DE102007012847A1 - Navigation, location, positioning, localization and communication based on IDMA - Google Patents

Abstract

A method for the joint transmission of communication data of a communication device and data for determining the position of the communication device, characterized by the steps of encoding in each case an uncoded position input signal (Nav.1, Nav. 2) and a communication input signal (Kom.1, Kom.2, Kom. 3) by means of Forward Error Correction (106), scrambling (107) the coded bit sequence respectively obtained from the Forward Error Correction, mapping the scrambled Bi9, 110), linearly adding (111) the processed position input signal and the processed communication input signal by means of Interleave Division Multiplexing and Output (112) of the added signal.

Description

The The invention relates to a method for joint transmission of communication data of a communication device and of Data for determining the position of the communication device.

today Navigation, location, positioning and localization systems are mostly based on a measurement of runtime differences, which are common be supported by other measuring principles, such. B. inertial systems. Used to measure runtime differences you have several transmitters of known position and a receiver, whose position should be determined as accurately as possible. at satellite-based navigation systems correspond to the Transmit the satellite while the receiver is portable is. The same applies to most terrestrial Navigation systems. For the position determination of a point in a spatial coordinate system, at least four metrologically simultaneously visible transmitter needed.

A from obvious prior use known alternative solution offers the localization system of the company "Cairos technologies AG. "In this system, the position of a portable transmitter calculated while the receivers are stationary. To determine the location coordinates, four will be used simultaneously visible receiver needed with known position. By this method could z. B. the barrel of a ball, by having a transmitter located across the playing field when four receivers are placed at the edge of the field become.

Around the transmission signals - with "Cairos" the received signals - from each other to be able to separate, one uses according to the prior art so-called access procedures. The GPS and GALILEO access method are based on a special code division technique called direct-sequence Code Division Multiple Access (DS-CDMA) is called while the GLONASS is based on a frequency division multiplexing technique (FDMA). Also access methods using Time Division Multiplexing (TDMA) work, for example, in the IEEE 802.15.3 PAN standard application.

Even though in the course of the development of the GALILEO process intensive technical Discussions about the benefits and the need for a Reverse channels currently take place satellite-based and terrestrial navigation systems no return or Hinkanal to the calculated positions to the transmitter or receiver to convey. Such a function would have z. B. in emergency calls considerable advantages. The recall channel One realizes today with the help of satellite-supported or terrestrial mobile radio systems, such. GMS. UMTS, Iridium u. a.

The prior art can thus be stated that: navigation, location, positioning, localization are currently performed separately from the communication. This document, for example, the publications US 2006/0039271 . CA 2 504 713 A1 and DE 41 93 230 C1 ,

task Therefore, the invention is a method for common navigation, Location, positioning, localization and communication. The procedure should be flexibly configurable against interference very robust, regarding the DS-CDMA system for the possibility complete a terrestrial complement of GPS and GALILEO be compatible and optionally an encryption of the data streams exhibit.

The method according to the invention is based on the use of the Interleave Division Multiple Access Access Method (IDMA) for the purpose of navigation, location, positioning and localization and will be explained in the following description. This access method has hitherto only been discussed and described in connection with communication systems, but not with positioning systems ( P. Frenger, P. Orten, T. Ottosson: Code-spread CDMA using maximum free distance low rate convolutional codes, IEEE Trans. Commun., Vol. 48, no. 1, pp. 135-144, Jan. 2000 ; L. Ping: Interleave division multiple access and chip-by-chip iterative multi-user detection, IEEE Commun. Magazine, vol. 43, no. 6, pp. 19-23, June 2005 ).

IDMA is a special CDMA access method. Each data stream, the represent a positioning or a data signal is initially coded to give it redundancy Purposes of error correction is added (Forward Error Correction, FEC). In the simplest case, the data is duplicated repeated. For each data stream, the same encoder used, but not mandatory. After the coding is a binary data stream - as a bit sequence - before, the due to existing redundant shares an error detection and / or error correction makes possible, causing the system robust against disturbances of all kinds becomes.

