directly on different antennas A1, A2.

[0055] The phase of the antenna switching decision events does not need to be synchronized with the phase of the scanning events. A special case occurs at zero phase, where the start of the scanning window SW coincides with the moment of the antenna switching event, as shown Figure 3 indicated by the left arrow P1 in the figure.

[0056] However, since the antenna switching decision events are located at least outside said window, either towards the end of the scanning window SW or towards the start of the scanning window SW, the antenna switching U is performed at one of these two moments, and accordingly, successive scanning events SW also occur on different antennas A1, A2 during zero phase (P2).

[0057] Depending on the phase difference between the scanning time and the antenna switching time, successive scanning events SW are sometimes performed on the same antenna A1 or A2. This is tolerable within the achievable accuracy range of the timer Ti, or limits the average tolerable error of the timer Ti for antenna switching U.

[0058] The use of so-called SW timers, which are allocated time slices for the CPU of, for example, a real-time operation (ROC) system, can be problematic. In this case, the time priority for performing scanning SW can be higher than the time priority of the additionally configured timer task for performing antenna switching U.

[0059] This priority order produces a synchronization effect, as a result of which antenna switching is performed both at the start and at the end of the scanning window SW near zero phase P2, as Figure 4 shown in the figure.

[0060] This results in a fairly long period of time in which the scanning event SW is performed only on one antenna A1 or A2 in some cases. Only over a 'very' long period of time (at 'very' many antenna switching moments) is the average error of the SW timer not affected by this ROC effect.

[0061] To avoid this behavior in antenna handover U, the number of consecutive successful antenna handover events (in the form of positive handover decisions, i.e., handover U) is counted using the positive count PZ's success count of previous consecutive positive handover decisions PU. If this number exceeds a predefined positive count limit (threshold) PZG ='successful handover threshold', antenna handover U is intentionally prevented (by an immediate negative handover decision NU, i.e., no handover).

[0062] In this example, a failed antenna handover NU typically occurs once every four antenna handover events; this is forced by the positive count PZ's success count, such as... Figure 5 As indicated by the arrow in the image: Therefore, despite the synchronization effect, the continuous scan interval SW still occurs on different antennas A1 or A2. Furthermore, the "successful handover method" allows the selected scan window time to be shorter than the antenna handover interval I1, thus enabling additional degrees of freedom at the system level.

[0063] List of reference numerals 1. Motor vehicles 2 Mobile terminals ST control U switch A1 antenna A2 antenna Sig signal RE Radio event, transmitting or receiving signal Sig via antenna A1 or A2. REA terminates or blocks radio events TR transceiver Ti timer t time T antenna switching decision time I1 Antenna switching decision periodic interval The scan interval for the I2 radio transceiver TR to perform periodic scans. EPZ Decision / Considering Positive Counts PZ PZ = 'Switch Success Count', the positive count of previous consecutive positive switch decision PUs. PZG = 'Switch Successful_Threshold', a predefined positive count limit value. PZ>= PZG Positive count PZ'Switch Success_Count', equal to or higher than the predefined positive count limit value PZG'Switch Success_Threshold' PU is switching decisions NU negative switching decision NZ'water level_count', the negative count of previous consecutive negative switching decisions NU The negative count limit (i.e., 'water level threshold') of the NZG negative antenna switching decision NU. ENZ Decision / Consider the negative count of the previous consecutive negative switching decision NU (NZ, 'water level_count') PZ <pzg 正计数pz‘切换成功_计数’，低于预定义的正计数极限值pzg‘切换成功_阈值’ESIG1+ No transmission or reception of signal Sig was performed. ESIG2+ does not plan the transmission or reception of signal Sig within a predefined time. ESIG1 - Transmission or reception of the execution signal Sig ESIG2 - Scheduled transmission or reception of signal Sig within a predefined timeframe. SW Scan Window< / pzg>

Claims

1. A method for controlling antenna switching (U) of a radio transceiver (TR) having at least two antennas (A1, A2), This method is used to switch (U) the transmission (of a signal) in the form of transmission and / or reception via the first antenna (A1) of the radio transceiver (TR) to the transmission of a signal (Sig) via another antenna (A2) of the radio transceiver (TR). in, Considering the negative count (NZ) of previous consecutive negative handover decisions (NU) and the positive count (PZ) of previous consecutive positive handover decisions (PU), a decision regarding handover (U) between these antennas (A1, A2) is made at the antenna handover decision time (T), where a negative handover decision is a no-handover decision and the negative count is the no-handover count, and a positive handover decision is a handover decision and the positive count is the handover count. The feature is that if the positive count (PZ) is lower than a predefined positive count limit (PZG), and if, at the antenna switching decision time (T), the transmission or reception of the signal (Sig) is performed or planned within a predefined time, And if the negative count (NZ) is equal to or higher than the predefined negative count limit (NZG). It then provides a positive handover decision (PU) in the form of a handover (U).

2. The method as described in claim 1, If the positive count (PZ) is lower than the predefined positive count limit (PZG), then... Furthermore, if, at the antenna switching decision time (T), the transmission or reception of a signal (Sig) is not performed or planned within a predefined time, It then provides a positive handover decision (PU) in the form of a handover (U).

3. The method as described in any one of claims 1 to 2, The positive switching decision (PU) mentioned therein includes the termination or blocking of the transmission.

4. The method as described in any one of claims 1 to 2, The maximum allowed waiting time (WT) is until the transmission or reception of the signal (Sig) is no longer performed or planned.

5. The method as described in any one of claims 1 to 2, If the positive count (PZ) is lower than the predefined positive count limit (PZG), then... Furthermore, if at the antenna switching decision time (T), the transmission or reception of the signal (Sig) is performed or planned within a predefined time, And if the negative count (NZ) is below the predefined negative count limit (NZG). Then a negative handover decision (NU) is provided, which takes the form of no handover (U).

6. The method as described in any one of claims 1 to 2, Where the positive count (PZ) is equal to or higher than the predefined positive count limit (PZG). Then a negative handover decision (NU) is provided, which takes the form of no handover (U).

7. The method as described in any one of claims 1 to 2, If a negative switching decision (NU) is executed in the form of no switching (U), then at least an adjustment to the negative count (NZ) is also provided.

8. The method as described in any one of claims 1 to 2, If a positive switching decision (PU) in the form of a switch (U) is executed, then at least the positive count (PZ) is adjusted.

9. The method as described in any one of claims 1 to 2, in, If adjustment for the negative count (NZ) is provided, then adjustment for the positive count (PZ) is also provided, and / or If an adjustment for the positive count (PZ) is provided, an adjustment for the negative count (NZ) is also provided.

10. The method as described in any one of claims 1 to 2, Its features are, The duration of the scan interval (I2) during which the radio transceiver (TR) performs periodic scans is defined as an even multiple (n) of the duration of the antenna switching interval (I1).

11. The method as described in any one of claims 1 to 2, Its features are, The radio transceiver (TR) is a Bluetooth radio transceiver.

12. The method as described in any one of claims 1 to 2, Its features are, The radio transceiver (TR) is part of a motor vehicle (1) or a mobile terminal (2).

13. The method as described in claim 10, Its features are, During the scanning interval (I2), the Bluetooth radio transceiver performs a scan in the "Initiate / Scan" operating state.

14. The method as described in claim 11, Its features are, The radio transceiver (TR) is a Bluetooth Low Energy radio transceiver.

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