Subsequently For example, the order of coded bits becomes deterministic or pseudo-stochastic scrambled by a so-called. Interleaver (INT), where for each data stream uses a different interleaver. The used Interleaver thus has two functionalities: it allows a separation of the data streams and he allows a data encryption. Receiver side is the original order of encoded data reconstructed the associated deinterleaver, so that only authorized users can use the information.

in the Further, the scrambled bits become scrambling undergoing deterministic or pseudo-stochastic negation to make the data stream averaging. Again, you can the same scrambler (SCR) is used for each data stream which is again not mandatory. The scrambled and optionally scrambled bits are generated by a Mapper (MAP) imaged on the complex signal space, taking one in the simplest Embodiment a "0" to a "+1" and convert a "+1" to a "-1". Also conceivable are higher modulation z. PSK, ASK or QAM.

Before sending, optionally several data streams can be added linearly by means of interleave division multiplexing. In known communication systems, this method is often used to vary the data rate ( H. Schöneich, PA Higher: "Adaptive Interleave Division Multiple Access - A Potential Air Interference for 4G Bearer Service and Wireless LANs" Proc. Is Int. Conf. On Wireless and Optical Communications and Networks (WOCN 2004), Muscat, Oman. Pp. 179-182, June 2004 ). It is also possible to transmit a plurality of communication signals and navigation signals simultaneously, optionally each with a variable data rate, wherein the second inventive step exists. With conventional navigation systems, there is only the possibility of superimposing two data streams due to a modulo-2 addition.

The Simultaneous transmission of multiple communication and Navigation signals - optionally each with variable data rate - is explained below with reference to the accompanying drawings. Showing:

1 a particularly preferred signal flow diagram of a transmission system for two navigation and three communication signals,

2 a representation of the bit error rate with uniform power allocation for coded and uncoded IDMA and

3 a representation of the bit error rate at non-uniform power allocation for coded and uncoded IDMA.

• – FEC_i: Forward Error Correction des i-ten Datenstroms,
• – INT_i: Interleaver des i-ten Datenstroms,
• – SCR_i: Scrambler des i-ten Datenstroms,
• – MAP_i: Mapper des i-ten Datenstroms,
• – a_i: Amplitude des i-ten Datenstroms,
• – φ_i: Phase des i-ten Datenstroms,
• – 101–105 Datensignale,
• – 106 Forward Error Correction,
• – 107 Interleaver,
• – 108 Scrambler,
• – 109 Mapper,
• – 110 komplexer Signalraum,
• – 111 Multiplexer

The abbreviations used here mean:

• FEC _i : forward error correction of the i-th data stream,
• INT _i : interleaver of the ith data stream,
• SCR _i : scrambler of the ith data stream,
• MAP _i : mapper of the ith data stream,
• A _i : amplitude of the ith data stream,
• - φ _i : phase of the ith data stream,
• - 101 - 105 Data signals
• - 106 Forward Error Correction,
• - 107 interleaver
• - 108 scrambler,
• - 109 Mapper
• - 110 complex signal space,
• - 111 multiplexer

In the 1 There is an uncoded data stream of 4 bits, which may be communication signals or navigation signals. By using a four-time repetition code, one obtains sixteen coded bits. The order of these 16 bits is pseudorandomly scrambled by a sixteen-length interleaver. The scrambler inverts every other bit, which causes the data stream to be averaged, regardless of the uncoded bit sequence used at the beginning. The mapper generates a bipolar symbol sequence which can be used as a data block, transmission signal or the like.

For a partial secrecy, not all interleaver patterns used published what the possibilities, already in addition to encode before encoding, but does not exclude.

• – Mehrere binäre Datensätze d_u,m, die im Folgenden als Schicht bezeichnet sind, werden einem Benutzer u zugewiesen.
• – Jeder binäre Datensatz (Schicht) d_u,m des Benutzers u, 1 ≤ u ≤ U, 1 ≤ m ≤ M, wird von einem niederratigen Kanalcodierer (ENC) codiert, der in der Regel für alle Benutzer u und Schichten m identisch ist, wobei verschiedene Codierer angewandt werden können.
• – Nach der Codierung sollte jedoch, wie bereits beschrieben, eine Verwürfelung durchgeführt werden, bei der die codierten und verwürfelten Zeichen von einem Chip-für-Chip-Interleaver π_u,m verschachtelt werden.
• – von der Konzeption her ist jeder Schicht ein anderer Chip-für-Chip-Interleaver π_u,m zugeordnet; alternativ können sich auch mehrere Schichten eines Benutzers den gleichen Interleaver teilen.
• – Die Schichten können über eine oder mehrere Sendeantennen pro Benutzer verteilt sein, wobei M Sendeantennen der Extremfall sind.
• – Die verschachtelten Chips werden vor der Übertragung linear überlagert. Herkömmlicherweise wird jeder Schicht, die einer bestimmten Sendeantenne entspricht, eine eindeutige Phase und eine eindeutige Amplitude zugewiesen. Durch den Einsatz gleichförmig verteilter Phasen wird der zweidimensionale Signalraum für jede Sendeantenne vollständig ausgenutzt. Der Einsatz verschiedener Amplituden – d. h. durch ungleichmäßige Leistungszuteilung – kann die Bitlast signifikant verbessern und Schicht für Schicht ein ungleicher Fehlerschutz (UEP) realisiert werden.
• – Die Datenrate wird geändert, indem, anstatt das Modulationsalphabet oder der Kanalcode geändert werden, die Anzahl überlagerter Schichten pro Benutzer angepasst wird („adaptive Bitbelastung"), obgleich auch Modulationsalphabet und Kanalcode geändert werden können. Der Hauptvorteil binärer Datenströme ist die real bewertete Verarbeitung auf der Empfängerseite. Binäre Datenströme sind gegenüber linearer und nicht-linearer Störung, Phasenjitter, schnellem Fading usw. weniger anfällig. 4-QAM ist lediglich ein Spezialfall mit zwei orthogonalen Schichten pro Antenne.

In the following, the method according to the invention, which can also be referred to as multi-layer IDMA - but should not be confused with a multi-layer turbo space-time code, will be explained in greater detail on the basis of a particularly preferred embodiment. In detail, the multi-layer IDMA method according to the invention comprises:

• - Several binary data sets d _{u, m} , which are referred to below as layer, are assigned to a user u.
• - Each binary record (layer) d _{u, m of} the user u, 1 ≤ u ≤ U, 1 ≤ m ≤ M, is encoded by a low-rate channel encoder (ENC), which is usually identical for all users u and layers m where different coders can be used.
• However, after the encoding, as already described, scrambling should be performed in which the coded and scrambled characters are interleaved by a chip-by-chip interleaver π _{u, m} .
• - conceptually, each layer is assigned a different chip-by-chip interleaver π _{u, m} ; Alternatively, multiple layers of a user may share the same interleaver.
• The layers may be distributed over one or more transmit antennas per user, with M transmit antennas being the extreme case.
• The interleaved chips are superimposed linearly before transmission. Conventionally, each layer corresponding to a particular transmit antenna is assigned a unique phase and a unique amplitude. By using uniformly distributed phases, the two-dimensional signal space is completely utilized for each transmitting antenna. The use of different amplitudes - ie due to uneven power allocation - can significantly improve the bit load and realize layer by layer unequal error protection (UEP).
• The data rate is changed by adjusting the number of superimposed layers per user ("adaptive bit loading") instead of modifying the modulation alphabet or the channel code, although modulation alphabet and channel code can be changed The main advantage of binary data streams is the real-valued processing Binary data streams are less susceptible to linear and non-linear noise, phase jitter, fast fading, etc. 4-QAM is only a special case with two orthogonal layers per antenna.

at In a single user scenario, multi-layer IDMA has been used as interleave division multiplexing (IDM), or superposition coding called. Any means to Peak-to-average power reduction (such as precoding, selective Mapping, Clipping, Filtering, etc.) can be executed additionally become. It is known that superposition coding opposite Clipping is robust. Based on receiver-side reliability information, which are available in iterative receivers anyway can stand, the number of layers per user and / or the transmission power can be adjusted.

wobei k der Chipindex, a_u,m ∊ IR₊ die Amplitude der m-ten Schicht von Benutzer u, φ_u,m ∊ [+ π/2, –π/2] die Phase der m-ten Schicht von Benutzer u ist, und x_u,m [k] ∊ {+1, –1} die verschachtelten Chips sind. Die M Phasen sind bevorzugt gleichförmig verteilt, um den Zeichenraum zu füllen, wohingegen die M Amplituden bezüglich Bitbelastung, Empfängerleistung und UEP optimiert werden können.For the sake of expediency, as a possible realization, a one-antenna system is assumed below. A generalization to several antennas is then easy to make. Suppose each layer is assigned a unique phase and amplitude according to a particular transmit antenna. The superimposed chips of user u, 1 ≤ u ≤ U, can then be written as

where k is the chip index, a _{u, m} ∈ IR _{+ is} the amplitude of the m th layer of user u, φ _u , mε [+ π / 2, -π / 2] is the phase of the m th layer of user u , and x _{u, m} [k] ε {+1, -1} are the interleaved chips. The M phases are preferably uniformly distributed to fill the character space, whereas the M amplitudes can be optimized for bit loading, receiver power and UEP.

wobei g_Tx(t) der Basisbandimpuls und T_c die Chipdauer sind. Bei Annahme eines linearen Kanals wird das äquivalente Chipraten-diskrete-Zeit-Modell erhalten als

wobei L die effektive Speicherlänge und n[k] der k-te Rauschabtastwert sind. Die Kanalkoeffizienten h_u,l[k] umfassen Impulsformung, physikalischen Kanal, Empfangsfilterung und Abtastung. Ein Empfänger vom Rake-Typ kann verwendet werden, um von der ISI (Intersymbol Interference-Nachbarzeichenstörung) zu profitieren.On the uplink, the transmit signal can be written in complex baseband notation as

where g _Tx (t) is the baseband pulse and T _{c is} the chip duration. Assuming a linear channel, the equivalent chip rate discrete time model is obtained as

where L is the effective memory length and n [k] is the kth noise sample. The channel coefficients h _{u, l} [k] include pulse shaping, physical channel, reception filtering and sampling. A rake-type receiver can be used to benefit from the ISI (Intersymbol Interference Neighbor Signal Disturbance).

• – Datenquelle: M voneinander unabhängige Zufallsdatenströme mit jeweils einer Länge 320 sind erzeugt worden.
• – Codierer: Es wurden zwei Fälle untersucht: 1) Eine Wiederholungscodierer der Länge 8 wurde ohne FEC-Codierung angewendet. Dies wird als „uncodierter IDMA" bezeichnet. 2) Ein rekursiver systematischer 4-Zustandsraten-1/2-Faltungscodierer wurde in Verbindung mit einem nachfolgenden Wierholungscodierer der Länge 4 angewendet. Dies wird als „codierter IDMA" bezeichnet. Zwei Informationsbits werden durch bekannte Flankenformungsbits substituiert. Der entsprechende Ratenverlust kann durch Puncturing oder Tail-Biting vermieden werden. Die Codierung erfolgt hier Schicht für Schicht, doch kann die Leistung durch Codierung über die Schichten hinweg verbessert werden.
• – Verwürfler: Jedes zweite Codezeichen wird umgeschaltet.
• – Interleaver: Ein Satz aus M pseudozufälligen, voneinander unabhängigen Interleavern der Länge 2560 (= 320·8) sind erzeugt worden. Es erfolgte kein Aufwand in Richtung Optimierung des Interleaver. Es sei angemerkt, dass die Konvergenz durch als „Stapeln" [stacking] bekanntes Verschachteln über die Schichten hinweg verbessert werden kann.
• – Kanalmodell: Eine synchrone Übertragung über einen komplexwertigen AWGN-Kanal wurde durchgeführt. Es wurden Simulationsergebnisse für eine gleichförmige bzw. ungleichförmige Leistungszuteilung erhalten. Im Fall einer ungleichförmigen Leistungszuteilung wurde von zwei Amplitudenpegeln a_u,m [k] ∊ {α1, α2} (die zu zwei Empfindlichkeitsklassen gehören) ausgegangen. Wenn beide Empfindlichkeitsklassen von gleicher Größe sind, kann die Bitfehlerrate (BER) nach unten begrenzt werden als
  
  wobei α₁ = 10^–ρ/20 und
  
  α₁ ≤ α₂. Der nicht-negative Parameter ρ ist der asymptotische Verlust in dB bezüglich einer binären antipodalen Zeichengebung, wenn Konvergenz erreicht wird. Im Spezialfall einer gleichförmigen Leistungszuteilung ist ρ = 0 dB. (Es sei zu erwähnen, dass bei optimierter Leistungssteuerung die Leistung weiter verbessert werden könnte).
• – Multischicht-Detektor: Es wurde ein aus der Literatur vorgeschlagene iterative Multibenutzer-/Multischicht-Detektor angewendet. Nach Detektion werden Verschachtelung und Verwürfelung umgekehrt,
• – Decodierer: Ein Max-Log-APP-Decodierer wurde zum Decodieren des FEC-Codes verwendet. Er gibt sowohl über die (für die Endentscheidung verwendeten) Informationsbits als auch über die (für die iterative Verarbeitung verwendeten) Codebits weiche Entscheidungen.
• – Iterationen: Log-Wahrscheinlichkeitswerte (oder zumindest gute Approximationen davon) werden von Stufe zu Stufe ausgetauscht. 20 Iterationen wurden durchgeführt, wenn auch in vielen Situationen eine Konvergenz viel früher erreicht wird,
• – Kanalabschätzung: Am Empfänger werden perfekte Kanalzustandsinformationen angenommen.

The numerical results presented here are based on the experimental setup described below as a practicable solution for the invention:

• Data source: M independent random data streams, each having a length 320, have been generated.
• - Encoder: Two cases were investigated: 1) A length 8 repetitive coder was used without FEC coding. This is referred to as an "uncoded IDMA." 2) A recursive 4-state rate 1/2-convolutional systematic coding coder was used in conjunction with a subsequent 4-length lengthwise coder, referred to as "coded IDMA." Two information bits are substituted by known edge shaping bits. The corresponding rate loss can be avoided by puncturing or tail-biting. Coding is done layer by layer, but performance can be improved by coding across layers.
• - Scrambler: Every second code character is switched.
• Interleaver: A set of M pseudo-random, independent interleavers of length 2560 (= 320 x 8) have been generated. There was no effort towards optimizing the interleaver. It should be noted that convergence can be improved by interlayer nesting known as "stacking".
• - Channel Model: A synchronous transmission over a complex-valued AWGN channel has been performed. Simulation results for a uniform power allocation were obtained. In the case of a non-uniform power allocation, two amplitude levels a _{u, m} [k] ε {α1, α2} (belonging to two sensitivity classes) were assumed. If both sensitivity classes are the same size, the bit error rate (BER) can be limited to lower than
  
  where α ₁ = 10 ^{-ρ / 20} and
  
  α ₁ ≤ α ₂ . The non-negative parameter ρ is the asymptotic loss in dB with respect to binary antipodal signaling when convergence is achieved. In the special case of a uniform power allocation, ρ = 0 dB. (It should be noted that with optimized power control performance could be further improved).
• Multilayer Detector: A multi-user / multi-layer iterative detector proposed in the literature was used. After detection, nesting and scrambling are reversed,
• Decoder: A Max Log APP decoder was used to decode the FEC code. It gives soft decisions both on the information bits (used for the final decision) and on the code bits (used for the iterative processing).
• Iterations: Log likelihood values (or at least good approximations thereof) are exchanged from level to level. Twenty iterations have been performed, although in many situations convergence is achieved much earlier,
• - Channel estimation: Perfect channel state information is accepted at the receiver.

In 2 For example, the BER is plotted over E _b / N ₀ for uncoded IDMA (solid line) and coded IDMA (dashed line) for uniform power allocation. In the uncoded case, the one-user boundary is reached for about M = 24 users (or layers), whereas in the coded case it is achieved for about M = 16 users (or layers) in the signal-to-noise ratio (SNR) of interest. This corresponds to a bandwidth efficiency of 3 bit / s / Hz or 2 bit / s / Hz. It should be noted that more layers can be supported if longer interleavers are used, for example by stacking. Nevertheless, uniform power allocation is the worst case in terms of bandwidth efficiency.

In 3 the BER is plotted on non-uniform power allocation over E _b / N ₀ for uncoded IDMA and for coded IDMA, assuming two sensitivity classes of equal size. The parameter ρ (4 dB, 5 dB and 6 dB) gives the asymptotic loss with respect to the antipodal character in dB when convergence is achieved. Corresponding lower limits are shown in dashed lines. With two sensitivity classes, bandwidth efficiency can be doubled in bounds at the cost of power loss. With an asymptotic loss of 6 dB, about M = 48 users (or layers) can be supported if longer interleavers are used, for example by stacking. This corresponds to a bandwidth efficiency of 6 bit / s / Hz.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• US 2006/0039271 [0006]
• - CA 2504713 A1 [0006]
• - DE 4193230 C1 [0006]

Cited non-patent literature

• P. Frenger, P. Orten, T. Ottosson: Code-spread CDMA using maximum free distance low rate convolutional codes, IEEE Trans. Commun., Vol. 48, no. 1, pp. 135-144, Jan. 2000 [0008]
• - L. Ping: Interleave division multiple access and chip-by-chip iterative multi-user detection, IEEE Commun. Magazine, vol. 43, no. 6, pp. 19-23, June 2005 [0008]
• - H. Schöneich, PA Higher: "Adaptive Interleave Division Multiple Access - A Potential Air Interference for 4G Bearer Service and Wireless LANs" Proc. Is Int. Conf. On Wireless and Optical Communications and Networks (WOCN 2004), Muscat, Oman Pp. 179-182, June 2004 [0012]

Claims (7)

A method for the joint transmission of communication data of a communication device and data for determining the position of the communication device, characterized by the steps of - coding in each case an uncoded position input signal (Nav. 1, Nav. 2) and a communication input signal (Kom. 1, Kom. 2, Com ) by means of Forward Error Correction ( 106 ), - scrambling ( 107 ) of the coded bit sequence respectively obtained from the forward error correction, - mapping of the scrambled bits of the bit sequence to a complex signal space ( 109 . 110 ), - linear adding ( 111 ) of the processed position input signal and the processed communication input signal by means of interleave division multiplexing and output ( 112 ) of the added signal. A method according to claim 1, characterized in that the scrambled bits of the bit sequence before mapping to a complex signal space ( 109 . 110 ) are scrambled independently of the coded bit sequence of the input signals (Nav. 1, Nav. 2, Com. 1, Com. 2, Com. 3). Method according to one of the preceding claims, characterized in that the order of coded bits scrambled pseudo-stochastically. Method according to one of the preceding claims, that the coded position input signal and the coded communication input signal be scrambled identically. Method according to one of claims 2 to 4, characterized in that the data of the position input signal scrambled differently from the data of the communication input signal become. Transmitter, characterized in that the transmitter for Implementation of the method according to one of the claims 1 to 5 is set up. Receiver, characterized in that the receiver to receive and decrypt a according to the method of claims 1 to 5 coded Signal is set up.